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Good News: 243 Papers from the 'Journal of Soil and Water Conservation' Included in CNKI's High-Impact Paper List

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Effects of Soil Erosion on Soil Quality in Slope Farmland of Typical Thick-layer Mollisol Region of Northeast China

Liang Rui, Zheng Fenli

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[Subjective] Elucidating the effects of soil erosion-deposition on the soil quality of slope farmland in Mollisol region of Northeast China is crucial for protecting black soil resource and maintaining its sustainable utilization. [Methods] This paper, selecting two sloping farmlands located at Keshan county, Heilongjiang province as the study site, utilized the ¹³⁷Cs tracer technique to estimate soil erosion rates and the minimum data set (MDS) method to calculate soil quality index (SQI) to analyze impacts erosion-deposition of sloping farmland on soil quality in typical thick-layer mollic regions. [Results] 1) The soil erosion-deposition rate of slope farmland in the study area ranges from -1563.2 to 7916.1 t/km2^/a, with an average erosion rate of 2669.0 t/km2^/a. The spatial distribution of soil erosion rate along the hillslopes was characterized by intensive erosion in the middle and lower slope segment, light-moderate erosion in the top and upper slope segment, deposition at the 50 m slope segment at the foot of the slope, and the most severe slope segment of soil erosion was distributed in 120-170 m slope length. 2) The soil quality evaluation indicators based on the MDS included soil clay, soil organic carbon (SOC), total phosphorus (TP), available nitrogen (AN), soil microbial biomass carbon (MBC) and β-1,4-glucosidase (BG). Moreover, there was a significant linear positive relationship between the MDS-SQI and SQI based on the full data set (p < 0.001), indicating that the MDS could replace the full data set and really reflected the soil quality regime of the slope farmland in the study area. 3) In the study area, there was a significantly negative correlation between SQI and soil erosion rates in the erosion sites (p < 0.01); while the SQI numerally increased with deposition rates without significant difference in the depositional sites. The SQI in the erosion sites reduced by 13.3% on average compared with that in the deposition sites; and the spatial distribution of the SQI along hillslopes was opposite to that of the soil erosion rates. [Conclusion] Soil erosion in the study area is the key driving force to soil quality degradation in sloping farmland.
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Influence and Mechanisms of Vegetation Restoration Patterns on Soil Saturated Hydraulic Conductivity in Gully Catchments of the Loess Plateau

XU Yin, FU Suhua

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[Objective] Soil saturated hydraulic conductivity (Ks) serves as a critical parameter characterizing the transport of water and solutes in soil, playing a vital role in understanding and predicting soil moisture movement and erosion processes. Studying the variation characteristics and driving factors of Ks across various vegetation restoration models in gully watershed regions of the Loess Plateau is essential for advancing regional soil erosion mitigation efforts. [Methods] Thirty-eight typical vegetation restoration plots ( 5 bare land, 3 dry land, 8 arbor forest land, 3 other forest land, 5 shrub forest land and 14 other grassland ) in Zhifanggou small watershed were selected as the research objects. The Ks, soil physical and chemical properties and root characteristics of 0-10 cm soil layer in different plots were measured. Spearman correlation analysis, partial least squares regression ( PLSR ) and multiple stepwise regression analysis were used to reveal the influence mechanism of vegetation restoration mode on Ks, and the Ks prediction model was established.[Results] Significant differences in saturated hydraulic conductivity (Ks) were observed across vegetation restoration patterns (P<0.05). The mean Ks values followed the order: shrub forest land (1.46 mm/min) > other forest land (1.36 mm/min) > other grassland (1.23 mm/min) > arbor forest land (1.04 mm/min) > dry land (0.65 mm/min) > bare land (0.15 mm/min). Spearman analysis and PLSR revealed that sand fraction, clay content, bulk density, maximum water retention, non-capillary porosity, root volumetric density, root mass density, and root mass densities in 1-2 mm and 0-1 mm diameter classes were critical determinants of Ks. Stepwise regression showed substantial improvement in model explanatory capacity upon integrating root parameters. The integrated model highlighted that intermediate roots optimized Ks through pore network expansion and compaction effect mitigation. [Conclusion] Vegetation restoration markedly elevates Ks via root-mediated soil structural modifications, particularly through pore architecture optimization. The results offer a scientific foundation for refining ecological restoration strategies and enhancing hydrological model parameterization in Loess Plateau ecosystems.
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Impact of land use change and soil type on SOC in Northeast China, 1990-2020

Zhuyuan Qing

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[Objective]Land use change is an important driving factor affecting soil carbon storage changes. In order to further explore the impact of land use and cover change (LUCC) on carbon storage of specific soil types in Northeast China. [Methods]this study used land cover data to analyze the relationship between land use change and soil types in Northeast China from 1990 to 2020, and to explore its impact mechanism on soil organic carbon (SOC) sequestration. [Results]The results showed that: (1) land use change is dominated by the decrease in the area of cropland and wetland, and the increase in the area of forest and grassland (1535-4213 km2). (2) The decrease in cropland area was mainly converted into grassland (64%), other land (29%) and forest (6%). Among them, meadow soil, dark brown soil and chernozem soil were the main soil types. The areas with reduced wetlands were mainly distributed in black soil and meadow soil areas. When other land use types were converted into forest land and grassland, the main soil types involved were dark brown soil (15%-41%) and meadow soil. (3) In the past 30 years, the study area was generally in a carbon source state, and the total SOC decreased by 0.046 Pg. Specifically, the SOC storage of grassland and forest increased by 0.102 Pg and 0.283 Pg, respectively, while the SOC storage of cropland and wetland decreased by 0.111 Pg and 0.007 Pg, respectively, and the SOC storage of other land use types decreased by 0.313 Pg. (4) Long-term cultivation (main soil types: meadow soil, Aeolian sandy soil and Albic soil) caused a loss of 0.341 Pg in SOC storage; the reclamation of natural land (woodland and grassland) caused a loss of 5.79% and 4.32% in SOC, respectively. [Conclusion]In summary, the negative SOC storage in Northeast China is mainly caused by extensive land type conversion and long-term cultivation. In the future, we should focus on the restoration of long-term cultivated land (mainly meadow soil) and the protection of natural land.
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Response of Slope Erosion Processes and Hydrodynamic Indicators to Inflow Patterns on Spoil Heaps

Chen Yueyan, Niu Yaobin

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Abstract：[Objective] Spoil heaps, a major source of soil erosion in construction projects, feature a platform-slope structure, where platform runoff induces severe slope erosion in different inflow patterns. However, the response mechanisms of the slope erosion process to the inflow patterns remain unclear. [Methods] Artificially simulated scouring experiments were conducted with two inflow patterns (concentrated-flow and surfaced-flow) and three flow rates (4, 8 and 12 L/min), to reveal the effects of different inflow patterns on the sediment production and hydrodynamic characteristics of slope erosion. [Results] 1) The process of sediment and runoff production were the similar under both concentrated-flow and surfaced-flow. The process of runoff production exhibited a transition from jumping to stabilization, while the process of sediment production showed a rapid decrease and then a fluctuating reduction. Compared with the surfaced-flow, the soil erosion rate showed stronger volatility in concentrated-flow, with the coefficient of variation of 71.49%~111.94%. 2) Mean flow velocity in concentrated-flow was significantly increased 28.15%~52.85% compared with surfaced-flow (p< 0.05), with increasing in flow rate. 3) Runoff conditions under both concentrated-flow and surfaced-flow were transitional flow and turbulent flow, while there was a significant difference in runoff state, which was rapid flow in concentrated-flow and tranquil flow in the surfaced-flow. 4) Soil erosion rate was positively correlated with the Reynolds number, resistance coefficient, shear stress, runoff power, and runoff unit energy under the two inflow patterns (p< 0.01). However, the optimal hydrodynamic indicators differed, with runoff power (R2= 0.68) for surfaced-flow and runoff shear (R2= 0.80) for concentrated-flow. 5) Compared with surfaced-flow, soil erodibility indexes Kτ, Kω and Kε in concentrated-flow increased by 166.67%, 81.25% and 113.86%, respectively, and the corresponding critical hydrodynamic thresholds (τ0, ω0, ε0) increased by 19.78%, 40.70%, and 42.11%, respectively. [Conclusion] The concentrated-flow shows stronger turbulence, has higher erosion energy, and triggers serious soil erosion. This study reveals the influence mechanism of inflow patterns on the slope erosion process and provides an important theoretical basis for the development of slope erosion prediction models under different inflow patterns for spoil heaps.
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Construction of ecological security pattern in Anhui province from the perspective of ecosystem service supply and demand

Hanyuexia, Dong Bin

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[Objective]Driven by global climate change and the continuous intensification of human social and economic activities, we explored the imbalance between supply and demand of ecosystem services in Anhui Province, and provided reliable basis for regional ecological security construction.[Methods]Anhui Province was selected as the research area, and the InVEST model and hotspot analysis method were integrated to systematically evaluate the supply and demand capacity of the four key services of water yield, habitat quality, carbon storage and soil conservation and the comprehensive cold hotspot distribution pattern in Anhui province from 2003 to 2023. From the perspective of ecosystem service supply and demand, we constructed the ecological supply and demand pattern of Anhui province with the help of circuit theory[Reults]1) From 2003 to 2023, water yield would first decrease and then increase, with a spatial distribution of "more in the south and less in the north". Carbon storage showed a decreasing trend. The habitat quality was higher in the south than in the north and decreased year by year. The amount of soil retention decreased first and then increased, with an overall upward trend.2) From 2003 to 2023, the demand for water production service, carbon sequestration service and habitat demand would generally show an upward trend. The overall demand for soil conservation services (soil erosion) in Anhui province showed a significant downward trend.3) The hotspots of comprehensive ecosystem services supply in Anhui Province were characterized by "high in the south and southwest, and low in the north". The hot spots of comprehensive demand were high in the northwest and low in the southeast. The comprehensive supply-demand ratio showed the characteristics of "high in the south and low in the north".4) The research consensus included 40 supply sources and 36 demand sources; There were 93 supply corridors and 96 demand corridors. Forming an ecological supply and demand pattern of "southern screen and northern link, river basin through".[Conclusion]From the perspective of supply and demand relationship, we constructed a multi-objective coordinated ecological supply and demand network, provided scientific basis for the optimal allocation of regional resources and sustainable ecosystem management, and formed a decision-making support system with both theoretical value and practical guidance.
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Runoff Prediction and Influencing Mechanism in the Erhai River Basin Coupled with Climate and Land Use Change

xufan, linyilin

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[Objective] The study aims to explore the impact of future climate and land use changes on runoff prediction and its influencing mechanisms in lake basins, which helps to understand hydrological response patterns, optimize water resource allocation, and formulate adaptive management strategies. [Methods] Taking the Erhai Lake Basin as the study area, the research integrates CMIP6 climate data and land use data, coupling the PLUS model and SWAT model to construct a framework for predicting runoff under future climate and land use change scenarios. This framework predicts runoff in the Erhai Lake Basin based on three climate scenarios (SSP1-1.9, SSP2-4.5, and SSP5-8.5) under different Shared Socioeconomic Pathways (SSPs) and future land use change scenarios. The optimal parameter geographical detector is used to reveal the main driving factors and their interactions affecting runoff in the Erhai Lake Basin. [Results] 1) Cultivated land, forest land, and grassland are the dominant land use types in the Erhai Lake Basin over the long term. From 2010 to 2020, urbanization drove the expansion of construction land, encroaching on cultivated land and forest land. By 2030, construction land is expected to reach 18396 hm2, with an additional 1427 hm2 of new construction land, mainly converted from cultivated land, reflecting pressures from population growth and infrastructure demands. 2) The runoff in the Erhai Lake Basin in 2030 shows certain variations under the three scenarios. The highest runoff is observed under the SSP5-8.5 scenario (19.592 m3/s), followed by the SSP1-1.9 scenario (18.013 m3/s), and the lowest under the SSP2-4.5 scenario (17.387 m3/s). Despite variations under different emission scenarios, the overall trend remains relatively stable. 3) The geographical detector results indicate that wind speed exhibits strong independent explanatory power in most years, while the combination of precipitation and other factors shows highly significant interactive explanatory power across all years. [Conclusion] The runoff in the Erhai Lake Basin in 2030 remains relatively stable across different scenarios, with the annual average runoff following the trend of SSP5-8.5 > SSP1-1.9 > SSP2-4.5. Wind speed has the greatest impact on runoff under all three scenarios in 2030, while the combination of precipitation and other factors outperforms other combinations in influencing runoff.
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Effects of Profile Structure and Hydrologic Conditions on Runoff Process and Sand Loss at Coral Sand Slopes

Wang Linhua, Yan Junhua

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[Objectives] Compared to natural-formed tropical coral islands, newly-constructed coral islands exhibit distinct compactied clay layers due to the hydraulic filling and deposition during formation processes. To explore the hydraulic properties and hydrological conditions effects on rainfall infiltration, subsurface flow and coral sand transport. [Methods] This study focuses on the clay compaction layer in coral sand profiles. Through in-situ field investigations and sampling, we characterized the textural type and hydro-physical properties of coral sand at different depth. Laboratory rainfall simulation experiments were conducted to investigate hydrological responses and sand transport processes under varying profile compositions, comparing homogeneous slopes with those containing clay compaction layers. [Results] These results showed that coarse coral sand has a high hydraulic conductivity, whereas the clay compaction layer exhibits extremely low permeability. The saturated hydraulic conductivity of clay compaction layer was only 8% of the other coarse coral sand. The homogeneous slopes allowed complete rainwater infiltration without surface runoff generation, while clay compaction layers redirect 87% of rainfall as subsurface flow, triggering coral sand particle loss. Hydrological condition shifts from free drainage to saturated and seepage flows amplify the rates and total amount of subsurface runoff and sand transport, though the compaction layer with low-permeability may mitigates coral sand loss under seepage condition. [Conclusion] The clay compaction layer can significantly alter hydrological processes and sand transport, leading to shallow hydrological processes and the development of dissolution fissures. These findings have critical implications for improving our understanding of freshwater cycling processes and guiding eco-friendly engineering practices in coral islands.
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Aggregate Distribution Characteristics of Granitic Sandy Soil and Eel Clayey Soil and Their Effects on Cadmium Adsorption and Speciation

HE Ru-jing, LONG Jian

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[Objective] To elucidate the influence mechanisms of the physicochemical properties of soil aggregates with different particle sizes on cadmium (Cd) speciation, this study investigated the distribution characteristics of aggregates in typical paddy soils and the effects of different aggregate size fractions on Cd environmental behavior. [Methods] Two Cd-contaminated paddy soils were selected, including granitic sandy soil (developed from granite) and eel clayey soil (developed from shale and slate). Soil aggregates were separated into four size fractions using the wet-sieving method: macroaggregates (2–8 mm), intermediate aggregates (0.25–2 mm), microaggregates (0.053–0.25 mm), and silt-clay particles (<0.053 mm). The adsorption effects of different-sized aggregates on Cd were analyzed after removing organic matter and free iron oxides. [Results] Both soils were dominated by macroaggregates. The aggregate structure of the eel clayey soil was more stable than that of the granitic sandy soil, with higher mean weight diameter (MWD) and geometric mean diameter (GMD). The granitic sandy soil had a higher proportion of fine aggregates, with looser structure and lower stability, mainly due to the lower contents of organic matter and free iron oxides in its parent material. As aggregate size decreased, the contents of organic matter, free iron oxides, and cation exchange capacity (CEC) significantly increased. Cd adsorption capacity progressively enhanced with reduced aggregate size, reaching maximum adsorption in silt-clay particles. The removal of organic matter significantly reduced the Cd adsorption capacity, whereas the removal of free iron oxides had a relatively smaller effect. [Conclusion] The compositional and structural stability differences in aggregates from distinct soil types significantly affect Cd adsorption and speciation patterns. These findings provide scientific basis for deciphering the evolution of heavy metal pollution in paddy fields and formulating remediation strategies.
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Changes in Climate Elements over China under Different Warming Scenarios Based on NEX-GDDP-CMIP6 datasets

wenshanshan

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[Objective] Against the backdrop of persistent global warming impacts on climate systems, this study investigates the evolving trends and spatial patterns of climatic elements across China under different warming scenarios, aiming to provide a scientific foundation for formulating differentiated climate adaptation strategies. [Methods] Using NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) CMIP6 high-resolution data, this study evaluates the changes in climate elements across China under global warming scenarios of 1.5?°C to 5?°C, with a focus on analyzing trends and spatial distribution of six key climate variables. [Results] China's land surface warms faster than the global average, exhibiting amplified warming relative to global temperature rise. At 1.5?°C global warming, China’s annual mean temperature increases by approximately 1.3?°C, escalating to 5.92?°C under 5?°C warming. The minimum temperatures rises even more markedly, reaching 6.21?°C. The warming is particularly significant in Northeast China, North China, and the Qinghai-Tibet Plateau. Precipitation increases notably, with 70% of regions experiencing annual precipitation increases exceeding 50?mm relative to the baseline period under 3?°C warming, while the Tibetan Plateau and Northwest China receive over 100?mm more. Extreme high-temperature and extreme precipitation events are projected to intensify in both frequency and magnitude under higher warming scenarios. Wind speed and relative humidity display declining trends, potentially affecting wind energy utilization and regional moisture cycles. At 1.5?°C warming, wind speed decreases by about 0.15?m/s, nearly doubling to 0.32?m/s under 5?°C warming. Relative humidity declines by 0.34% compared to the baseline period at 5?°C warming, though substantial inter-model uncertainties persist. [Conclusion] These findings provide scientific support for climate adaptation and mitigation policies in China, emphasizing the critical need to constrain global temperature rise to address potential climate challenges and reduce future climate risks.
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Nonlinear Responses of Meadow Soil Microbial Activities to Increasing Numbers of Freezing-Thawing Cycles

HUANG Wei

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The meadow soil in the Tibetan Plateau is highly susceptible to freeze-thaw changes under future climate conditions, and hence this study aims to elucidate the responses of meadow soil microbial activities to increasing number of freezing-thawing cycles. [Methods] A meadow soil was collected from the seasonal FT region of the Tibetan Plateau. Five different FT scenarios respectively with 1, 3, 5, 7 and 9 FT cycles (hereafter termed as C1, C3, C5, C7 and C9) were simulated and compared with the non-FT treatment (N9), to identify the varying responses of dissolved organic carbon (DOC), NO3-N, NH4-H, soil microbial biomass carbon (SMBC) and nitrogen (SMBN), as well as CO2 and N2O emission rates. [Results] 1) Compared with the non-FT N9, the SMBC was significantly decreased by 23.64% after C9, while the DOC significantly increased by 10.7%, cumulatively releasing 71.10% and 321.40% more CO2 and N2O; 2) With increasing number of FT cycles, the DOC and the activities of β-glucosidase and leucine aminopeptidase showed nonlinear patterns, which declined first to the lowest values after C5 and then gradually increased at C7 and C9. The CO2 emissions rates peaked after C2 (1.83 times of that from the non-FT soil), whilst the N2O emission rates roared up after C5 (reaching 8.01 ~ 25.43 times of that from the non-FT soil). 3) With the increasing number of FT cycles, the SMBN did not vary significantly, yet the NO3-N and acetylaminoglucosidase activities gradually increased, while the NH4-N steadily decreased. [Conclusion] The effects of multiple freeze-thaw cycles on soil microorganisms were not just repetitions of a single freeze-thaw event. After five freeze-thaw cycles in alpine meadow soils, the changes in pore structure and microbial deaths induced by soil water freezing and swelling had been basically stabilized, while the surviving microbial communities gradually adapted to the new temperature conditions and revived their activities in further freeze-thaw cycles. This casted a new light to help advance our current understanding as to how soil microbes overwinter in the seasonal freeze-thaw regions.
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Effects of the Arbuscular Mycorrhizal Fungi Inoculation on Soil Properties of Plantations in Karst Rocky Desertification Areas

WANG Miaomiao

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[Objective] Clarifying the reduction mechanism of arbuscular mycorrhizal fungi (AMF) inoculation in insufficiency of soil nutrient and water supply, can realize the sustainable restoration of fragile karst ecosystems. [Methods] Based on the in-situ inoculation experiment in plantations in typical karst rocky desertification areas of Shaoyang County, Hunan Province, this study collected 0-15 and 15-30 cm fine roots and 0-15, 15-30, and 30-50 cm soil samples in different slopes (upper, middle, and lower slopes), to determine the infestation and community composition of AMF and physicochemical properties. Effects of key microorganism addition on soil properties such as nutrient and water were studied. [Results] The results showed that, inoculation increased the intensity and rate of AMF infestation in roots. At the generic level, Paraglomus, Glomus, and Ambispora were the dominant genera in AMF community composition. After inoculation, changes in their relative abundances were obviously and varied in different slopes and soil layers. Simpson diversity index in 0-15 cm increased at all slopes, while that in 15-30 cm increased only at middle slope and in 30-50 cm increased at middle and lower slopes, with no significant changes; all Chao1 richness indexes increased, but differed significantly only in 0-15 cm at upper slope; Pielou evenness index increased in 0-15 cm at upper and middle slopes, in 15-30 cm at middle slope, and in 30-50 cm at all slopes, with no significant changes. Alkali-hydrolyzed nitrogen (AN) concentration decreased in different soil layers, while available phosphorus (AP) concentration decreased only in 15-30 cm. Soil organic carbon concentration decreased in 0-15 and 15-30 cm, with no significant changes. Volumetric water content increased significantly in different soil layers. Capillary pores increased in 0-15 and 30-50 cm, with no significant changes. Values of pH and exchangeable Ca2+ decreased in all soil layers, with no significant changes. The ratios of AN∶AP decreased at 0-15 and 15-30 cm, indicating that the inoculation of AMF could alleviate the restriction of soil P to some extent. Correlation and redundancy analysis among soil properties showed that the changes in microbial community composition after inoculation could directly or indirectly affect soil physical and chemical conditions such as nutrient and water. [Conclusion] The results clarify the response characteristics of soil properties to AMF inoculation in plantations of rocky desertification areas, and clear the changes in nutrient and water with showing the drivers, which is helpful to break the bottleneck of soil ecological function restoration lag and improve the service function of fragile ecosystems.
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Effects of Different Straw Returning Methods on Runoff, Sediment Yield and Nitrogen-Phosphorus Losses in Purple Soil Sloping Farmland of Southern Sichuan

ZENG Xiewei, HE Binghui

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[Objective]To investigate the effects of different straw returning methods on runoff, sediment yield, and nitrogen-phosphorus losses in purple soil sloping farmland of southern Sichuan. [Methods] Runoff plots were established on typical purple soil sloping farmland with a slope of 15°. Five treatments were established: no straw mulch (CK), low straw mulch (T1: 3744 kg/hm2), high straw mulch (T2: 7488 kg/hm2), low straw mulch + decomposing agent (T3: 3744 kg/hm2 + 1.5 kg/hm2), and high straw mulch + decomposing agent (T4: 7488 kg/hm2 + 3 kg/hm2). Runoff, sediment yield, and nutrient loss were monitored under rainfall events. [Results] (1) Results showed that T3 had the best soil conservation effect, significantly reducing runoff depth (by 40.2%) and sediment loss (by 55.3%) while effectively mitigating nitrogen and phosphorus loss. (2) Correlation analysis revealed that nutrient loss was mainly controlled by runoff (p<0.01). However, the weakening nitrogen loss control effect of straw returning over time was attributed to increasing TN concentrations in runoff. (3) all treatments had TN/TP ratios below 22, indicating nitrogen limitation in this region. [Conclusion] Appropriate straw mulching combined with decomposing agent application effectively enhances soil-water conservation and nutrient utilization in purple soil sloping farmland of southern Sichuan, providing scientific basis for optimizing agricultural management practices.
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Effects of Microbial Agents on Soil Nutrients and Bacterial Community Structure in Wheat Fields of North China

sunjiajing, fuxin

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To investigate the effects of different types of microbial agents applied during the jointing stage of wheat in a wheat-maize rotation system on soil properties, a field experiment was conducted from 2022 to 2024. Four treatments were set up: a water control (CK), application of auxin-producing microbial agent (T1), application of microbial agent (T2), and application of biocontrol microbial agent (T3). The impacts of these agents on soil chemical properties, bacterial community structure, and wheat yield were examined. The results showed that in the 0-20 cm soil layer, the application of various microbial agents significantly improved soil chemical properties compared to CK. The T2 treatment had the most significant effect on increasing soil alkaline nitrogen and available phosphorus content, with increases of 22.60%-29.61% and 21.63%-37.51%, respectively, and a significant decrease in pH value, while there was no significant difference in available potassium content among all treatments. In the 20-40 cm soil layer, the available phosphorus content in the T2 treatment was significantly higher than that in CK by 22.05%, and there were no significant differences in pH value, organic matter, alkaline nitrogen, and available potassium content among all treatments. Compared to CK, the application of all microbial agents was conducive to increasing the α-diversity index of rhizosphere soil bacteria, with an increase of 2.59%-3.29%. The application of microbial agents significantly affected the relative abundance of dominant bacterial phyla in the soil. Ninety days after application, compared to CK, the relative abundance of Proteobacteria in the T1, T2, and T3 treatments increased significantly by 2.70%, 5.42%, and 3.71%, respectively, while the relative abundance of Gemmatimonadetes in the T2 treatment decreased significantly by 4.75%. The relative abundance of bacteria with biocontrol and growth-promoting functions in the rhizosphere soil of all microbial agent treatments was higher than that in the CK treatment, while the relative abundance of the pathogenic Nocardioides, which has disease-inducing effects, was significantly reduced at both 15 and 90 days. Compared to CK, the wheat yield in the microbial agent treatments increased significantly by 8.28%-20.43% in 2022-2023 and by 5.70%-16.23% in 2023-2024, with the T2 treatment showing the most significant effect. In conclusion, the application of microbial agents during the jointing stage of wheat effectively activated soil nutrients, enhanced bacterial diversity and the abundance of biocontrol/promotive function bacteria, and increased wheat yield, with the application of Pseudomonas fluorescens PM12 being the most effective.
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Dynamic Simulation of Production-Living-Ecological Space and Habitat Quality Based on MOP-PLUS in Hunan Province in the Next Ten Years

JIN Xinyv, ZHAO Xianchao

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[Objective] Hunan Province is an important node province of the Yangtze River economic belt. Exploring the future development of production-living-ecological space and evaluating the future habitat quality, taking into account economic and ecological development, plays an important role in the allocation of land space resources and ecological security management. [Method] Based on the land use data from 1990 to 2020, through the land use transfer matrix and dynamic degree analysis of the spatial composition of Hunan Province in the past 30 years, the multi-objective planning model was used to build different development scenarios. The PLUS and InVEST models were used to predict and analyze the land use changes in different development scenarios. [Results] ① from 1990 to 2020, the proportion of ecological space in Hunan Province was the largest, about 69.44%, followed by the production space, about 28.74%, and the living space was the smallest; The conversion of production space and ecological space is frequent. Although the conversion area of living space is small, the change range is the largest. ② In the four scenarios, the production and ecological space decreased, while the living space increased; Under the scenario of priority development of production and living space, living space has the fastest growth and the largest economic benefit, which is 1.23 times that of 2020; Under the scenarios of priority development of ecological space and natural development, the reduction of ecological space area is small, and the ecological benefits are 0.098% and 0.150% respectively compared with 2020, but the economic benefits are low; The balanced and coordinated development of production-living-ecological space scenario protects the ecological space while meeting the needs of regional development, taking into account ecological and economic benefits. ③ From 1990 to 2020, the habitat quality of superior grade in Hunan province accounted for the largest proportion, and the overall habitat quality was good, with little fluctuation and a downward trend. The simulated habitat quality decreased slightly in 2030. [Conclusion] the habitat quality of Hunan Province has little change in 2030, and the balanced and coordinated development scenario of production-living-ecological space takes into account economic and ecological benefits, which is suitable for the future development of the region.
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Impacts of Slope Erosion-Deposition Processes on Soil Organic Carbon Fractions in the Black Soil Region of Northeast China

ZHOU Xiao, WANG Bin

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[Objective]This study aims to investigate the impacts soil erosion-deposition processes on soil organic carbon (SOC) fractions and their underlying interaction mechanisms, to enhance understanding of carbon stock management strategies and SOC response mechanisms in the black soil region in Northeast China’s cultivated land. [Methods]The research focused on typical sloping farmland in Binxian County (thin-layer black soil) and Keshan County (thick-layer black soil). The 137Cs tracing technique was employed to quantitatively assess soil erosion intensity, clarify the differences and trends in SOC fractions under varing erosion intensities, and reveal the mechanisms underlying changes in SOC fractions induced by soil erosion. [Results]Results showed that the soil erosion modulus in the thin-layer black soil area was 2822.99 t/(km2·a), while in the thick-layer black soil area it was 2174.74 t/(km2·a). Soil erosion-deposition rates were found to be the primary drivers of SOC fractions changes. SOC fractions decreased significantly with increasing soil erosion rates, exhibiting a strong negative linear relationship. The loss rates of different SOC fractions were ranked as follows: EOC > POC > MBC > DOC. [Conclusion]Total nitrogen (TN) was identified as a key factor influencing the distribution of SOC and its fractions, while the C/N ratio, clay content, and sand content also had significant effects. These findings provide a scientific basis for carbon stock management and erosion control in the black soil region.
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Influence of Riverbed Sediments on the Infiltration-Clogging Process of Muddy Water and Improvement of the Infiltration Model

MIAO Qingyuan, PAN Chengzhong

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[Objective] Physical clogging of riverbeds is a common problem in seasonal rivers, which has a significant impact on groundwater recharge and river ecological restoration. Analyzing the infiltration and clogging characteristics of seasonal rivers and predicting the infiltration rate after the disconnection of the riverbed can provide a scientific basis for the subsequent optimization of river ecological restoration and water replenishment schemes. [Methods]Elected five types of riverbed materials (with median particle sizes d50 of 50, 100, 150, 300, and 600 μm) as media in the lower reaches of the Yongding River. A one-dimensional soil column infiltration simulation experiment was conducted using 6 g/L turbid water to analyze the characteristics of riverbed blockage and the transition law between saturated and unsaturated flow. A prediction model for riverbed infiltration process considering the influence of physical blockage was established. [Results] 1) The fine particle riverbed with a median particle size of 50 μm did not experience significant blockage, and the depth range of blockage in the 100～600 μm riverbed was 0～5 cm. The permeability coefficients decreased by 86%, 68%, 93%, and 94% respectively compared to the initial values. 2) The entire process of riverbed infiltration for a riverbed with a particle size of 50 μm is saturated seepage flow. For riverbeds with particle sizes ranging from 100 to 600 μm, the seepage flow transitions from saturated to unsaturated at 51.2 h, 9.6 h, 17.6 h, and 2.6 h respectively within the time range of approximately 2.6 to 51.2 h. The reduction in the infiltration rate is approximately between 15% and 30%. 3) A riverbed infiltration model considering the effect of blockage based on Darcy's law and coarse particle seepage formula was constructed. Model validation showed that the relative errors of the infiltration rates of four coarse particles (100～600 μm) riverbeds were 8.6%, 14.7%, 22.1%, and 36.6%, respectively, which increased with the increase of median particle size. [Conculsion] Fine sediment in muddy water has a relatively large impact on the clogging of coarse-textured riverbeds. The coarser the texture of the riverbed is, the more likely it is to transform into a disconnected riverbed. Scientifically understanding the infiltration-clogging laws of fine sediment in intermittent rivers with riverbeds of different textures is of great significance for the subsequent optimization of ecological water replenishment schemes.
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Construction of Water Ecological Security Patterns Based on Ecosystem Service Flows:A Case Study of the Mainstream of the Liao River

Lian Ling yu, Lu Xu

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The construction of water ecological security pattern is of great significance to the ecological protection, restoration and sustainable development of the basin. In this paper, we take the Liaohe River Basin as an example, and select three water ecosystem services with hydrological conductivity characteristics: water production, water purification and soil conservation. Based on the conceptual framework of “source-flow-sink”, we use the In VEST model to quantitatively assess the supply-demand relationship of the water ecosystem services in order to identify the sources and sinks, and the circuit theory to identify ecological corridors, ecological pinch points and obstacle points through the medium of water flow. The In VEST model was used to quantitatively assess the supply-demand relationship of water ecosystem services to identify sources and sinks, and the circuit theory was used to identify ecological corridors mediated by water flow, as well as ecological pinch points and obstacles, and to construct a watershed water ecological security pattern. The results show that the “sources” of the three water ecosystem services cover an area of 12,200 square kilometers and the “sinks” cover an area of 0.49 million square kilometers, while the “streams” form 287 service streams in the form of trees and networks, with a total area of 1,000 square kilometers. There are 287 network-like service streams, mainly along the dry river to the tributaries; there are 79 ecological pinch points and 111 ecological obstacle points. The results of the study can provide a basis and strategy for the classification of watershed ecological restoration zones, identification of key areas, and layout of restoration projects.
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The Characteristics and Influencing Factors of the Variation in Soil Organic Carbon Components and Stability in the Arid River Valleys of Southeastern Tibet

chubaosen, zhoujinxing

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[Objective]This study investigates the variation characteristics of soil organic carbon components and their stability in arid river valley regions, identifies the factors influencing these components and their stability, and provides a foundation for the systematic management of carbon sequestration and emission reduction in ecologically fragile areas.[Methods]Soils from the 0-30 cm depth of different slope aspects (shady slope, sunny slope, semi-shady slope, semi-sunny slope) and different slope positions (lower slope, middle slope, upper slope) in the arid river valley of Bomi, Tibet, were selected as the research subjects. The physicochemical properties, soil organic carbon, and its component contents were measured.[Results](1) The SOC content in north-facing slopes ranged from 11.37 to 34.74 g/kg, which was 55%, 138%, and 292% higher than that in semi-shady, semi-sunny, and south-facing slopes, respectively. The SOC content decreased along the slope positions, with the distribution order being lower slope (17.29 g/kg) > middle slope (13.42 g/kg) > upper slope (9.73 g/kg).(2) SOC components, including particulate organic carbon, easily oxidized organic carbon, mineral-associated organic carbon, and soluble organic carbon, all showed an increasing trend from south-facing to north-facing slopes. In contrast, SOC components exhibited a decreasing trend with increasing slope position.(3) The stability of SOC in north-facing slopes ranged from 54.3% to 62.1%, which was 6%, 12%, and 30% higher than that in semi-shady, semi-sunny, and south-facing slopes, respectively. The stability of SOC varied among slope positions in the order of lower slope (38.1%–62.1%) > middle slope (36.9%–59.9%) > upper slope (37.6%–58.7%).(4) Correlation analysis indicated that total nitrogen, alkali-hydrolyzable nitrogen, and particle size distribution significantly influenced SOC components. Total nitrogen, mineral-associated organic carbon, and soluble organic carbon significantly affected SOC stability. Redundancy analysis revealed that soil alkali-hydrolyzable nitrogen, carbon-nitrogen ratio, and clay content were the main factors influencing SOC components and their stability under different slope aspects and positions.[Conclusion]The results indicate that both slope aspect and slope position have a significant impact on soil organic carbon components and their stability, with soil nitrogen content and particle size composition being the primary influencing factors. These findings provide a scientific basis for the scientific management of arid river valleys and the implementation of regional carbon neutrality strategies.
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ffects of Biochar Combined with Nitrification/Urease Inhibitor and Straw Mulching on Nitrogen and Phosphorus Leaching in Red Soil Tea Plantation

LIAO Qiyuan

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[Objective] To investigate the effects of biochar combined with nitrification/urease inhibitors and straw mulching on nitrogen and phosphorus leaching in tea plantations under field conditions, this study aims to provide a scientific basis for controlling nitrogen and phosphorus leaching in tea plantation. [Methods] In this study, a tea plantation in red soil hills in subtropical areas was selected as the research object. Five treatments were set: no fertilization (CK), conventional fertilization (CON), addition of biochar (BC), biochar and nitrification inhibitor and urease inhibitor (BNI) and straw mulching (RS). During the one-year observation period, the soil properties change and leaching losses of nitrogen and phosphorus under natural rainfall conditions were monitored. [Results] During the observation period, compared with CON treatment, the mass fraction of ammonium nitrogen and nitrate nitrogen in soil treated by BNI was the highest and was 2.8% and 72.8% higher, respectively. The high mass fraction of ammonium nitrogen and nitrate nitrogen in soil treated by BNI promoted the increase of total nitrogen concentration in leaching solution. Soil nitrogen and phosphorus leaching in each treatment mainly occurred in the rainy period of spring and summer. The leaching coefficient of BC treatment was the highest (24.3%), and that of RS treatment was the lowest (8.3%). As for the total nitrogen loss of leaching solution, BNI treatment (275.0 kg/hm2) was the highest, RS treatment (65.9 kg/hm2) was the lowest; As for the total phosphorus loss in the leaching solution, the loss form was mainly granular phosphorus, the highest in BC treatment (201.5 g/hm2) and the lowest in RS treatment (32.4 g/hm2). Compared with CON treatment, the total nitrogen loss of RS treatment solution was reduced by 43.6%. The total phosphorus loss of BNI and RS treatment was reduced by 39.1% and 77.2%, respectively. [Conclusion] Combining the available nutrient content of soil plants in tea plantation and the control ability of nitrogen and phosphorus leaching, straw mulching is an effective management measure to reduce nitrogen and phosphorus loss in tea plantation.
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Modeling of the Constitutive Relationship Based on the Mixture Law for Vetiver - Laterite Composites at Different Growth Stages

Wu Ruibin, Ji Jinnan

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[Objective] To construct a constitutive model suitable for the vetiver grass-soil composite at different growth stages, for the precise simulation and prediction of its mechanical behavior. [Method] This study selected vetiver grass-lateritic soil composites at three growth stages (20 days, 40 days, and 60 days) as the research subjects, and mechanical data were obtained through triaxial tests. Based on the mixture rule, the Duncan-Chang model and the linear elastic model were employed to calculate the constitutive relationships of the soil and plant roots, respectively, and these were superimposed according to the volume fraction. [Results] (1) The two-phase superimposed constitutive model constructed based on the mixture theory demonstrated excellent performance in simulating the mechanical behavior of the root-soil composite (R2 > 0.89). The stress-strain curves of the model accurately reflected the shear strength of the root-soil composite in triaxial tests and the variation trends of stress-strain relati
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Effect of flooding restoration on soil organic carbon storage in soda saline-alkali degraded wetland

Feng Weihui, Wen Bolong

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[Objective] In order to scientifically evaluate the eco-environmental effects of inland degraded saline-alkali wetlands after restoration, and to analyze the changes of soil organic carbon content and reserves after restoration. [Methods] Selected typical marsh wetlands degraded for many years (alkali spot land, Leymus chinensis grassland) and flooded phragmites australis swamp land in the western part of Songnen Plain as study sample plots. Based on the measurement of aboveground-underground biomass, physical and chemical properties and nutrient content of 1 m underground soil profile, the changing rules and influencing factors of SOC content and storage in degraded saline-alkali wetland were analyzed and discussed. [Results] after restoration, the vegetation biomass and carbon pool of phragmites australis wetland were 8446.54 g·m-2 and 1.90 kg·m-2 respectively, which increased by 422.68% and 216.67% respectively compared with Leymus chinensis grassland. The vegetation biomass and carbon pool of alkaline spot land were 0, and those of Leymus chinensis grassland were 1616.00 g·m-2 and 0.60 kg·m-2, respectively. Flooded restoration of degraded wetlands promoted the increase of vegetation biomass and carbon storage. After restoration, the organic carbon storage in 1 m soil profile of phragmites australis marsh wetland was 17.38 kg·m-2, which was 64.12% and 4.45% higher than that in alkali spot land and Leymus chinensis grassland, 10.59 kg·m-2 in alkali spot land and 16.64 kg·m-2 in Leymus chinensis grassland. Flooded restoration of degraded wetlands promoted the increase of soil organic carbon storage. The content of soil organic carbon in the deep soil of the degarded and restored wetlands was higher than that in the surface layer, the growth of vegetation increased the content of soil organic carbon, and the gaps and flooding between soil particles promoted the migration of organic carbon to the deep layer. The content and storage of SOC were positively correlated with soil water content, and negatively correlated with total nitrogen, total phosphorus, electrical conductivity and the ratio of nitrogen to phosphorus. There were significant differences in soil physical and chemical properties among alkali spot, Leymus chinensis grassland and phragmites australis wetland. The content of SOC was affected by soil environmental conditions and the improvement of soil environment in the restoration process of degraded wetland. It is beneficial to the accumulation of SOC. [Conclusion] The flooding restoration of soda saline-alkali degraded wetlands is conducive to the realization of the goal of "double carbon".
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Study on the Spatial-temporal Evolution of Vegetation and the Spatial Heterogeneity of Its Influencing Factors in the Chaohu Basin from 2000 to 2023

wanghao, Don Bin

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[Objective] This study aims to monitor the fractional vegetation coverage (FVC) in the Chaohu Basin and analyze the spatial heterogeneity of its influencing factors, providing scientific support for environmental protection and water resource management in the region. [Methods] The FVC from 2000 to 2023 in the Chaohu Basin was calculated using the Google Earth Engine (GEE) platform. The Theil-Sen Median slope estimator, Mann-Kendall trend test, coefficient of variation, and Hurst index were applied to analyze the variation characteristics and trends. The geographic detector and Multi-scale geographically weighted regression (MGWR) were used to explore the spatial heterogeneity of vegetation temporal and spatial changes and their influencing factors, with results visualized. [Results] (1) The area proportion of FVC > 0.4 in the Chaohu Basin is 60.96%. Over the 24 years, FVC showed an upward trend, with 58.21% of the area improving overall. However, there is a potential risk of FVC degradation in the future. (2) The geographic detector analysis indicated that all influencing factors were significantly related to FVC. Interaction detection revealed that the interaction of two factors significantly enhanced the explanatory power for FVC. (3) MGWR results showed that different influencing factors had significant spatial variations in their effects on vegetation in the Chaohu Basin. (4) Different influencing factors showed varying scales of impact on FVC in the Chaohu Basin, with GDP, sunlight duration, and elevation as global variables, and other factors as local variables. [Conclusions] This study effectively reveals the spatial heterogeneity of different influencing factors, providing quantitative and theoretical support for ecological protection in the Chaohu Basin and promoting sustainable development in the region.
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Study on the Characteristics and Spatio-temporal Patterns of Forest Ecosystem Service Value in Fujian Province Based on Remote Sensing Assessment

yechuan, hongyanzhen

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As one of the most important natural ecosystems on the earth, forest ecosystems provide multiple service values such as supply services, support services, regulation services and cultural services. Fujian Province is rich in forest resources and is a pioneer demonstration zone for ecological civilization construction. Therefore, it is of great practical significance for Fujian Province to clarify the status of forest ecosystems and integrate spatial configuration in formulating scientific and reasonable ecological protection and management policies and promoting regional sustainable development. Based on the spatio-temporal perspective of geography, this paper takes the forest ecosystem service values of Fujian Province in 2000, 2003, 2008, 2013, 2018 and 2023 as the research object, uses the value equivalent method and makes three coefficient corrections to calculate the forest ecosystem service values of Fujian Province in the corresponding years. Finally, the ArcGIS gravity center model, spatial analysis and other model methods are used to analyze the evolution of the spatio-temporal pattern. The results show that: (1) The forest ecosystem in Fujian Province has a wide coverage area, and the total area shows a trend of first increasing and then decreasing, with a relatively balanced distribution. However, the forest ecosystem is gradually becoming more dispersed, and the degree of fragmentation is deepening. (2) The forest ecosystem service value in Fujian Province shows a fluctuating change trend, with a slight decrease in the total value, but the change degree is small. The regulation service value is the main part of the forest ecosystem service value, and the change trend is basically consistent with that of the forest ecosystem service value. In addition, the spatial regional distribution law of forest ecosystem service value grades in different stages is obvious, and the grade distribution of each county and district in different periods is different. (3) The spatial distribution pattern of forest ecosystem service value in Fujian Province shows a "northeast-southwest" spatial distribution trend, and the distribution center generally moves to the southwest, gradually deviating from the geometric center of Fujian Province. The coverage of the standard deviation ellipse is relatively stable, and the spatial distribution balance gradually strengthens. (4) The forest ecosystem service value in Fujian Province shows a spatial distribution characteristic of high-high aggregation or low-low aggregation, and the spatial aggregation effect of high-high and low-low types of forest ecosystem service value is relatively significant, while the spatial aggregation effect of low-high and high-low types is not obvious.
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Response of organic carbonation molecular structure of soil aggregates to nitrogen and phosphorus addition in evergreen broad-leaved forest

WANG Pingxiu, ZU Kuiling

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[Objective]Soil organic carbon (SOC) not only helps to maintain soil health, but also plays an important role in regulating global climate change. At present, the effects of nitrogen (N) and phosphorus (P) additions on soil aggregate carbon and their underlying mechanisms are still unclear. To reveal the effect of N/P addition on soil aggregate carbon in subtropical evergreen broad-leaved forests and its internal mechanism is of great significance for understanding soil organic carbon stability and ecosystem carbon cycle in subtropical evergreen broad-leaved forests. [Methods]N and P addition test platforms were set up in evergreen broad-leaved forest for 6 years (control, 100 kg N hm-1 a-1，50 kg P hm-1 a-1，100 kg N hm-1 a-1+50 kg P hm-1 a-1). The response of soil organic carbon with different particle sizes to N deposition and P addition was investigated by analyzing the particle size classification, phosphorus composition and molecular structure of organic carbonation. [Results] Nitrogen (N) addition significantly increased the content of soil organic carbon (SOC) in macroaggregates (>2 mm) and clay and silt particles (<0.053 mm), and significantly reduced the degree of soil organic carbon decomposition (SD) in macroaggregates (>2 mm) and small aggregates (0.25-2 mm). The combined application of nitrogen and phosphorus (N+P) significantly increased the content of polysaccharides and alcohols and phenols in macroaggregates (>2 mm), significantly reduced the degree of soil organic carbon decomposition (SD) in small aggregates (0.25-2 mm), and significantly increased the content of resin (Resin-P) in soil easily degradable phosphorus of various particle sizes except microaggregates (0.25-0.053 mm). Redundancy analysis showed that NaOHs-Pi and residual phosphorus were the main drivers of the chemical molecular structure of >2 mm and <2 mm aggregates, respectively. [Conclusion] N deposition accelerated soil C sequestration by enhancing the formation of refractory state P and thus the stability of the chemical molecular structure of soil aggregates.
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Al2(SO4)3-straw improvement on nitrogen conversion mechanism in soda-saline-alkali soil

Yu Li

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[Objective]In order to study the effect of Al2(SO4)3 combined with organic materials on the nitrogen conversion mechanism in saline-alkali soil, and to reveal the effects of different application ratios on soil nitrogen pool. [Methods]Three Al2(SO4)3 gradients accounting for 0.2%A0.2，0.1%A0.1 and 0%A0 of soil weight and three straw gradients acco unting for 1%S1，0.6%S0.6 and 0%S0 of soil weight were set up in the west of Jilin Province. Soil NH4+-N content, NO3--N content, urease and protease activity were measured respectively under the conditions of nitrogen fertilizer and no nitrogen fertilizer.[Results]The introduction of Al2(SO4)3 improved the average net mineralization and nitrification rate, with the performance of A0.2S0>A0.1S0, and the mineralization and nitrification gradually decreased with the incubation time. The addition of straw hinders soil nitrogen mineralization and nitrification. After the application of urea, the average net mineralization rate and nitrification rate increased accordingly by 17.34 times and 3.61 times, respectively, after urea application, but it was still inhibitory. The addition of Al2(SO4)3 combined with rice straw (A0.1-0.2S0.6-1) further inhibited the conversion of soil nitrogen. The introduction of Al2(SO4)3 into high quantity rice straw (S>0.6) accelerated the decrease of the decrease in soil NH4+-N and NO3--N was alleviated by the application of nitrogen fertilizer. With the increase of Al2(SO4)3, the contents of ammonium nitrogen and nitrate nitrogen increased, as A0.2S1>A0.2S0.6>A0.1S1. The interaction between Al2(SO4)3 and rice straw had significant effects on urease, protease activity, soil total nitrogen, soil NH4+-N content and soil NO3--N content under the condition of no urea application, and showed extremely significant effects after urea application. There were significant positive correlations between urease and protease activity in soil and total nitrogen content, between NH4+-N and NO3--N, and between net mineralization rate and nitrification rate.[Conclusion]Combined application of Al2(SO4)3 with high rice straw retained more nitrogen from the soil, A0.2S1 treatment had the best nitrogen utilization effect.The research results can provide reference for the improvement and treatment of saline-alkali soil, and provide theoretical support and practical guidance for future research and practice.
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Spatiotemporal Variation Characteristics of Soil Water Storage and Their Influencing Factors on a Larch Plantation Hillslope in Liupan Mountains

liushan, liuxiaofen

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Abstract：[Objective] The difference of soil moisture distribution along hillslopes lead to significant spatial variability in soil water storage (SWS) due to variations in meteorological conditions, vegetation characteristics, soil properties and topographic features. However, the current understanding of soil moisture dynamics and their influencing factors at different slope positions on forested hillslopes remains insufficiently systematic. [Methods] A comprehensive field investigation was conducted on a representative larch plantation hillslope in the semi-humid Liupan Mountains. From May to October 2023, we monitored the spatiotemporal dynamics of soil volumetric water content in the 0-80 cm soil layer at upper, middle and lower slope positions. Concurrent measurements of meteorological conditions, vegetation structure and soil physical properties were carried out to support the analysis. [Results] (1) There were slope differences in soil water storage (SWS), with the mean values of middle slope > lower slope > upper slope. However, the fluctuation of SWS was greatest on the upper slope. (2) Temporally, the incremental changes in SWS in the 0-80 cm soil layer were highly variable at all three slope positions during a single rainfall event. Among different layers, the SWS in the 0-10 and 10-20 cm soil layers demonstrated relatively lower variability. The temporal variation of SWS increments was primarily influenced by rainfall amount and duration. The variation in SWS reduction in the 0-80 cm soil layer was also highly variable at all three slope positions during a single rain-free period. Among different layers, the SWS in the 10-20 cm soil layers displayed the least variability. The temporal variation of SWS reduction was mainly governed by potential evapotranspiration and the duration of rain-free days. (3) Spatially, SWS increment magnitude followed middle slope > lower slope > upper slope, mainly related to soil bulk density and saturated hydraulic conductivity. The of SWS reduction magnitude followed middle slope > upper slope > lower slope, mainly related to stand evapotranspiration, gravel volumetric content, and total porosity. [Conclusion] These findings provide valuable insights into the mechanisms of soil water redistribution on forested hillslopes and offer scientific guidance for sustainable forest-water management in semi-humid mountainous regions.
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Morphological and Spatial Distribution Characteristics of Niches on Collapsing wall in Benggang Erosion Area in the Southeast Guangxi

Luo Shuyu, Deng Yusong

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IThe formation and development of niches in collapsing walls exacerbate the erosion of Benggang and threaten land resources and ecological environment. This study investigated the spatial distribution and morphological characteristics of niches in typical Benggang, analyzed their distribution patterns and evolutionary characteristics, and aimed to explore the impact of niches on Benggang. The results showed that: (1) Niches are mainly located in the lower part of collapsing walls, accounting for 45.83%, and 90.28% are developed in the sandy layer, with an angle of 30-50° (50.69%). (2) Niches have strong variability in morphological parameters, with 90.97% of the niches having a flattening ratio greater than 0.1, mainly showing elliptical and extremely elliptical shapes, 70.80% of the niches having a length-to-depth ratio and a short-to-depth ratio greater than 1, and 22.20% having a length-to-depth ratio greater than 1 and a short-to-depth ratio less than 1, reflecting that their plane morphology is mainly vertical axis extension, and the evolution stage is affected by lateral widening. (3) There is a highly significant positive correlation between the long axis, short axis and concave depth of the niche (P<0.01), and the length-depth ratio and the short-depth ratio can indirectly affect each other and jointly affect the morphological development of the niche. This study reveals the development characteristics and spatial distribution characteristics of the collapsed wall niche, providing a theoretical basis for the prevention and control of niche and collapsed ridge erosion.
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Study on the Interactive Relationship and Coordination Effect between Urban Green Land Use Efficiency and High-Quality Development in Yangtze River Delta Region

Ma Ming

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[Objective] To explore the interactive relationship and coordination effect between urban land green utilization efficiency and urban high-quality development, so as to provide scientific support for promoting the transformation of urban land green utilization and realizing regional high-quality development. [Method] Taking 41 prefecture-level cities in the Yangtze River Delta region as the object, we constructed the evaluation index system, measured the indexes of urban land green utilization efficiency and high-quality development from 2008 to 2022 by using the non-expected output Super-EBM and the entropy value-TOPSIS model, and revealed the interaction relationship between the two by using the PVAR model, with the help of the revised coupling and coordination model and the GM(1,1) gray model. The PVAR model is used to reveal the interaction between the two, and the modified coupling coordination model, GM (1,1) gray prediction model are used to explore the spatial and temporal characteristics of the coupling coordination and future trends. [Results] (1) The green land use efficiency of urban land in the Yangtze River Delta (YRD) region is “M-shaped” fluctuating and rising, presenting the spatial characteristics of “west retreating, east advancing, and pan-homogenization”; the non-linear growth characteristics of high-quality development are obvious, and “polarization radiation - trunk line extension” is the most important feature of urban land use efficiency. Polarization radiation - trunk line extension” spatial pattern is prominent. (2) There is a two-way causal interaction between the two, and at the same time by their own and each other"s double impact, but more influenced by their own structure, with inertial dependence characteristics, and high-quality development of urban land green utilization efficiency is more effective. (3) The level of coupling and coordination of the two systems is growing steadily, with Shanghai > Jiangsu > Zhejiang > Anhui, generally showing the spatial characteristics of “high in the south and low in the north, high in the east and low in the west, and rising in the center”, and the pattern of the “Z-shaped” axes with the developed cities as the core is becoming clearer; the future is bright. The level of coordination will continue to improve, but the “core-edge” distribution pattern will be consolidated. [Conclusion] By closely following the “five development concepts”, updating the land use management mode and integrating the interaction and symbiosis between the two, the coordinated development of the region will be promoted.
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Development process and structure characteristics of physical crust of typical Quaternary red clay in southern region

Xu Huiyun, Zhu Xuchao

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[Objective] Objectively quantify the physical crust development process and explict the development process and structure characteristics of physical crust of Quaternary red clay (QRC). [Methods] The study utilized an artificial rainfall simulation experiment to obtain soil crust samples under different rainfall duration. CT scanning and the threshold of soil porosity were employed to quantify the thickness of crust, which served as an indicator of the process of physical crust information and reveal the development process of QRC. Additionally, we examined the structural properties of soil samples with varying degrees of crust development by extracting two-dimensional (2D) and three-dimensional (3D) pore indicators from the soil crust samples. [Results] (1) The formation of QRC’s physical crust can be divided into separate phases. These stages can be summarized as follows: the initial stage involves particles spreading out to occupy the empty spaces in the soil; the second stage involves droplets coming together and becoming more compact; the third stage is when the soil becomes stable; and the fourth stage is when erosion takes place. The average thickness of the physical crusts in the QRC increased with time during rainfall, with values of 7.75, 8.07, 10.83, 11.53, 11.49, and 6.35 mm at 1, 10, 30, 60, 90, and 120 minutes, respectively. Except for the final result, the developing process (1-90 min) can be represented by the one-dimensional cubie equation y=10.17-4.69x+2.49x2-0.30x3 fitted (R2=0.8823). (2) The QRC physical crusts exhibited distinct 2D and 3D structural features at various phases of development. In the mid-development stage, the 2D indicators often show a steady decrease in pore number, porosity and equivalent of diameter, along with a gradual increase in circularity. The 3D indicators exhibited a pattern of the fractal dimension initially expanding and the stabilizing. In contrast, the pore surface area and connectivity of density showed an initial increase followed by a decrease. Each measure exhibits varying degrees of substantial disparities during different phases of crustal evolution. (3) "X-ray computed tomography and porosity threshold" can objectively quantify the thickness of physical crust, and indicate the development process of physical crust according to the change of crust thickness and pore structure characteristics. [Conclusion] The results provide a basis for investigating hydrological phenomena and precisely modeling erosion in regions afflicted by significant soil compaction.
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Investigating Trade-offs, Synergies, and Attributions of Ecosystem Services in the Yarlung Zangbo River Basin

Shi Xiaorui

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[Objective] The ecological environment of the Yarlung Zangbo River Basin is fragile. Revealing the spatiotemporal changes in the ecological service functions of the river basin and the trade-off and synergy of dominant functions can provide scientific and technological support for the ecological protection and restoration of the river basin. [Methods] Five critical ecosystem services (habitat quality, water production, soil conservation, carbon sequestration and food supply) were quantitatively assessed within Yarlung Zangbo River Basin using InVEST model. To analyze the spatiotemporal dynamics of ecosystem service functions across various altitudinal gradients and scales, and uncovers the tradeoffs and synergies among these services, Spearman non-parameter correlation analysis and geographical weighted analysis were employed. [Results] (1) From 2000 to 2020, the high values of five ecosystem services supply primarily concentrated in the lower reaches. The Yarlung Zangbo River Basin exhibited higher habitat q
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Health assessment of forest ecosystem in mountainous area of Beijing

doutingting, niujianzhi

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[Objective] To reveal the spatial and temporal evolution characteristics of the health status of forest ecosystems in the mountainous areas of Beijing from 2005 to 2020, and to analyze the regional differences and the explanatory power of the influencing factors.[Methods] We constructed a forest ecosystem health evaluation model with “geographic environment-vegetation structure-ecological pressure-vegetation function” as the criterion layer, and applied the entropy weight-TOPSIS method to calculate the weights of the indicators and evaluate the forest ecosystem health of the mountainous regions of Beijing year by year, and analyze the characteristics of the changes in the forest ecosystem health in 2005, 2010, 2015, 2020, and the changes in the forest ecosystem health of the mountainous regions of Beijing. We analyzed the changes of forest ecosystem health in 2005, 2010, 2015 and 2020.On this basis, spatial autocorrelation analysis and K-means clustering analysis were used to explore the spatial aggregation and regional differences in ecosystem health, and the explanatory power of each indicator factor on the spatial distribution of forest ecosystem health was quantified by using the single-factor detection and interaction detection modules in Geographical detector model.[Results]:(1) From 2005 to 2020, the health level of forest ecosystems in the mountainous areas of Beijing will show an upward trend year by year.At this stage, the forest ecosystems in the mountainous areas of Beijing are mainly moderately healthy and relatively healthy, with the proportion of the area in the two areas being 41% and 48%, respectively.The spatial pattern of spatial differentiation is high in the far urban areas and low in the near urban areas. (2) The health status of forest ecosystems in the Beijing mountainous area has been improving year by year, and the change was especially obvious from 2015 to 2020, with the proportion of excellent healthy areas rising from 2.43% to 18.65%.The Moran index in the study area showed a decreasing and then increasing trend from 2005 to 2020, exhibiting significant global spatial autocorrelation and local spatial autocorrelation clustering characteristics.The spatial types of significance were dominated by positive correlation, with 41.8% and 30.8% of HH and LL types, respectively, accounting for 79.6% of the total number of significance types. (3) Soil conservation, LAI, NDVI, tree cover, and population density were the dominant factors of forest ecosystem health in the mountainous areas of Beijing, and the interactions among the factors showed nonlinear enhancement and two-factor enhancement;Forest ecosystem health in Beijing"s mountainous areas was dominated by GDP and soil retention in 2005, by LAI and soil retention in 2010-2015, and by air purification and soil retention in 2020.[Conclusions] From 2005 to 2020, the health of forest ecosystems in the mountainous areas of Beijing has continued to improve, but 27.27% of the area is still in poor or moderate ecological health, with some room for improvement. The spatial distribution of areas with poor health and low-low catchment areas is basically the same, and the construction of ecological protection and restoration projects in forest belts should be strengthened in order to safeguard the ecological health of regional forests.In future forest management and care, the enhancement and maintenance of forest ecosystem services need to be fully considered.
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Effects of scutellaria-residue organic fertilizer on soil bacterial diversity and function in potato fields with continuous cropping on sandy land.

DU Chen-lu, WANG Hong-lei

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[Objective]Exploring the effects of scutellaria-residue organic fertilizer on the basic characteristics and microbial community diversity and function of continuous potato soil can provide theoretical references for the resource utilization of Scutellaria-residue and the soil improvement of continuous cropping potato fields. [Methods] Three kinds of organic fertilizer systems were constructed with the bulk medicinal herb Scutellaria-residue and sheep manure (mass ratio 1:4) as the base material, which were 3% of bacterial additive (F1), 5% of bacterial additive (F2), and 10% of bacterial additive (F3). The effects of three Scutellaria-residue organic fertilizer systems on the chemical properties, soil bacterial diversity and community structure of potato surface soils in continuous cropping were analyzed in conjunction with a controlled field trial.[Results](1)Compared with the control group,all three scutellaria-residue organic fertilizer systems significantly increased the available phosphorus and available potassium contents of the soil at the maturity stage by 8.12~12.00 mg.kg_-1^{and 65.63}~88.36 mg.kg_-1^{, respectively;}(2) and the total number of bacterial flora in the potato topsoil was increased by 60.96% in both F1 and F2 treatments, 23.19%, and enriched with beneficial genera such as Sphingomonas, Pseudoxanthomonas and Flavobacterium; (3)LEfSe analysis showed that the application of scutellaria-residue organic fertilizers suppressed the absolute abundance of pathogenic bacteria such as Pectobacterium in the soil, and enriched more beneficial bacterial communities with soil carbon and nitrogen cycling functions at significantly higher absolute abundances;(4) the three kinds of scutellaria-residue organic fertilizer systems were able to change the function of the soil bacterial mediated carbon and nitrogen cycle, and increase the soil bacterial flora on the organic matter decomposition potential of soil flora.[Conclusion] The application of scutellaria-residue organic fertilizer can improve the soil available phosphorus and potassium nutrient content, the abundance of beneficial bacterial genera and bacterial functional activity.
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Radar Detection Analysis of the Effect of Land Preparation Measures on Soil Moisture in Hilly Sloping Farmland in Guangxi

nixiaoqing, chenxiaobing

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[ Objective ] Soil preparation is a key measure in agricultural production in hilly and mountainous areas. It is of great significance to clarify the response relationship between the change of soil properties after soil preparation and the spatial variation characteristics of soil moisture in the field for improving the efficiency of agricultural production.[ Method ] Two typical land preparation measures of horizontal and reverse slopes in hilly and mountainous areas of Guangxi were taken as the research objects. The field radar detection experiment was combined with the indoor soil analysis experiment, and the effects of land preparation measures on the variation characteristics of soil moisture in sloping farmland were discussed in depth by means of image analysis and statistical analysis. [ Result ] Under the same external water supply conditions, the spatial variation of soil moisture after horizontal soil preparation significantly occurred in the range of 0-30 cm soil depth. The reverse slope preparation was concentrated in the range of 20-40 cm soil depth, and the slope farmland ran through the whole range of 0-50 cm soil depth. The spatial distribution of soil moisture in the field of horizontal soil preparation was the strongest ( average deviation degree was 0.0519 ), and the change degree of soil preparation on the reverse slope was the weakest. The spatial movement of soil moisture in the field of horizontal land preparation was stable ( reflection coefficient 0.33, instantaneous power change rate 8.41×10_¹¹ dB/ns ) and relatively uniform ( radar structure similarity index 0.78 ), while the degree of soil moisture movement in the field of reverse slope land preparation and slope farmland was relatively intense, and the spatial movement state changed greatly. The spatial variation of soil moisture in slope farmland was the largest ( comprehensive index 1.45 ), followed by reverse slope preparation ( comprehensive index 1.53 ), and the spatial variation of soil moisture in horizontal preparation was the smallest ( comprehensive index 1.57 ), and the soil moisture environment was relatively stable. Compared with slope farmland, the soil silt content after soil preparation has the greatest influence on the spatial variation of soil moisture. [ Conclusion ] Under the same external water supply environment, the soil moisture condition in the field after horizontal and reverse slope land preparation is better than that in the slope farmland, and the soil moisture storage condition in the field after horizontal underground preparation is relatively better.
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Progress in the study of the effect of mycorrhiza on soil respiration

ZHENG Xiang

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As a bridge between plants and soil, mycorrhizal play a crucial role in regulating the balance of soil carbon (C) pools. Mycorrhizae, by absorbing mineral nutrients from the soil in exchange for C fixed by plant photosynthesis, also contribute to soil C loss through respiration.S The role of mycorrhizal in soil carbon input, carbon stability, and carbon sequestration is well understood; however, knowledge of the effects of mycorrhizal on soil respiration is relatively limited. A review of the effects of mycorrhizal on soil respiration and their regulatory factors is presented. Using the mesh exclusion method, researchers have successfully isolated and quantified mycorrhizal respiration, and found that it accounted for an average of 16.8% of soil respiration. Specifically, arbuscular mycorrhizal respiration and ectomycorrhizal respiration contribute 18.4% (2.5%-32.0%) and 15.1% (3.0%-62.1%) to soil respiration, respectively. Inoculated mycorrhizal plants increased soil respiration by an average of 26.0% compared to mycorrhizal-free plants. The response of mycorrhizal respiration to soil temperature and soil moisture varied in different ecosystems, with mycorrhizal respiration appearing to be more sensitive to changes in soil moisture. Soil nutrient availability regulates the symbiotic relationship between mycorrhizal fungi and plants by affecting the nutrient acquisition strategies of plants, and then regulates mycorrhizal respiration. Biological factors such as fine root biomass, extraradical hyphal length density, and plant-supplied substrates also significantly influence mycorrhizal respiration. As an important component of both soil respiration and autotrophic respiration, mycorrhizal respiration contributes substantially to soil C loss, which cannot be overlooked. More precise methods are needed to isolate and quantify mycorrhizal respiration to accurately assess the dynamics of soil carbon cycling and provide scientific insights for global C management and climate change mitigation.
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Microtopographic Changes of Slopes under Different Planting Patterns and The Responses to Rill Development in the Alpine Canyon Areas of Western Sichuan

Shi Xiaopeng, 何淑勤

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Rill erosion constitutes a significant mode of erosion in slope farmlands. To elucidate the impact of diverse planting patterns on the morphological characteristics of rills, this study aims to identify appropriate planting strategies for specific regions.In order to investigate the characteristics of rill erosion on slopeSfarmland with various planting patterns in alpine canyon areas, this study selected several primary planting configurations as research subjects: Zanthoxylum +Plum+Candian fleabane, Zanthoxylum+Cherry +Artemisia indica,SZanthoxylum+SGreenSbean,SPlum+Soybean,San dSthe bare slope was used as a control. The erosion evolution and morphological parameters of hillslope rills underSdifferentSscour dischargeSratesS(6,S10SandS14SL.min_-1^,Srespe ctively) were analyzed utilizing in situ runoff plot scour tests combined with the Structure from Motion (SfM) technique. STheSresultSshowedSthat (1) Under conditions of rill erosion, the eroded area of the slope and the proportion of grid in the southern slope direction for various planting patterns are smaller than those observed on bare slopes. Under conditions of small to medium flow, the surface roughness exhibited a decreasing trend. Additionally, the proportion of grids within the range of 15° to 25° has increased, while the proportion of grids in the range of 60° to 90° has decreased. (2) Compared to the bare slope, the confluence morphology exhibited by various planting patterns is dendritic in nature and displays distinct fractal characteristics. With the exception of the 10 L.min_-1^{flow rate, the slope fractal dimension} D for the Zanthoxylum+Plum+Candian fleabane exhibited the highest value. It has a good sand reduction effect. The rill density across all planting patterns surpassed that of the bare slope, while the ratio of rill width to depth was lower than that observed in the bare slope, except for the combinations of Zanthoxylum+SGreenSbean and Plum+SoybeanSunder a scour flow rate of 10 L.min_-1^{. Rill morphology is characterized}as“broad and shallow.” (3) In comparison to micro-aspect and micro-slope, the surface roughness associated with different planting patterns exhibited a stronger correlation with rill morphology (P < 0.01). Stepwise regression analysis indicated that surface roughness is the primary factor influencing the width-to-depth ratio of rills, as well as the density and fractal dimension of various planting patterns. The findings of this research can offer a theoretical foundation for the rational allocation of soil and water conservation measures, as well as for the effective prevention and control of soil and water loss in sloping farmland located in alpine canyon regions.
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Spatial Network and Zoning Governance of Carbon Ecological Compensation in Anhui Province Oriented Towards SDGs

ZHANG Xing-hui, ZHANG Kun

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[Objective] Under the dual-carbon goals and sustainable development framework, the development of regional carbon eco-compensation mechanisms plays a pivotal role in reconciling the conflict between economic growth and ecological preservation during land development. [Method] Focusing on Anhui Province, this study establishes an integrated “spatiotemporal differentiation-network connectivity-compensation zoning” framework. Through combined application of network analysis, carbon eco-compensation modeling, entropy weight-TOPSIS method, and K-means algorithm, a differentiated carbon compensation scheme based on Sustainable Development Goals (SDGs) was established. [Result] 1) Significant spatial heterogeneity in net land-use carbon emissions, exhibiting distinct north-south and east-west gradients with higher emissions concentrated in northern and eastern regions during the study period. 2) Emergence of a hierarchical carbon network structure with Hefei as the core node and Wuhu, Ma’anshan, and Huainan as intermediary hubs, demonstrating enhanced network connectivity and core-periphery configuration over time. 3) The spatial difference of carbon compensation value is obvious, the total carbon payment and carbon compensation amount are 109.89×108 yuan and 25.23×108 yuan respectively, and 7 payment zones and 10 compensation zones are identified. 4) Combined with the sustainable development of the city, 7 types of carbon integrated ecological compensation management zones are formed, and the differentiated carbon ecological compensation suggestions of "gradient compensation - collaborative governance" are proposed for each type of area. [Conclusion] The analytical framework and policy recommendations offer critical references for optimizing cross-regional ecological compensation mechanisms and advancing low-carbon spatial governance paradigms. Particularly noteworthy is the novel integration of complex network theory with multidimensional zoning methodology, providing a replicable model for regional carbon management in developing economies.
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Comparative analysis of the differences, enhancement effects, and implications of aggregates in saline-alkali soil versus non-saline-alkali soil

CAIJINGHUI, HUANGLIHUA

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[Objective] Aggregates serve as crucial indicators of soil fertility, and their stability directly influences the physical, chemical, and biological characteristics of the soil. Under salinization and alkalization conditions, aggregates are impacted by the high salinity and strong alkalinity of the soil, which readily give rise to soil structure degradation and functional deterioration, severely constraining agricultural production. [Methods] This article aims to summarize the disparities in aggregates between saline - alkali soil and non - saline - alkali soil, analyze the factors influencing the formation and stability of aggregates under salinization and alkalization circumstances, and explore the methods and strategies for enhancing the aggregate structure in saline - alkali soil, as well as how research on non - saline - alkali soil aggregates can enlighten that of saline - alkali soil. [Results] Comprehensive analysis indicates that the saline - alkali environment undermines the soil structure, reduces microbial diversity and activity, resulting in a decrease in the quantity of large aggregates, an increase in the proportion of micro - aggregates, and poor stability of aggregates. In non - saline - alkali soil, both the number of large aggregates and micro - aggregates are relatively high, with a distinct distribution hierarchy, rich biodiversity, and high stability of aggregates, mainly attributed to the abundant organic matter content and vigorous microbial activities. [Conclusion] To improve the aggregate structure of saline - alkali soil, it is necessary to comprehensively employ hydraulic, physical, chemical, and biological measures to lower the soil salinity and alkalinity content, regulate the pH value, ameliorate the soil structure, enhance the water retention capacity, and increase the nutrient availability. Future research should focus on developing new technical approaches for assessing the aggregate structure, optimizing the improvement techniques, integrating multi - scale data, etc., to facilitate the gradual improvement of the characteristics of saline - alkali soil and the sustainable development of agriculture.
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Study on the spatial variation of soil organic carbon and its control factors in a typical karst county

TU Chun, LUO Weiqun

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[Objective] The karst and non-karst areas in Southwest China are interlaced with strong spatial heterogeneity. Assessing the spatial differentiation and storage of soil organic carbon (SOC) in this region at the county scale is of great significance for achieving regional "dual carbon" goals. [Methods] Taking Wenshan County, a typical karst county in southeast Yunnan Province, as an example, we employed a grid sampling method to conduct the spatial differences in SOC content and storage in top soil(0-20 cm) and deep soil(0-200 cm). Furthermore, we used the semi-variogram function and geographical detector to analyze the impact of external environmental factors on the spatial differentiation of SOC. [Results] The average SOC content in the top soil and deep soil was 17.80 g/kg and 5.18 g/kg respectively, with a total storage of 3770.89×104 t. The distribution pattern revealed higher SOC content in the topsoil of the western region and lower in the central and northern regions, while the deep soil exhibits higher SOC content in the central and western regions and lower in the northeastern region in Wenshan County. In non-karst areas, the SOC content in the topsoil and deep soil was 20.88 g/kg and 6.12 g/kg, respectively, which was 27.94% and 32.75% higher (P<0.01) than in karst areas. The semi-variogram model indicates that the nugget effect value of SOC ranges from 14.62% to 59.93%, indicating that structural factors dominate the spatial differentiation of SOC in Wenshan County. According to the analysis of the geographical detector, temperature and altitude are the main controlling factors affecting SOC in the top soil layer in karst areas. As the temperature decreases and the altitude increases, the SOC content in Wenshan County shows an increasing trend. However, the SOC content in karst areas is generally lower than that in non-karst areas due to their lower altitudes, severe rocky desertification, and relatively poor vegetation growth. For the deep soil, precipitation is the main controlling factor affecting SOC in karst areas. The leaching effect caused by precipitation may combine dissolved calcium with organic matter to form humic acid calcium, promoting the accumulation of SOC in deep soil. In non-karst areas, stratigraphic chronology plays a leading role. The soil developed from Permian basalt parent material may have higher soil clay and macro-aggregate contents, which helps to maintain the physical protection and stability of SOC in deep soil. [Conclusion] This study will provide a reference for the precise assessment of SOC and the regulation of soil carbon pools in the southwestern karst region.
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Soil-microbe-exoenzyme C:N:P Stoichiometric Characteristics in Artificial Pure Forests of Four Tree Species in the Hilly Region of Central Hunan

Lu Qiaolu, FANG Xi

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Abstract: [Objective] The contents of soil carbon (C), nitrogen (N) and phosphorus (P) along with their stoichiometric ratios, were changed due to the varying nutrient uptake and utilization strategies among various tree species plantations, which in turn affected soil microbial activity. However, whether soil microorganisms adapt to these changes by adjusting their biomass and extracellular enzyme stoichiometric ratios remains uncertain. This study aims to explore the effects of various tree species plantation on soil-microbe-exoenzyme C:N:P stoichiometric ratios and to investigate the correlations among soil-microbe-exoenzyme stoichiometry. [Methods] we conducted an investigation into the contents of C, N and P, as well as microbial biomass C (Cmic), N (Nmic), P (Pmic), and the activities of C (β-1,4-glucosidase + β-D-cellosidase, BG + CBH), N (N-acetyl-β-glucosaminidase, NAG), and P (acid phosphatase, ACP) acquiring extracellular enzymes for microorganisms at depths 0-40 cm in four native tree species plantations. These plantations include conifers Pinus massoniana, deciduous broad-leaved Liquidambar formosana, evergreen broad-leaved Schima superba, and Elaeocarpus decipiens, located in the hilly region of central Hunan province and share a common soil development and management history. [Results] (1) Different tree species plantations significantly affected soil C, N, P content, microbial biomass, extracellular enzyme activity, Cmic:Nmic:Pmic and EEAC:N:P. Cmic:Pmic ratios in the P. massoniana plantations and the L. formosana plantations were significantly higher than those in the S. superba plantations and the E. decipiens plantations, indicating that microorganisms compete with plants for soil available P and a low utilization rate of soil P, especially evident in the L. formosana plantation. NAG and EEAN:P in the S. superba plantations were the highest, suggesting that the microorganism was obviously limited by N. ACP in the E. decipiens forest was higher, EEAC:N and EEAC:P were also higher than those in other tree species plantations, while EEAN:P was the lowest, indicating that the microorganisms were most restricted by C and P. (2) There were no significant correlation between soil C:N:P and microbial biomass, extracellular enzyme C:N:P, while only Cmic:Nmic and EEAC:N, Cmic:Pmic and EEAC:P showed significant negative correlation, indicating no covariance between soil C:N:P and microbial biomass C:N:P. There was a significant positive correlation between soil C:N:P and C:Pimb, a significantly negatively correlation between Cmic:Nmic:Pmic and C:N:Pimb, and a significant positive correlation between C:Nimb and EEAC:N, which confirmed the influence of C, N and P differences between soil and microorganisms on the stoichiometric ratio of extracellular enzymes. (3) Existing biomass of litter layer had significant effects on soil C, N, P content, Pmic, Cmic:Pmic, Nmic:Pmic, BG+CBH, NAG, and EEAC:P. [Conclusion] By influencing the contents of soil C, N and P, plantations composed of different tree species modulated microbial biomass and extracellular enzyme activity. Microorganisms can adapt to diverse nutrient limitations by regulating their biomass C:N:P ratios and synthesizing specific extracellular enzymes, thereby substantiating the microbial resource allocation theory.
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Effects of Different Logging Residue Treatments on Acid Hydrolyzed Soil Organic Carbon Fractions and Soil Microbial Communities in a Chinese Fir Plantation

LANG Caifang, GUO Jianfen

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[Objective] Acid hydrolyzed soil organic carbon fractions are important in soil, and their changes of contents will affect soil microbial community composition.To study the response of acid hydrolyzed soil organic carbon fractions and soil microbial communities to different logging residue treatments. [Methods] Three treatments of residue removed (R), residue burnt (RB) and residue retained (RR) were applied to a Chinese fir plantation in the Castanopsis kawakamii Nature Reserve in Sanming Fujian, and soils in different soil layers (0-10 cm, 10-20 cm) were collected three years after planting young Chinese fir to study acid hydrolyzed soil organic carbon fractions (labile fraction Ⅰ, Ⅱ and recalcitrant fraction) and microbial community. [Results] (1) Different logging residue treatments had no significant effect on acid hydrolyzed soil organic carbon fractions in the 0-10 cm soil layer (p>0.05). In the soil layer of 10-20 cm, the content of labile fraction Ⅰ (LP Ⅰ) was significantly higher in the RR (7.2 g·kg-1) and R (6.8 g·kg-1) treatments than in the RB (4.7 g·kg-1) treatment, and the contents of labile fraction II ( LP II, 1.06 g·kg-1) and recalcitrant fraction (RP, 3.59 g·kg-1) in the RB treatment were significantly lower than those in the R treatment (1.32 g·kg-1 and 7.79 g·kg-1, respectively) (p<0.05). The contents of acid hydrolyzed soil organic carbon fractions in the 0-10 cm soil layer of the RB treatment were all significantly higher than those in the 10-20 cm soil layer (p<0.05). (2) The microbial biomass carbon content of the RB treatment in the 0-10 cm soil layer (335.1 mg·g-1) was significantly lower than that of the RR (540 mg·g-1) and R (453.7 mg·g-1) treatments(p<0.05), but there was no significant difference in soil microbial biomass nitrogen in each soil layer between the different treatments (p>0.05). Soil microbial biomass phosphorus content and total PLFAs in two soil layers were significantly higher in RR treatment than in RB treatment (p<0.05). In the 0-10 cm soil layer, the F:B ratio was significantly higher in RB treatment than in RR and R treatments, while GP:GN ratio was significantly higher in RR treatment than in RB and R treatments (p<0.05). (3) There were significant positive correlations between acid hydrolyzed soil organic carbon fractions and total microbial biomass and PLFAs content of each microbial taxon (p<0.05). [Conclusion] Retention of logging residue treatments facilitated the maintenance of different soil organic carbon fractions at high levels and had a positive effect on soil microbial biomass and soil microbial community composition. This study is of great significance for taking reasonable management measures of Chinese fir plantations and improving soil productivity.
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Response Characteristics of Soil Saturated Hydraulic Conductivity after returning orchard to farmland in Loess Plateau

LI Shuyi, QIAO Jiangbo

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[Objective] As the largest apple producing area in China, the Loess Plateau has faced the problems of aging apple trees and simplification of varieties in recent years. In addition, in order to ensure national food security, many orchards in the Loess Plateau have been converted into farmland. In order to explore the change rule and influencing factors of soil saturated hydraulic conductivity ( Ks ) after returning orchard to farmland. [Methods] In this study, mature apple orchards ( AO ) and orchards with different tillage years ( 2a, 4a, 6a, 10a ) in the Loess Plateau were selected as the research objects, and the original farmland ( CK ) was used as the control. The Ks and soil basic properties of 0-200 cm in different plots were measured. Pearson correlation analysis and structural equation model were used to analyze the response characteristics and influencing factors of Ks after returning orchard to farmland in the Loess Plateau. [Results] With the increase of returning years, the average soil water content, clay and silt content in 0-200 cm of farmland showed a decreasing trend. The average sand content showed an increasing trend. The order of Ks mean values in different plots is 2.25±1.19 cm/h(6a)＞1.60±0.71 cm/h(AO)＞1.49±0.29 cm/h(4a)＞1.46±0.44 cm/h(2a)＞1.40±0.40 cm/h(CK)＞1.04±0.61 cm/h(10a). On the whole, with the increase of returning years, the average value of Ks increased first and then decreased. With the increase of soil depth, Ks in different plots showed a decreasing trend. The direct influencing factors of Ks were soil bulk density and organic matter content, and the indirect influencing factors were tillage years and soil depth. [Conclusion] The research results can provide theoretical support for the response law of soil water movement to land use change in loess tableland area, and provide scientific basis for promoting the prevention and control of soil erosion and the rational use of land in this area.
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Influence Mechanism of Carbon transport and sequestration with carbon source addition in purple soil slope farmland under Natural Rainfall

LIU Bing, HAO Zhuo

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[Objective]Degradation of purple soil is critical, water loss is serious, and it is difficult to increase and sequester carbon in the soil. In order to explore the impact of carbon source addition on the carbon sequestration of purple soil farmland。[Methods]Purple soil slope cropland in Sichuan Province was selected as the study. Six treatments were set up on 10° purple soil slopes: no fertilization (CK), fertilizer + straw returning (T1), fertilizer + straw biochar (T2), fertilizer + cow dung (T3), fertilizer + organic soil matrix (T4), fertilizer + biochar cow dung and mushroom slag compost (T5), each treatment was repeated 3 times. Analyze the change characteristics of runoff, sediment and carbon content under rainfall and different carbon sources.[Results]The results showed that (1) rainfall over 30 mm and short-term heavy rainfall (16.1 mm·h-1) could lead to surface runoff. The addition of carbon sources notably decreased surface runoff. In comparison with the CK , the flow reduction benefits of T2, T3, and T5 reached 38.64%, 38.61%, and 62.95%, respectively. The sediment erosion in different treatments was observed to follow the order: T1>T4>CK>T2>T3>T5, with the highest reduction of 58.99% compared to the CK . (2) The loss of organic carbon through surface runoff was primarily attributed to sediment organic carbon, which accounted for 67.47~90.43% of the total organic carbon loss. Treatments T2, T3, and T5 were effective in reducing the migration of organic carbon, resulting in a total organic carbon loss reduction of 21.74%, 19.40%, and 49.28%, respectively, compared to the CK treatment. Furthermore, the carbon fractions of T5 treatment, including dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), dissolved total carbon (DTC), and sediment organic carbon, exhibited a reduction in migration fluxes by 70.88%, 70.92%, 37.52%, and 60.07%, respectively, compared to the CK treatment. (3) PLS-PM showed that the C sequestration of soil organic carbon was influenced to varying degrees by rainfall characteristics, soil physicochemical properties, and the addition of different carbon sources.[Conclusion]Carbon sources (T2, T3, T5) reduces the total amount of organic carbon loss. T5 processing organic carbon sequestration stock increases, T2 and T3 reduce the loss of each carbon component of surface runoff, while its organic carbon sequestration stock decreases. It shows that the addition of carbon source can increase the carbon content and reduce the carbon migration, but that the solid stock is reduced, which needs to be verified by long-term experiments. This study holds significant importance in enhancing the fertility of purple soil, maintaining soil carbon balance, and reducing soil carbon loss.
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A new method to estimate the cover management factor on the Loess Plateau in China: A case study using millet field.

Xie Xnli, Wu Faqi

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[Objective]The●present●study●attempted●to●investigate●the●combined●effect●of●crop●cover●and●crop●management●practices●on●preventing●soil●loss●and●improving●the●accuracy●of●C-factor estimation.[Methods]●Six●millet●plots●with●different●treatments,（i.e.,●crop●plot●(C1),●crop-roughness●plot●(C2),●crop-crust●plot●(C3),●bare●plot●(B1),●roughness●plot●(B2),●crust●plot(B3))●were●established●and●the●soil●loss●at●four●growth●stage●was●determined●by●simulated●rainfall.●The●C●factor●was●calculated●using●soil●loss●ratio●(SLR).●The●major●factors●affecting●SLR●were●also●analyzed●and●their●correlations●with●SLR●were●then●regressed●through●numerical●simulation●using●MATLAB.●Subsequently●the●SLR●estimation●models●designed●for●soil●erosion●prediction●on●the●Loess●Plateau●could●be●built.●Finally,●the●C●factor●could●be●calculated●using●the●proposed●SLR●estimation●model●combined●with●the●distribution●curve●of●rainfall●erosivity.[Results]●Surface●roughness●and●soil●crust●can●reduce●soil●loss●in●crop●plot.●Compared●with●,●the●mean●decreasing●of●●and●●was●21%,●16.5%,●respectively.●The●model●formulas●of●crop●plot,●crop-roughness●plot,●crop-crust●plot●were●obtained,●through●validating●by●field●soil●and●water●loss●data●conducted●at●Chunhua●county,●the●model●formulas●can●achieve●accurate●prediction,●the●estimated●C●values●for●the●whole●growth●stage●were●0.30,●0.25,●0.25,●respectively,●with●the●Nash●coefficients●were●0.96,●0.87,●0.75,●respectively.[Conclusion]●These●results●could●provide●some●insights●for●estimating●C●values●at●national●scales.
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The Applicability Evaluation of Multisource Precipitation Data for Runoff Simulation in a Typical Basin on the Tianshan Mountains

WANG Wenyu, WANG Xiaoyan

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[Objective] In order to explore the difference of precipitation characteristics for multisource precipitation products and their applicability for runoff simulation in an alpine basin on the Tianshan Mountains. [Methods] A comparative analysis of the spatiotemporal characteristics of precipitation is conducted in the upper reaches of the Manas River Basin, based on the datasets CN05.1, GPM, AIMERG, CMFD, and ERA5. Subsequently the accuracy of different products is evaluated based on observed precipitation, and their applicability for runoff simulation is assessed by means of HBV hydrological model. [Results] The spatial pattern for all the precipitation products is characterized by the increase and then decrease from the north to south, whereas only AIMERG and CMFD are able to display higher precipitation in the glacier area. Consistent seasonal variation are detected, but large difference in summer precipitation are shown. At summer, ERA5 is twice as much as CN05.1, and GPM is lower than the other precipitation products. GPM underestimates the monthly precipitation, especially in winter and spring (64%～76%). While the monthly precipitation is overestimated by CMFD, ERA5 and AIMERG. The overestimation of ERA5 is the most serious, especially in summer and autumn (134%～206%), and CMFD slightly overestimates the monthly precipitation. AIMERG has the higher correlation with the observed monthly precipitation and greater critical success index in both rainy season and the non- rainy season. AIMERG, CMFD and CN05.1 have the greatest ability to reproduce daily runoff, with the higher NSE (0.81～0.82) and lower relative error (＜6%). Moreover, the former two products show higher performance in reproducing extreme runoff when compared with CN05.1.[Conclusion] AIMERG and CMFD show great potential in runoff simulation of the upper Manas River. The results can serve as data references for runoff simulation and soil erosion prevention research in the Tianshan region, where meteorological data is limited.
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Transpiration characteristics of common trees and their response to meteorological factors in Karst slope secondary forest

guiyuxiang, pengtao

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[Objective] To explore the transpiration characteristics of common trees and their response to meteorological factors in karst slope secondary forest. [Methods] Heat diffusion probe method (TDP) was used to monitor Broussonetia papyrifera, Koelreuteria paniculata, Triadica sebifera, Ailanthus altissima, Melia azedarach, Toona sinensis, and Rhus chinensis in Puding Karst Ecosystem Observation and Research Station of Chinese Academy of Sciences, and to study the relationship between tree transpiration characteristics and meteorological factors. [Results] (1) The average daily transpiration of Broussonetia papyrifera, Koelreuteria paniculata, Triadica sebifera, Ailanthus altissima, Melia azedarach, Toona sinensis, and Rhus chinensis were: (4 409.97±3 260.63) g/d, (6 611.27±5 629.57) g/d (3 956.32±2498.50) g/d (2984.98±2039.09) g/d (6 300.25±4 637.71) g/d, (780.69±738.80) g/d, (2320.73)±1717.18) g/d.(2) The fluid flow rates of Broussonetia papyrifera, Koelreuteria paniculata, Triadica sebifera, Ailanthus altissima, Melia azedarach, Toona sinensis, and Rhus chinensis were the highest in sunny days, followed by cloudy days, and the lowest in rainy days. (3) The influence of atmospheric temperature (T) and saturation water vapor pressure difference (VPD) on Broussonetia papyrifera, Koelreuteria paniculata, Triadica sebifera, Ailanthus altissima, Melia azedarach, Toona sinensis, and Rhus chinensis under sunny weather was the greatest, followed by relative humidity (RH) and total irradiance (Eg). [Conclusion] The transpiration of common trees in secondary forest of karst slope is limited by special water environment. Different deciduous trees have different water use strategies, and the liquid flow rate is mainly affected by VPD and Eg.
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Analysis of the Dynamic Relationship between Runoff and Phosphorus Transport in the Menglianggu Small Watershed

yangcailing, Yu Xingxiu

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[Objective] To investigate the characteristics of runoff-phosphorus loss hysteresis relationship under different rainfall types. [Methods] This study focused on the Menglianggu small watershed in the rocky mountainous area of northern China. Using data from 32 rainfall events recorded between 2010 and 2012, C-Q (concentration-discharge) loops and Pearson correlation analysis were applied. [Results] (1) During torrential rain, a large amount of phosphorus was released after soil saturation, causing the phosphorus concentration peak to lag behind the runoff peak. In the case of heavy rain, dissolved phosphorus was released from nearby sources, while particulate phosphorus was transported from distant sources to the runoff. During moderate rain, the transport of DIP (dissolved inorganic phosphorus), PP (particulate phosphorus), and TP (total phosphorus) was mainly influenced by surface runoff, whereas DP (dissolved phosphorus) was affected by soil and sediment. Light rain showed rapid transport of dissolved phosphorus and slower transport of particulate phosphorus. (2) The C-Q loops of phosphorus transfer exhibited various patterns during the runoff process. PP and TP often showed a clockwise lag, accounting for 18%~23%, mainly due to the strong scouring of surface runoff. The counterclockwise lag appeared in 12%~18% of the phosphorus components, resulting from the slow release of soil phosphorus and the resuspension of riverbed sediments. DP loss mainly exhibited a figure-eight positive loop, accounting for 16%, while DIP loss showed a figure-eight negative loop, accounting for 19%. Linear lags were less frequent, and complex lags ranged between 31% and 45%. (3) Under torrential and heavy rain conditions, DIP and DP had weak or negative correlations with runoff (Q), attributed to the rapid surface scouring, which caused particulate phosphorus to be more easily lost, while dissolved phosphorus was adsorbed by the soil or diluted by the runoff. In moderate rain, the appropriate runoff scouring force enhanced the releases of dissolved phosphorus. In light rain, runoff primarily transported particulate phosphorus attached to loose soil particles. PP and TP were consistently highly correlated across different rainfall types, indicating that TP mainly originates from PP. [Conclusion] The Menglianggu watershed needs to be protected against phosphorus loss for different rainfall conditions.
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Characteristics and drivers of spatial and temporal soil erosion in Anshun City, Karst region

Wenxian Wu, Yuan Li

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[Objective] To explore the spatial and temporal evolution of soil erosion, driving factors and the interaction between driving factors in Anshun City, a karst area in southwest China, which can help the management of rock desertification and soil and water resources in the area. [Methods] The optimised RUSLE model was used to estimate soil erosion in Anshun City from 2005 to 2020, while the Random Forest Model (RF) was used to reveal the driving factors of soil erosion, and to estimate the effects of driving factor interactions on soil erosion in Anshun City from 2005 to 2020. [Results] (1) from 2005 to 2020, soil erosion in Anshun City generally shows that low-intensity soil erosion is distributed in the central, southeastern and eastern regions, while high-intensity soil erosion is distributed in the northern and southwestern regions. From the time point of view, soil erosion in Anshun City as a whole shows a trend of improvement, most of the areas of soil erosion grade mainly from high to micro-intensity erosion transfer, but there are local areas of erosion exacerbation phenomenon. (2) Rocky desertification has a greater impact on soil erosion in Anshun. The soil erosion intensity of Anshun is positively correlated with rocky desertification in the area accounting for 59.3% of the total area, which is highly correlated. Soil erosion with the increase of rocky desertification intensity shows the trend of increasing and then decreasing. (3) The most important land use types in Anshun City where soil erosion occurs are forest land, arable land and grassland, and the overall rate of soil erosion is in the order of forest land < grassland < arable land. (4) The analysis of the driving factors of soil erosion showed that the vegetation cover and management factor had the strongest explanatory power for the spatial and temporal dynamics of soil erosion in the study area, followed by the factor of soil and water conservation measures and the intensity of rock desertification. The results of driver interaction showed that the interaction between vegetation cover and management factor and soil and water conservation measures factor was the dominant factor, and the top ranked interactions all had the participation of vegetation cover and management factor. [Conclusion] Soil erosion intensity in Anshun City showed an overall trend of improvement from 2005 to 2020, but there was an increase in erosion in some areas. Vegetation cover, rock desertification intensity and land use have the strongest influence on soil erosion in Anshun City. Therefore, the future soil and water management process needs to focus on vegetation cover, rock desertification intensity and land use changes.
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Morphological Characteristics and Spatial Evolution Laws of rural settlements at Peak-cruster Depressions in Rocky Desertification Areas

LIN Guang, WANG Yan

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[Objective]In order to explore the morphological characteristics and spatial evolution patterns of rural settlements in the rocky desertification area of the Peak Tree Depression, it is of great significance for the optimisation of the spatial layout of the rural settlements and the promotion of the urban-rural integration and sustainable development.[Methods] Based on the PLUS model, we predicted the distribution of rural settlements under the economic development scenario, natural development scenario and ecological protection scenario in 2035, identified the morphological features of rural settlements using the morphological spatial analysis (MSPA) method, and adopted the landscape pattern index, landscape integrated dynamic attitude and Ripley"s K-function method to realise the analysis of the morphological features and spatial evolution patterns of rural settlements in the past-now-future. The morphological characteristics and spatial evolution patterns of rural settlements in the past, present and future were analysed. [Results] (1) The area of rural settlements showed an upward trend from 1990 to 2022, with an increase of 6.09km_² in area and an increase in the number from 366 to 1253. The core and the edge are the dominant rural settlement types in the study area, with an increase in their areas of 1.90km₂^{and 1.51km}_² respectively, which are mainly located in the central part of the study area, and the islands and branches are mainly located in the northern and northeastern parts of the study area. distributed in the northern and north-eastern parts of the study area and their areas increased by 1.07km₂^{and 1.15km}_² respectively.(2) The complexity, richness and fragmentation of rural settlement types show an overall increasing trend; the development of rural settlement types is the most gentle in 1990-2000, and the development is the most drastic in 2010-2022, and the expansion of rural settlement types mainly occurs in Xingjie and Laojie villages and the surrounding areas; rural settlement types show a tendency of agglomeration in the study scale. The rural settlement types show a tendency of agglomeration in the study scale, and with the increase of the spatial scale, the aggregation characteristics of the spatial distribution of rural settlements are weakened and the spatial scale of the urbanisation process is narrowed.(3) Under all three scenarios, the area of rural settlements shows an upward trend, and its area is 11.42km₂^{, 7.68km}₂^{and 9.14km}_² respectively; the core is the absolutely dominant type in the study area, and its area increases by 4.02km₂^{, 2.60km}₂^{and 3.14km}_² respectively, and the types of rural settlements show a clustered distribution on the spatial scale, and the ecological protection scenario will inhibit the rural The ecological protection scenario will inhibit the expansion of rural settlements.[Conclusion] Rural settlements in the study area are in the stage of rapid development, and the expansion of rural settlements is mainly manifested in the core expansion, while the expansion of isolated islands is exacerbating the complexity of the spatial distribution of rural settlements, and the process of urbanisation has gradually aggregated rural settlements in a smaller spatial scale.
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Liu Ping an, Hu Xiaomin ,Chen Siyu, Tian Ye, Ma Yutong, Luo Xinyu, Zhuang Zhuo rui，Zhang Min, Zhang Wenrui, Feng Zhibang, Li Zeli, Chen Qi*, Zhang Min*, Liu Zhiguang

liu ping an, chen qi

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[Purpose] Controlled release potassium chloride can achieve slow release of potassium ions synchronized with crop absorption, while ensuring the effectiveness of potassium ions in the soil, meeting the potassium demand of crops in the later stages of growth, and significantly improving potassium fertilizer utilization efficiency. Exploring the effects of long-term application of controlled release potassium chloride and its mixed fertilizers on maize yield and quality, providing technical support for achieving high-quality maize production. [Method] A field long-term positioning experiment based on the application of controlled release potassium chloride to summer maize (Zea mays L., Zhengdan 958) was conducted (starting from 2014). Six treatments were set up, including no potassium fertilizer (CK), constant ordinary potassium chloride (K), controlled-release potassium chloride (CRK1), reduced potassium amount by 1/3 polyurethane coated potassium chloride (CRK2), constant mixed potassium chloride (BBF1), and reduced potassium amount by 1/3 mixed potassium chloride (BBF2). Relevant indicators such as maize growth, soil potassium supply level, potassium absorption capacity, and photosynthesis were calibrated during the tasseling period, and corn quality and agronomic benefits were measured during the mature period. Measurement. [Results] (1) The corn yield, aboveground biomass, and economic benefits of BBF1 treatment were the highest, at 12157 kg/hm2, 19954 kg/hm2, and 19183 yuan/hm2, respectively. Under equal potassium conditions, compared with other potassium application treatments, they significantly increased by 5.68% to 16.06%, 1.11% to 10.44%, and 10.39% to 28.37%, respectively. Compared with BBF1 treatment, BBF2 significantly increased potassium fertilizer utilization by 9.44%. (2) The potassium ion content in CRK1 and BBF1 was significantly increased by 19.93% and 13.89% compared to K, and significantly increased by 16.05% and 19.03% compared to CRK2 and BBF2, respectively. After reducing by one-third, CRK2 and BBF2 were not significantly higher than K. CRK1 significantly increased SPAD value by 7.32%, LAI value by 7.04%, and net photosynthetic rate by 18.58% compared to K. After reducing by one-third, CRK2 was not significantly higher than CRK1 and K. (3) Compared with K treatment, CRK1 treatment increased the crude protein, starch, and oil content of corn kernels by 4.23%, 4.46%, and 5.65%, respectively; After reducing potassium by one-third, CRK2 still increased the crude protein, starch, and oil content of corn kernels compared to K treatment. The mixed application of controlled release potassium chloride and ordinary potassium chloride (BBF1) further increased the crude protein, starch, and oil content per unit area of corn kernels compared to K treatment, but the difference was not significant compared to CRK1 treatment; After reducing potassium by one-third, there was no significant difference in starch and oil content per unit area of corn kernels between BBF2 treatment and CRK1 and BBF1 treatment. [Conclusion] Controlled release potassium chloride can meet the potassium requirements for maize growth and quality formation, improve maize growth, optimize the quality traits of maize grains, significantly increase maize yield and potassium fertilizer utilization efficiency, reduce fertilizer input costs, and achieve the goal of reducing yield without reducing yield and quality.
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Spatial-temporal patterns and factors of soil moisture in the Middle Yellow River under changing environments

Liu Bo, Peng Shouzhang

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[Objective] To identify the main driving factors of soil moisture in the middle reaches of the Yellow River, to analyze the impact of land cover and climate change on soil moisture changes in the middle reaches of the Yellow River, and to provide a theoretical basis for regional ecological environmental protection and high-quality development. [Methods] The SiB2 model was used to simulate the surface soil moisture (SSM) and root zone soil moisture (RZSM) in the middle reaches of the Yellow River for the years 2000, 2005, 2010, 2015 and 2020, and to analyze their spatial and temporal distribution patterns; the main driving factors were analyzed by combining the GeoDetector, Random Forest, and SHAP; and the contribution of land cover and climate change to the changes of SSM and RZSM was analyzed by using scenario-setting method. [Results] (1) The SiB2 model can better simulate the soil moisture in the middle reaches of the Yellow River after the parameter calibration. (2) Soil moisture in the middle reaches of the Yellow River showed overall spatial distribution characteristics of high in the south and low in the north, and there were differences in the distribution characteristics of SSM and RZSM under different ecological zones, different seasons and different land cover types. (3) Precipitation, soil type and downward shortwave radiation are the main drivers of SSM in the middle reaches of the Yellow River, and precipitation, soil type and land cover type are the main drivers of RZSM in the middle reaches of the Yellow River, and there are differences in the drivers of soil moisture in different ecological zones. (4) The effect of land cover type conversion on RZSM in the middle reaches of the Yellow River is regionally different, and the main direction of change is the decrease of RZSM due to the increase of LAI. (5) Compared to 2000, the decline in SSM and RZSM in 2020 is dominated by differences in climate change and land cover change, respectively. [Conclusion] Land cover changes in the middle reaches of the Yellow River from 2000 to 2020 led to a decline in soil moisture in the root zone, and precipitation magnitude had an important effect on changes in soil moisture after land cover type conversion.
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Study on spatial and temporal changes of vegetation cover and its driving factors in Panzhihua City, 1990-2020

Li Jianhui, 何淑勤

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[Objective] To investigate the spatial and temporal variation characteristics and driving factors of vegetation cover in Panzhihua City, and to provide theoretical basis for Panzhihua City to formulate regional ecological environmental protection programs and maintain regional ecological balance. [Methods] Based on Landsat-EVI data, combined with natural and socio-economic data, we analyzed the characteristics and driving factors of vegetation cover in Panzhihua City during the period of 1990-2020 with the help of like element dichotomous model, Sen+MK trend, partial correlation and optimal parameter geographic detector model. [Results] (1) The spatial distribution of vegetation cover (FVC) in Panzhihua City was characterized by “low in the south and high in the north”, with high-grade vegetation cover dominating. In the past 30a, the FVC ranged from 0.635-0.792, with the area of degraded area accounting for 17.70% and the area of improved area accounting for 44.97%. (2) The area proportion of areas where FVC was positively correlated with precipitation and air temperature is 61.87% and 57.40%, respectively. (3) Land use, elevation, and air temperature are the main influencing factors of spatial differentiation of FVC, with the influence above 0.2; most of the interactions among the factors were shown to be enhanced, among which, the influence can be increased to 43% after the coupling of slope direction and air temperature; the influences of the driving factors on the growth of vegetation in the study area have their appropriate ranges. [Conclusions] In the past 30a, FVC showed an overall upward trend, but the vegetation degradation is obvious in some areas. In the future, regional vegetation construction needs to focus on the terrain distribution pattern and climate change when optimizing the land-use pattern, in order to cope with the challenges of sustainable development of vegetation ecosystems under environmental evolution.
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Characteristics of Soil Saturated Hydraulic Conductivity and Its Influencing Factors at Different Landscape Positions in a Small Peak-Cluster Depression Watershed of Karst Region

YU Xinrui, LI Xuezhang

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[Objective] Peak-cluster depression is one of the important karst landform types. Exploring the influence of different landscape positions on soil saturated hydraulic conductivity (Ks) can provide a reference for further understanding of the hydrological processes in this area. [Methods] Ks and the corresponding soil physical and chemical properties of different soil depths in slope and depression were measured. By measuring Ks and soil physical and chemical properties of different soil depths in slope and depression, the distribution characteristics of Ks and the corresponding influencing factors were studied according to variance analysis, regression analysis and path analysis. [Results] Landscape position and soil depth had significant influence on Ks distribution (p<0.05). The influence of landscape position was mainly identified at 0—10 and 20—30 cm soil depths, and the influence of soil depth was primarily occurred in the slope. The effect of land use on Ks was not significant (p>0.05). The influence of landscape position on soil particle composition and total phosphorus was not obvious (p>0.05), but organic carbon, total nitrogen and bulk density changed significantly with landscape position (p<0.05). Ks of slope location was significantly positively correlated with silt, sand, organic carbon and total phosphorus (p<0.05), and significantly negatively correlated with clay and bulk density (p<0.05). There was a significant positive correlation between Ks of depression location and bulk density (p<0.05). Path analysis indicated that bulk density and organic carbon were the primary factors affecting Ks in both slope and depression. The regression equations of Ks in slope and depression were established based on multiple stepwise regression, and the variance explanation rates of influencing factors were 76.2% and 32.6%, respectively. [Conclusion] The results showed that the difference in geomorphic features had a major impact on the distribution of soil hydrological parameters. It can provide a scientific basis for the study of soil and water processes in small peak-cluster depression watershed of karst region.
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Effect of hydropower station on vegetation temporal and spatial change in the middle reaches of Jinsha River

ZHANG Jiazheng, ZHU Daming

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[Objective] To explore the effects of hydropower stations on the temporal and spatial changes of vegetation, clarify the response relationship of vegetation changes to hydropower station construction and climate factors, and provide a reliable scientific basis for regional sustainable development and sustainable operation of hydropower stations. [Methods] In this paper, the normalized vegetation index (NDVI) was used to reflect vegetation change. Google Earth Engine (GEE) was used as the computing platform, coupled with ModTrendr algorithm, Theil Sen-MK, contribution degree analysis and partial correlation analysis methods to explore the effects of hydropower stations in the middle reaches of the Jinsha River on the spatial-temporal changes of vegetation during 2000-2022. And analyze the effect of climate in it. [Results] (1) The negative mutations were concentrated from 2011 to 2014, and the mutation area was concentrated in the catchment area. The forward mutation was concentrated in 2015 and 2017, and the mutation area was concentrated within the 5-km buffer zone of the riverbank. The time for vegetation to produce positive response was 1-4 years after impounded water, and the mutation intensity gradually weakened along the riverbank. (2) The vegetation NDVI around each hydropower station presents an overall upward trend (0.0002-0.0028/a), and an upward (gentle) -- downward -- upward trend before, during and after construction; (3) The regional vegetation change is mainly caused by the joint action of human activities (hydropower station construction) and climate change, and the explanation degree is 69.12%. The contribution of human activities is much higher than the contribution of climate change. (4) The partial correlation coefficients of temperature, precipitation and NDVI are -0.28 and -0.29, respectively. The partial correlation coefficients of temperature and precipitation differ greatly in different stages of hydropower station, indicating that hydropower station will affect regional climate. [Conclusion] Hydropower station has a negative impact on vegetation during construction and a positive impact on vegetation after operation. The impact of hydropower station construction on vegetation is higher than that of climate change, and the construction of hydropower station may affect local climate, and the overall correlation between temperature and precipitation and vegetation NDVI decreases.
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Response of Soil Moisture to Typical Rainfall at Different Stands and Slope Sites in Qiaoshan Forest Region

Guo Yixuan, LI Jing

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[Objective]Rainfall is the main source of soil water supply, which directly affects the distribution characteristics of soil water, and then affects the growth of vegetation. [Methods]This study took the Qiaoshan forest area in the southern Loess Plateau as the research object. Through monitoring the rainfall and soil moisture at different depths of typical stands (broadleaf pure forest and mixed forest), the response characteristics of soil moisture at different layers to rainfall patterns under different vegetation cover and slope location conditions were explored. [Results](1) Rainfall during the study period was mainly concentrated in August, September and October, with the highest rainfall of 251.7mm in September. The seasonal difference of soil moisture in the same soil layer at different points was significant (p≤0.05), and the average soil moisture in different soil layers was the lowest in summer. (2) During moderate rainfall events, only shallow soil moisture content responded to rainfall, and the response intensity of soil moisture content to rainfall in mixed forest was greater than that in broad-leaved pure forest. (3) In the event of heavy rain, the response of soil moisture to rainfall was greater in the mixed forest than in the pure broad-leaved forest, and the response relationship was as follows: the shallow layer was lower slope > middle slope > upper slope, and the deep layer was upper slope > middle slope > lower slope. (4) In the event of heavy rainfall, the response of soil moisture to rainfall was greater in broad-leaved pure forest than in mixed broad-leaved forest, and the response relationship was as follows: in shallow layer, it was lower slope > middle slope > upper slope, and in deep layer, it was upper slope > middle slope > lower slope. (5) In the three rainfallings, the supplement amount of the mixed forest was 1.087, 1.653 and 1.004 times that of the pure broad-leaved forest, respectively. [Conclusion]It is of great significance to study the response of soil moisture to rainfall and the process of shallow soil moisture movement in Qiaoshan forest area for optimal allocation of rainfall resources and sustainable restoration of forest ecosystem.
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Study on Urban Landscape Ecological Risk Measurement and Influencing Factors in the Yellow River Delta

Li Jianchun, Yuan Wenhua

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[Objective]The Yellow River Delta, a typical ecological fragile area, faces prominent landscape ecological risk (LER) due to multiple factors. Systematic understanding of landscape risk is crucial for optimizing landscape patterns and effectively addressing ecological challenges.[Methods] Taking Dongying, a typical city of the Yellow River Delta as the study area to construct a assessment framework of ecosystem service value and the probability of landscape ecological damage in terms of “stress-vulnerability-resilience”. The ESDA and Geographic detector were used to explore the spatial heterogeneity and influencing factors of LER at the grid scale.[Results](1) The average value of LER in Dongying is 0.15, generally shows a spatial pattern of “high in the north and east, low in the middle and southwest”. The total value of ecosystem services is about 3 175.99 billion yuan (93% of GDP), indicate unsustainable economic growth, showing a pattern of gradual diminution form the north and eastern coast to the southwestern. The probability of ecological damage is 0.43, showing a pattern of “staggered distribution of high and low in the north and east, and overall low in the southwest part”.(2) It is found that the LER showed significant clustering in spatial distribution, with a global Moran’s I index of 0.747. In terms of agglomeration zoning, the HH risk agglomeration area accounts for 32.48% of the area of the risk zone, which is mainly distributed in the continuous distribution zone formed by the coastal zone in the north and east of Dongying.(3) The LER of Dongying is mainly dominated by factors of socio-economic foundation and environmental location conditions. In the citywide area, the determinant of coastline distance was 0.43, which was the primary factor dominating the urban LER. In contrast, in the urban area, the determinant of population density was 0.38, which was the decisive factor influencing the urban LER.[Conclusions] This study enriches the LER assessment method theoretically, and provides empirical support for ecological protection and risk management in the Yellow River Delta.
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Effects of organic fertilizer substitution and aggregation on microfauna communities in red soils

ZHU Junkang, LIN Yongxin

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[Objective] Red soil is a typical soil in southern China, and organic substitution is an important way to improve the physicochemical properties of red soil. This study aims to explore the effects of different organic substitution materials and aggregation on the microfauna communities in red soil. [Methods] In this study, five long-term fertilization treatments were collected: application of inorganic nitrogen, phosphorus, and potassium (NPK) fertilizer alone (I), NPK + peanut straw (IPS), NPK + rice straw (IRS), NPK + radish (IR), and NPK + pig manure (IPM). Soil aggregates were fractionated, and high-throughput sequencing was used to determine the microfauna communities within the aggregates. [Results] Compared to I, IPM and IRS significantly increased soil organic matter content, while IPS and IR had relatively smaller effects. IPM also significantly increased soil pH, total nitrogen, and available phosphorus content. Organic substitution had no significant effect on the diversity of soil microfauna but significantly influenced their community structure. Nematodes were the most abundant soil microfauna in upland red soil, with a relative abundance of 93.0% in I. IPM and IRS significantly reduced their relative abundance to 62.2% and 70.0%, respectively, while IPS and IR had smaller effects. Aggregate size significantly affected the Shannon and Chao1 indices of soil microfauna, with the diversity indices of 53-250 μm and <53 μm aggregates significantly higher than those of 250-2000 μm and >2000 μm aggregates, indicating that smaller particle sizes are more conducive to increasing soil microfauna diversity. Aggregate size also significantly affected soil microfauna community structure, but its impact was weaker than that of organic substitution. [Conclusion] Both organic substitution and aggregate size could significantly affect soil microfauna communities, with pig manure and rice straw having greater effects than peanut straw and radish. The aggregation process reduced microfauna diversity in red soils.
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Extracellular Enzyme Stoichiometric Characteristics of Subtropical Forest Soil under Forest Fire Disturbance

GUO Qiling, WANG Jianqing

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Forest fire, as the main natural and human disturbance process of subtropical forest ecosystem, seriously affects the soil biochemical cycle. However, the response of soil extracellular enzyme activities to the restoration process after forest fire disturbance is still unclear. In this study, the soils of subtropical secondary forests at different restoration stages after forest fire disturbance were selected as the research object, and the subtropical forest soils in seven restoration stages of secondary forest were selected by using the method of spatial substitution time series, and the soil was divided into old forest (60-70 years), middle-aged forest (30-40 years) and young forest (<20 years). Through the determination of soil carbon (C), nitrogen (N), phosphorus (P) related invertase activities, to reveal the forest fire disturbance of subtropical forest soil extracellular enzyme activity and its stoichiometric characteristics succession rule. The results showed that the activities of soil cellulose hydrolase (CBH) and β-N-acetylglucosaminidase (NAG) increased significantly with the time of succession, while the activities of other enzymes did not change significantly. The results of correlation analysis and redundancy analysis showed that soil C and N contents were the key factors affecting the change of soil extracellular enzyme activity. In addition, the ratios of soil extracellular enzyme C, N and P in young, middle and old forests were 1:0.94:1.53, 1:1.02:1.63 and 1:0.99:1.47, respectively, indicating that the growth of forest soil microorganisms in subtropical areas was limited by P, and improves gradually with the increase of restoration years after forest fire disturbance. In summary, after forest fire disturbance, the extracellular enzyme activity of forest soil showed an increasing trend with the restoration time, and the stoichiometric characteristics of soil extracellular enzyme gradually tended to be stable, indicating that soil health status of subtropical forest was gradually improved with the restoration process of forest fire disturbance.
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Spatial and Temporal Correlation Analysis and Prediction of Land Use Ecological Risk and Carbon Stock in Yunnan Province

XU Rui, ZHU Daming

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[Objective]To explore the correlation between land use ecological risk and carbon storage, in order to improve the regional ecological risk prevention and carbon sequestration capabilities, so as to effectively guide the formulation of environmental management policies.[Methods] The landscape pattern index, PLUS and InVEST models were used to analyze and predict the spatial and temporal changes of land use ecological risk and carbon storage in Yunnan Province under scenarios of natural development, economic development, and ecological protection. Spearman correlation analysis and spatial autocorrelation analysis were used to explore the correlation characteristics.[Results] (1) Land use in Yunnan Province is dominated by forest land, exceeding 57% of the total area.(2) From 2000 to 2020, the ecological risk in Yunnan Province decreased slowly, with lower and medium-risk areas exceeding 50%, the spatial distribution remained relatively stable, the change of risk mainly occurred between adjacent levels, and the high-level risk area transferred to the low-level risk area by 39 675.06 km2.(3) Carbon storage in Yunnan Province initially increased and then decreased, with a total reduction of 2.257×107 t over 20 years. Forest land contributed the most to carbon storage, while large-scale conversion of cropland, grassland, and forest land into construction land was the main reason for the reduction in carbon storage.(4) The ecological risk and carbon storage of Yunnan Province will decrease under all three scenarios in 2030. Under the ecological protection scenario, forest land area increased by 895.83 km2 compared to 2020, high and higher ecological risks significantly decreased, and the reduction in carbon storage was suppressed, indicating that this is the optimal scenario for the future development of Yunnan Province.(5) Ecological risk and carbon storage in the study area are negatively correlated, with spatial distribution mainly characterized by low-high and high-low aggregations.[Conclusion] The study provides various recommendations based on the spatial aggregation characteristics of ecological risk and carbon storage in Yunnan Province, offering a scientific basis for preventing ecological risks and enhancing carbon storage in the region.
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Effects of Water and Nitrogen Management on Soil Nitrogen Metabolism Enzyme Activity and Wheat Nitrogen Utilization

CUI Zhenkun, SHI Yu

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[Objective] To explore the effects of water and nitrogen management on soil nitrogen metabolism enzyme activity and wheat nitrogen utilization under irrigation based on soil moisture. [Methods] The experiment adopted a two-factor split zone design, and the main plot was three irrigation levels: the relative water content of 0-40 cm soil layer at jointing and anthesis stages of wheat was supplemented to 65% (W1), 75% (W2) and 85% (W3). Four nitrogen application rates were applied as the subplot: pure nitrogen 0 (N0), 150 (N1), 180 (N2) and 210 (N3) kg/hm2. Soil nitrogen metabolism enzyme activity, nitrogen accumulation and translocation, nitrogen nutrition index (NNI), residual amount of nitrate nitrogen, grain yield, water- and nitrogen-use efficiencies were measured and analyzed in two wheat growing seasons from 2022 to 2024. [Results] (1) Supplementing irrigation to 75% and applying 180 kg/hm2 nitrogen (W2N2 treatment) could significantly improve the activities of soil urease and protease, reduce the activity of soil nitrate reductase, facilitated the transformation of soil nitrogen into crop absorbable forms. According to the results of variance analysis, the effects of irrigation level, nitrogen application rate and their interaction on soil nitrogen metabolism enzyme activity reached a very significant level (p<0.01). In addition, W2N2 treatment significantly reduced the residual amount of nitrate nitrogen in the 60-120 cm soil layer, and reduced the risk of soil nitrogen leaching. (2) Both W2N2 and W2N3 treatments could significantly increase nitrogen accumulation of vegetative organs, nitrogen translocation and grain nitrogen accumulation, and had the best NNI, which could meet the nitrogen requirements of wheat. The effects of irrigation level, nitrogen application rate and their interaction on NNI, nitrogen accumulation and transport of wheat reached a significant level (p<0.01). (3) The highest grain yield could be obtained by W2N2 treatment, while further increasing water and nitrogen input had no significant effect on grain yield. Different irrigation levels and nitrogen application rates had significant effects on grain yield, and the interaction between the two factors reached a very significant level (p<0.01). The decision coefficient of irrigation level and nitrogen application rate on grain yield was 0.313 and 0.485, respectively. (4) W2N2 treatment has a high water- and nitrogen-use efficiencies, that would be easy to cause a significant decrease under the continuous improvement of irrigation level and nitrogen application rate. The effects of irrigation level, nitrogen application rate and their interaction on water- and nitrogen-use efficiencies of wheat reached a significant level (p<0.01). Compared with W2N2 treatment, the two year average nitrogen fertilizer agronomic efficiency of W2N3, W3N2 and W3N3 treatment was reduced by 13.02% to 26.34%, the nitrogen utilization rate was reduced by 9.77% to 23.64%, and the irrigation water use efficiency was reduced by 2.88% to 38.10%. [Conclusion] The soil relative water content of 0-40 cm soil layer at the jointing and anthesis stages of wheat was supplemented to 75%, and nitrogen was applied at 180 kg/hm2 could significantly improve wheat grain yield, water- and nitrogen-use efficiencies, nitrogen accumulation, nitrogen translocation in vegetative organs and grain nitrogen accumulation, and had the best soil nitrogen metabolism enzyme activity and NNI. It is the best water and nitrogen management for wheat with high yield and high efficiency in Huang-Huai-Hai region.
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Soil Priority Flow Characteristics in Coal Mine Subsidence Area Under Different Rainfall Duration

guoqiaoling, huqian

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Abstract:[Objective] The research on the preferential flow characteristics triggered by cracks in the coal mining subsidence area can provide support for the scientific and rational development of water resource management and ecological management practice in the mining area. [Methods] Three cracks of the same width (3 cm) were selected in the coal mining subsidence area of Shenfu-Dongsheng Coal Field to carry out the staining tracer test with the same rainfall intensity and different rainfall durations. Processing software such as Adobe Photoshop 2020, Image Pro Plus 6.0, SketchUp Pro 2019, and Auto CAD 2019 were used to analyze the preferential flow characteristics of cracks under different rainfall calendars. [Results] (1) the soil volumetric water content, porosity, and saturated hydraulic conductivity in the priority flow occurrence area of the Shenfu-Dongsheng coal mining collapse area were greater than those in the non-priority flow area, and the volumetric weight and field water-holding capacity were less than those in the non-priority flow area zone; (2) When the rainfall duration was 10min, 20min and 30min, the corresponding depths of substrate flow were 5cm, 8cm and 10cm, respectively; and the depths of preferential flow were 26.4cm, 47.7cm and 44.3cm, respectively. the longer the rainfall duration, the deeper the development of substrate and preferential flow; (3) In general, the staining area ratio at each test site showed a decreasing trend with the increase of soil layer depth, and the morphology showed an S shape. When the rainfall duration was short, the magnitude of change in the coloring area ratio with soil layer depth was small; when the rainfall duration was long, the fluctuation of the coloring area ratio curve increased. (4) In general, with the increase of soil depth, the number of wide staining paths was decreasing, the number of fine staining paths was increasing, and the total number of staining paths showed a tendency of increasing and then decreasing. And the longer the rainfall duration, the wider the soil staining paths at the same depth, and the number of wide paths was more. [Conclusion] The f indings can provide scientific basis for land reclamation and ecological management in coal mining areas.
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Response of soil microbial diversity, community structure, and functional potential to primary forest conversion in northwestern Hunan province

xiao huacui, Sheng Hao

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[Objective] We explore the impact of primary forest conversion on soil microbial community structure and predicting soil microbial functions, and provide theoretical reference for soil health preservation. [Methods] The subtropical typical primary evergreen broad-leaved forest and the adjacently converted conifer plantation, orchards, sloping tillage, and rice paddy were chosen in northwest Hunan province. We assessed the response of bacterial and fungal genomic diversity, community structure, and predicted functions to the primary forest conversion. [Results] Comparing to the primary forest, the bacterial diversity was decreased by 29%-34% in the cultivated lands, whereas fungal diversity was decreased by 42%-49% in the orchards. The response direction and magnitude of soil bacterial and fungal predicted function depended on the specific soil function and converted land-use type. Comparing to the primary forest, the relative abundance of global and overview maps, carbohydrate metabolism, and metabolism of cofactors and vitamins were 9%-25% higher in orchards and croplands, whereas the relative abundance of membrane transport, signal transduction, cellular community?prokaryotes were 11%-27% lower in orchard and croplands. The relative abundance of endophyte-litter saprotroph?soil saprotroph in sloping tillage were 32%-42% lower than those in the primary forest; however, the animal pathogen and plant pathogen were 10%-397% higher than those in the primary forest. No significant differences of >50% of the relative abundance of predicted microbial functions were found between the primary forest and plantations. The labile C and total N contents decreased by 25%-70% following the primary forest conversion, resulting in a 10%-86% reduction in the relative abundances of variibacter and bradyrhizobium, which was the main pathway regulating the predictive functions of soil bacteria. In addition, the predicted bacterial function is mainly regulated by soil moisture and labile organic C content, whereas the predicted fungal function is mainly regulated by soil pH, quantity of labile organic C, and nutrient availability. [Conclusion] This study suggests that the conversion of primary evergreen broad-leaved forest to Cunninghamia lanceolata plantation is relatively conducive to the maintenance of soil health and functional potential, whereas the conversion to sloping tillage can increase the risk of soil-borne diseases on crops. Our findings provide a theoretical basis for prediction regional soil health evolution and rational land planning.
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The Spatial Differentiation and Correlation of Ecological Stoichiometry Characteristics of Cynodon dactylon and Soil in the Water-Level Fluctuation Zone of the Three Gorges Reservoir Area

Xu Liwen, Wang Xiaofeng

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[Objective]Cynodon dactylon is important component and dominant species in ecosystem of the water-level fluctuation zone (WLFZ) of the Three Gorges Reservoir, which is the largest hydropower project in the word. Investigation on the spatial distribution patterns and correlations of nutrient and stoichiometric characteristics between C.dactylon and its periradical soil holds significant importance in comprehending nutrient cycling as well as species adaptation features within the WLFZ.[Methods]This study conducted a field investigation of C.dactylon and its periradical soil across 16 sections in the WLFZ of the Three Gorges Reservoir Area from Banan to Yichang. The carbon, nitrogen, and phosphorus contents in plant organs (roots, stems, leaves) and soil were analyzed to explore the spatial heterogeneity and interrelationships of the ecological stoichiometry characteristics between C.dactylon and soil.[Results](1) The soil in the WLFZ associated with C.dactylon demonstrated a distinct "nitrogen-poor and phosphorus-rich" characteristic with significant spatial variations in nutrient contents and stoichiometric ratios. Specifically, soil organic carbon, total nitrogen, total phosphorus, C/N ratio, and C/P ratio exhibited a consistent increase from upstream to downstream sections. while, N/P ratio showed relatively stable, indicating synchronized spatial changes in nitrogen and phosphorus contents in the soil. (2) From upstream to downstream of WLFZ, the carbon contents in various organs of C.dactylon exhibited a decreasing trend, while nitrogen and phosphorus contents showed significant increasing patterns. This trend could be attributed to intensified sedimentation and resultant higher soil nutrient supply levels in the downstream WLFZ with the prolonged flooding time. Notably, the nitrogen content in the leaves demonstrates a degree of spatial stability, suggesting that C.dactylon could absorb nitrogen efficiently and meet its leaf nitrogen requirements prioritizly under nitrogen-deficient conditions. (3) Generally low variations in the stoichiometric ratios in organs of C.dactylon were found. However, the variability in C/N and C/P ratios in roots and stems were slightly strong than that in leaves, suggesting that C.dactylon has evolved a strategy maintaining stable physiological functions in leaves. (4) There were significant correlations of the nutrient contents between C.dactylon and soil, with the nitrogen supply of soil being the key factor influencing the variation of nutrient contents in C.dactylon. The correlations of stoichiometric ratios between C.dactylon and soil is relatively weak. (5) C.dactylon in the WFLZ generally exhibited strong homeostasis with the homeostasis index decreasing from upstream to downstream.[Conclusion]In the context of changing water inundation patterns, the nutrient contents in C.dactylon and soil exhibit significant spatial variations and cooperative association, implying that the spatial evolution of soil nutrients has a profound impact on the ecological stoichiometry characteristics of C.dactylon. While, the C.dactylon exhibits limited spatial differentiation in stoichiometry, indicating its strong adaptability to the heterogeneous soil conditions through adjustments in nutrient demand strategy. The feedback relationships of stoichiometry between C.dactylon and soil may exhibit instability under periodic waterlogging stress in WFLZ.
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Elementary Study on Gully Classification on the Qinghai-Tibet Plateau

Li Jianjun, Jiao Juying

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[Objective] Traditional gully classification systems focus on agricultural landscapes. However, on the Qinghai-Tibet Plateau, where human activity is limited, gullies primarily occur in natural landscapes. Therefore, it is necessary to propose a tailored gully classification system that is suited to the natural landscapes of the Qinghai-Tibet Plateau. [Methods] Extensive field investigations were conducted in typical regions of the Qinghai-Tibet Plateau, including the Yarlung Zangbo River and its two tributaries, the Southeast Tibet, the Qiangtang Plateau, the Three-River Headwaters region, the Hehuang Valley, the Qaidam Basin, and the Qilian Mountains. These field studies were complemented by indoor interpretations using sub-meter high-resolution remote sensing imagery. [Results] Various landforms that resemble but are not gullies in terms of genesis or morphology were identified and distinguished. The gullies were classified based on multiple criteria, including scale, genesis, the landform in which they developed, and morphology. The gullies were classified by scale into small, medium, large, and giant gullies; by genesis into rainfall-runoff gullies, snowmelt-mudflow gullies, glacial gullies, permafrost thermal gullies, and human activity gullies; by the landform in which they developed into steep-slope gullies, valley-bottom gullies, gentle-slope gullies, cliff gullies, terrace gullies, tableland-edge gullies, and tableland-surface gullies; and by morphology into straight gullies, curved gullies, spoon-shaped gullies, strip-shaped gullies, widened gullies, narrow-long gullies, wide-short gullies, radial gullies, parallel gullies, and dendritic gullies. [Conclusion] This paper preliminarily proposes a comprehensive gully classification system based on multiple criteria suitable for the characteristics of the Qinghai-Tibet Plateau. It suggests using scale as the primary basis for comparison with gully classification systems in other regions, such as the Loess Plateau. This provides support for soil erosion research and ecological environment protection on the Qinghai-Tibet Plateau.
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Spatial Coupling Pattern of Soil Layer and Upper Epikarst Zone in a Dolomite Hillslope

TANG Xufang, Huang Xuhan

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Based on the in-depth geotechnical trench excavation tests on the full slope scale of typical dolostones, the spatial coupling development characteristics between the soil and upper epikarst zone on dolostone slopes have been preliminarily clarified combined with the field measured data,. The results indicate that: 1) The thickness of soil and upper epikarst zone on dolomite slopes gradually increases down the slope. The average thickness of the upper epikarst zone on a slope scale is 50 cm, with an average volume of 0.47 m3/m2, accounting for 43.9% of the total volume of the soil profile, indicating that the ecological function of epikarst in karst regions is extremely important; (2) The geotechnical structure of the dolomite slope exhibits strong spatial heterogeneity. The spatial heterogeneity of the underlying upper epikarst zone (C+C0 is 18.88) is significantly higher than that of the overlying soil layer (C+C0 is 15.84) ; (3) The overall soil thickness,,especially the thickness of soil layer B, is significantly positively correlated with the degree of weathering in the epikarst, indicating that the increase in soil thickness promotes the weathering of the underlying epikarst, and there is a clear coupling and collaborative development relationship between soil and upper epikarst zone The soil and upper epikarst zone in karst regions have evolved in a mutually reinforcing manner, with the epikarst below the soil layer potentially acting as an essential substrate for the karst ecosystem. The soil thickness and the depth of its B horizon exhibit a significant positive correlation with the thickness of the epikarst, which may be critical parameters for predicting epikarst depth on karst slopes. The evaluation of karst water and soil resources demands a holistic approach that encompasses both soil and the underlying bedrock weathering layer.
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Effects of no-tillage with mulching during fallow on soil physical characteristics and potato yield in different precipitation years

hangu, lirong

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[Objective] Aiming at the problems of equal emphasis on spring drought and spring cold in the southern mountainous areas of Ningxia, and shallow effective soil surface. [Method] From 2014 to 2016 three different no-till mulching modes were set up after autumn crops were harvested for three consecutive years: No-tillage straw mulching (NJ), no-tillage mulching film (ND), no-tillage no mulching (NB), and no-tillage no mulching as control (CK). The effects of no-tillage with mulching mode on soil moisture retention, precipitation utilization characteristics and potato yield under different precipitation years in arid region of south Ningxia were analyzed. [Result] The soil water storage and water storage efficiency in fallow period were the highest under ND treatment, which increased by 7.60% and 140.35% compared with CK, respectively. NJ treatment was the highest in normal year and dry year, which was increased significantly by 11.18% and 65.43% and 28.42% and 122.72% compared with CK, respectively. NJ treatment had the highest soil water storage in normal and dry years, which was increased by 10.51%, 12.89% and 20.04%, respectively, compared with CK treatment. ND treatment significantly increased soil water storage by 11.42% compared with CK at seedling stage in the relatively dry year. The decrease of soil water storage in ND treatment was 22.26% and 36.57% higher than CK treatment in early growth stage (sow-budding stage) and middle growth stage (budding stage - expanding stage) of relatively dry years, respectively. NJ treatment significantly increased by 1.21 times, 7.14 times and 13.91%, respectively, compared with CK treatment, in the late growth period (expanding to harvest period) and middle and late growth period (emerging bud to harvest period) of the relative drought years and drought years, respectively. Potato yield was the highest in NJ treatment, which was significantly increased by 51.80% compared with CK treatment. In normal year and dry year, ND treatment significantly increased by 6.35% and 71.36% compared with CK treatment, respectively. Correlation analysis showed that the decrease of soil water storage from tuber formation to tuber expansion played an important role in potato yield, yield composition and water use efficiency. The annual precipitation use efficiency, precipitation use efficiency and water use efficiency in growth period were better under NJ treatment than CK, which were significantly increased by 51.79%, 51.80% and 50.52%, respectively. ND treatment significantly increased by 35.14%, 36.14% and 21.61% compared with CK treatment in normal year and dry year, respectively. [Conclusion] no-tillage combined with mulching can effectively improve soil water storage and soil moisture retention during fallow period and growth period, and significantly improve potato yield and water use efficiency. The no-tillage and straw mulching mode can realize continuous potato yield and water use efficiency.
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Transpiration and soil hydrothermal studies of orchards based on dynamic parameterization of leaf area index

YANG Yumeng, GAO Xiaodong

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[Objective] As a key parameter in the simulation study of ecosystem water cycle process, the rapid dynamic simulation of the Leaf Area Index (LAI) can solve the limitation that the coupled soil water-vapor-heat-air model STEMMUS (Simultaneous Transfer of Energy, Mass and Momentum in Unsaturated Soil) can only use fixed or measured as an input parameter. [Methods] In this paper, the "plant leaf area development sub-module" in EPIC model was coupled with the STEMMUS model, and the model was calibrated and validated using the measured fruit tree transpiration, soil moisture and soil temperature data under the apple growth conditions in the mountain apple Experimental demonstration base of Zizhou County in 2019 and 2020, so as to evaluate the applicability of the coupled model on the Loess Plateau. [Results] The results showed that by optimizing the plant growth parameters, the coupled leaf area development sub-module of the STEMMUS model significantly improved the simulation accuracy of the transpiration and water consumption process of apple trees, with the normalized root mean square error (NRMSE) of the calibration and validation years increasing from 40.2% and 61.9% in the original model to 30.0% and 33.2% in the coupled model, and the mean absolute error (MAE) increasing from 0.52 mm d-1 and 0.64 mm d-1 to 0.42 mm d-1 and 0.38 mm d-1. Meanwhile, the coupled model can better simulate the soil hydrothermal dynamic processes in apple orchards, and the NRMSE of simulated soil water content and soil temperature at the calibrated period and validation period ranged from 1.4% to 32.9% and 2.9 to 9.5%, and the MAE ranged from 0.13 to 4.26 cm3 cm-3 and 0.34 to 1.49°C, respectively. [Conclusion] The high agreement between the simulated and measured values indicates that the coupled model can accurately describe the dynamic growth process of fruit tree leaf area and the ecohydrological process of orchard in the Loess Plateau, and this study can provide technical support for the research of the ecohydrological process of orchard in Loess area.
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Mechanisms of Soil Physical Crust Crack Formation

WANG Ze, WANG Jian

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[Objective] Soil physical crusting is a common obstructive phenomenon on exposed surfaces, leading to shrinkage cracks as the soil dries, directly affecting soil moisture retention and utilization. This study aims to clarify the development patterns of cracks in physical crusts. [Method] Artificial rainfall was employed to simulate the formation of different types of physical crusts, followed by crack formation during the drying process. Parameters such as crack area, perimeter, length, and width were measured using a paraffin filling method, and the geometric characteristics and spatial variations of cracks in depositional crusts (DC) and structural crusts (SC) under different conditions were quantitatively analyzed. [Results] The results indicate that (1) cracks in depositional crusts (DC) exhibit significantly higher geometric parameters compared to those in structural crusts (SC); (2) with increasing rainfall duration, the crack shape coefficient and density decrease, while the average crack width increases; (3) three types of lateral shrinkage cracks were identified: penetrating shrinkage (PS), interlocking shrinkage (IS), and suspended shrinkage (SS). As rainfall duration increases, the proportion of PS increases, while IS and SS proportions decrease; (4) as soil depth increases, cracks in depositional crusts display a stepped decrease and a brief increase under different rainfall durations, while cracks in structural crusts show an initial sharp decrease followed by a gradual decline. [Conclusion] The type of crust and rainfall duration are crucial factors influencing crack development. This study highlights the impact of crusting on crack formation, suggesting timely field management practices to modify water infiltration and evaporation, providing technical support for effective field management.
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Spatial and Temporal Changes and Dynamic Driving Forces of Soil Water Erosion in Arid and Semi-arid Regions of China from 1990 to 2020

CHEN Shuo, ZHAO Wenwu

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[Objective] The ecological environment in China''s arid and semi-arid regions is highly vulnerable, with soil erosion posing a significant challenge. In light of climate warming, investigating the current state of soil water erosion in these areas is of critical importance.[Methods] This study based on the RULSE model to calculate the model factors and soil water erosion modulus for China''s arid and semi-arid regions for the years 1990, 2000, 2010, 2015, and 2020, and conducts an accuracy validation (R2 = 0.60).Establishing on these calculations, the optimal parameter geographic detector is utilized to analyze the dynamic driving forces and changes associated with both single and interaction factors.[Results] The key findings are as follows: (1) From 1990 to 2020, the average annual soil water erosion in China''s arid and semi-arid regions amounted to 4.71×1010 kg , exhibiting a slight upward trend in the soil water erosion modulus at a rate of 0.0007 t·hm?2·a?1. (2) The intensity of soil water erosion is predominantly characterized by slight to moderate erosion. The proportion of areas experiencing increases and decreases in soil water erosion intensity is both rising, while the proportion of areas with stable soil water erosion intensity is declining. (3) Slope, precipitation, and precipitation erosion force are identified as the primary single driving factors of soil water erosion in these regions from 1990 to 2020, with these three factors alternating as the main dominant factor throughout the study period. Interactions between any two selected factors enhance the explanatory power regarding soil water erosion, with the interaction between slope and precipitation erosion force consistently serving as the primary dominant interaction factor during the study period.Overall, the soil water erosion situation in China''s arid and semi-arid regions is experiencing slight deterioration.[Conclusion] To effectively address this issue, it is crucial to consider topographical and precipitation characteristics concurrently when implementing management measures aimed at improving soil water erosion conditions in arid areas.
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Effects of tillage disturbance on the slope shape and micro-topographic features on typical sloping cropland slopes of southwestern alpine-canyon area

Wang Jiaqi, Wangyong

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[Objective] The objective of this study is to investigate the effects of various tillage operations on slope shape and micro-topographic features on typical sloping cropland slopes of southwestern alpine-canyon area. [Methods] 50-time conventional tillage and contour tillage events were applied to rectangular plots (5 m × 20 m) with a slope of 15° to examine the impacts of tillage disturbance on the slope shape and micro-topographic features by combining the stylus method and 3D laser scanning technology. [Results] After 50-time conventional tillage, the slope shape gradually evolved from a linear slope to a “”-type composite slope, while contour tillage evolved to a “”-type . After 50- time successive tillage, the range of soil loss under conventional tillage and contour tillage accounted for 15% and 11%, and the range of accumulated soil accounted for 13% and 6% on the whole slope, respectively. The two kinds of tillage disturbance patterns caused significant changes in the surface roughness and topographic undulation on the slope, and the degree of change of conventional tillage was greater than that of contour tillage. The average thickness of the soil loss by conventional tillage and contour tillage were 1.17 and 0.45 cm/time, respectively. The indirect effect of tillage disturbance patterns on soil loss was the largest, while the direct effect of tillage frequency on soil loss was the largest. [Conclusion] Tillage frequency and tillage pattern were the most important factors affecting slope shape and micro-topographic features. As the frequency of tillage increased, and the amount of soil loss gradually increased.
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Effect of freezing on wind erosion resistance of sand dune soil

lijinrong

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To investigate the effect of winter soil freezing on soil erodibility and anti-erodibility in the Yellow River section of the Ulan Buh Desert. we conducted particle size screening experiments on dry, wet, and frozen sand on the windward slope of mobile dunes, along with shear strength tests before and after freezing. The results show that sand particle sizes at three positions on the dunes increased due to the bonding effect of water. The particle size peak shifted from 0.15~0.2 mm to 0.3~0.355 mm, with approximately 35.12% of fine sand particles bonding to form larger, medium sand particles. After freezing, very coarse sand emerged, and the particle size peak shifted to 0.5~0.6 mm.Sand particles bonded and coarsened, forming coarse and very coarse sand (52.02%). The proportion of highly erodible particles decreased to 23%～36%, while moderately erodible particles increased to 53%～63%, and hard-to-erode particles increased to 2%～17%. As soil moisture in the dunes increased, the cohesion of frozen soil significantly increased (p < 0.05), along with shear strength and erosion resistance (p < 0.01). Freezing coarsened sand bonds in dune soil, increasing the proportion of moderately and hard-to-erode particles (up to 70%), shear strength by 0.14%～13.07%, and erosion resistance by 0.6%～2.2%. Freezing can effectively improve the corrosion resistance of sand dune soil and inhibit wind erosion. The research results can provide a theoretical basis for the wind erosion resistance of dune wind erosion '' bare spot '' in freezing period.
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Macro-micro evolution characteristic function of stabilized-loessunder dry-wet cycle effects

JIAO Yuanfan, YAN Changgen

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Dry-wet cycles significantly impact the stability of loess slopes. To understand the durability of stabilized-loess slope protection materials under dry-wet cycles, experiments on direct shear, permeability, and microscopic properties were conducted. Macroscopic properties evolution and microscopic structural damage were studied, leading to the establishment of characteristic functions describing the relationship between macroscopic and microscopic properties. Results showed that biopolymer content mitigated mechanical property deterioration in stabilized-loess, with its effectiveness positively correlated to dosage. Biopolymer content also influenced permeability changes, inversely proportional to dosage. Dry-wet cycles led to loess cementation failure, particle damage, and pore enlargement, mitigated by biopolymer which delayed damage and altered pore development. Prediction accuracy of characteristic functions exceeded 95%, highlighting porosity and large pores (>32μm) as significant factors impacting mechanical properties and permeability, respectively.
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Study on Landscape Ecological Security Assessment and Zoning Management of Karst Mountainous Landscape in Southwest China

YuZhongyuan, HuangYizhong

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Wenshan City, situated in the southwest of China, exhibits a typical karst mountain terrain. It constitutes a crucial ecological function area in China, featuring a fragile ecological environment and a high susceptibility to ecological variations. Grounded on the attributes of the karst mountain landscape, this paper has erected a target-comprehensive-project-index assessment index system for landscape ecological security. By employing the geometric mean and the InVEST model, the ecological sensitivity and significance of system services were appraised at two comprehensive levels. Subsequently, the ecological security target level was evaluated, ecological functional zones were demarcated, and differentiated management measures were proffered. The findings suggest that: (1) The regions highly susceptible to soil erosion, geological disasters, and rocky desertification are predominantly distributed in the eastern and southern areas; Water conservation, soil conservation, and biodiversity conservation were generally inadequate, and the regions of greater significance were mainly situated in the southwest. (2) The outcomes of the integrated ecological sensitivity and significance of system services disclosed that the ecological quality of the southwest region surpassed that of other regions; The overall level of landscape ecological security is low, with a general tendency of being high in the southwest, low in the east and south, and mediocre in the north. (3) The ecological function zone of Wenshan City was categorized into four types of ecological function zones, namely the rock desertification ecological function restoration zone, the urban ecological coordination construction zone, the biodiversity functional protection zone, and the water conservation and soil conservation function enhancement zone. Rational management measures and suggestions were advanced based on the ecological predicaments of each region.
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Analysis of Soil Erosion Intensity Change Trajectories and Their Driving Factors in Yunnan Province Based on an Improved Stability Mapping Method

MA Dongling, PENG Shuangyun

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[Objective] This study aims to elucidate the change trajectories of soil erosion intensity in Yunnan Province from 1990 to 2022, analyze the types of changes and their driving factors, and provide a scientific foundation for effective soil erosion control strategies. [Methods] Quantitatively assess soil erosion intensity conditions in Yunnan Province based on the RUSLE model and capture dynamic characteristics by introducing interannual change rates. Use an improved Stability Mapping Method (STD), combining change rates and frequencies to identify soil erosion intensity change trajectory types. Analyze the contribution of driving factors using the Random Forest model and compare the characteristics of driving factors across different trajectory types. [Results] The interannual change trend of soil erosion in Yunnan Province was mainly stable, with significant changes observed in areas of substantial decrease and increase. Soil erosion intensity change trajectories exhibited significant spatial differentiation, with cyclical trajectories being the most prevalent (53.90%), followed by non-continuous stepwise (14.78%) and fluctuating types (14.08%). Precipitation, slope, population density, GDP, and vegetation cover were the main driving factors affecting soil erosion intensity trajectory changes, with contributions of 17.92%, 14.56%, 12.52%, 12.67%, and 9.41%, respectively. There were differences in driving factors across different trajectory types. Areas with cyclical and non-continuous stepwise trajectories had higher precipitation and slopes, while stepwise trajectory areas had higher farmland coverage and lower forest coverage. [Conclusion] The characteristics of soil erosion intensity trajectory changes in Yunnan Province are significant, with spatial heterogeneity in driving mechanisms. Therefore, soil erosion control strategies should reflect regional differentiation and specificity, and adopt location-specific measures based on regional characteristics. The STD trajectory partitioning method based on change rates effectively captures the dynamic changes in soil erosion, providing new insights for monitoring, early warning, and partitioned control of soil erosion.
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Greenhouse Gas Mitigation and Yield Response to Biochar-Microbial Amendment in Saline Soil

QIN Jianjie, QU Zhongyi

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To investigate the effects of combined application of biochar and microbial fertilizer on greenhouse gas emissions and sunflower yield in saline-alkali soil under plastic film mulching and drip irrigation. Field experiments were conducted in saline-alkali soil in the Hetao Irrigation Area of Inner Mongolia, with different combinations of biochar (0, 7.5, 15 t/hm2) and microbial fertilizer (0, 112.5, 225 kg/hm2). Greenhouse gas emissions were monitored using static chamber-gas chromatography method. Changes in soil physicochemical properties, global warming potential (GWP), and sunflower yield were analyzed. The results showed that: (1) Compared with the control treatment (0 t/hm2 biochar + 0 kg/hm2 microbial fertilizer), the treatment of 7.5 t/hm2 biochar + 225 kg/hm2 microbial fertilizer increased soil organic carbon, available phosphorus, and available potassium contents by 63.9%, 155.7%, and 46.8%, respectively. (2) Compared to the control treatment, the treatment with 7.5 t/hm2 biochar + 225 kg/hm2 microbial fertilizer reduced cumulative CO2 emissions from 4373 kg/hm2 to -394.3 kg/hm2, increased cumulative CH4 emissions from -0.08 kg/hm2 to 0.1 kg/hm2, reduced cumulative N2O emissions from 0.23 kg/hm2 to -0.09 kg/hm2, and decreased GWP from 4438.3 kg/hm2 to -417.2 kg/hm2. (3) Under the treatment of 15 t/hm2 biochar + 225 kg/hm2 microbial fertilizer, sunflower yield reached 4137.5 kg/hm2, increased by 39.4% compared with the control treatment (2968 kg/hm2). (4) Mantel test analysis revealed that sunflower yield was extremely significantly correlated with soil physicochemical properties (p < 0.01); CO2 emissions were significantly correlated with ammonium nitrogen and moisture content, N2O emissions were significantly correlated with nitrate nitrogen, and CH4 emissions were extremely significantly correlated with nitrate nitrogen (p < 0.05). The combined application of biochar and microbial fertilizer can simultaneously improve saline-alkali soil, reduce greenhouse gas emissions, and increase sunflower yield, with 7.5 t/hm2 biochar + 225 kg/hm2 microbial fertilizer being the optimal combination. This technique provides a new strategy for reducing greenhouse gas emissions and increasing crop yields in saline-alkali agricultural production.
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Soil Quality Assessment of Five Typical Forest Stands in the Dianchi Lake Basin Based on MDS

jinzhehao, Liu Zhiqin, Wang Keqin

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Soil quality is a critical indicator of ecosystem health and sustainable land management. The Dianchi Lake watershed, as a key ecological area in the southern plateau of China, has recently faced threats to soil quality due to changes in land use practices. This study aims to assess the soil quality of five typical land use types in the watershed and investigate the effects of different vegetation types on soil physicochemical properties. The minimal dataset method (MDS) and principal component analysis (PCA) were employed to process the data and identify key soil quality indicators.The results indicate that: (1) A comparative analysis of the physicochemical properties of soils in five typical forest types in the Dianchi Lake watershed revealed that the soil quality of mixed forests, pure forests of Chinese pine, and pure forests of Eucalyptus deglupta significantly surpassed that of artificial eucalyptus forests. The mixed forest exhibited higher organic matter and total nitrogen content, while the Eucalyptus deglupta forest demonstrated strong water retention capacity. The pure Chinese pine forest performed well in nutrient supply and fertility maintenance. The soil quality of shrub forests was intermediate, with zmoderate levels of organic matter and total nitrogen. (2) The MDS was used to evaluate the soil quality index (SQI) across three soil layers for different forest types. Results showed that the SQI was highest in the pure Chinese pine forest at the 0-20 cm layer, in the Eucalyptus deglupta forest at the 20-40 cm layer, and in both the Eucalyptus deglupta and mixed forests at the 40-60 cm layer. The average SQI values were as follows: Eucalyptus deglupta (0.60) > Chinese pine (0.54) > mixed forest (0.47) > shrub forest (0.33) > artificial eucalyptus (0.20). (3) The MDS analysis demonstrated a strong correlation with the total dataset (TDS), with a fitting performance of R2 = 0.69, confirming the effectiveness of MDS in soil quality assessment.The findings provide a scientific basis for soil management in the Dianchi Lake watershed, recommending the promotion of Eucalyptus deglupta mixed planting in water conservation areas and regions severely affected by soil degradation to maintain soil organic matter and improve water retention capacity. Additionally, it is suggested to implement mixed planting and rational irrigation measures for artificial eucalyptus forests to restore soil quality, while enhancing the coverage and soil conservation capacity of shrub forests to sustain soil fertility and ecological functions.
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Multi scenario simulation of land use and carbon stock assessment in the Pearl River Basin in the next decade

lanjian

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[Objective]The temporal and spatial changes of land use and carbon storage in the Pearl River Basin in the past 20 years and the next 10 years were analyzed, in order to provide a reference for the optimization of land use pattern and ecosystem carbon sequestration management in the Pearl River Basin. [Methods]Based on the land use data of 2002, 2012 and 2022, this paper analyzes the changes of land use types, uses the PLUS model to simulate the land use pattern under the natural development scenario, cultivated land protection scenario and ecological protection scenario in 2032, and uses the InVEST model to evaluate the changes of ecosystem carbon storage under the three scenarios. [Results]The results show that the land types in the Pearl River Basin have changed greatly in the past 20 years, and the one-way conversion of cultivated land to construction land and the two-way conversion between cultivated land and forest land are the main characteristics of land use change in the Pearl River Basin. During the same period, the carbon storage of terrestrial ecosystems showed a downward trend as a whole, with a decrease of 0.52%. The carbon storage projection in 2032 shows that the carbon storage under the ecological protection scenario is significantly higher than that under the cultivated land protection scenario and the natural development scenario, which are4.84×106 ton和10.22×106ton higher, respectively. [Conclusion]Therefore, when formulating land use planning in the future, decision-makers should consider the balance between economic development and ecological protection, strengthen the concept of ecological protection and green development in river basins, increase the function of land carbon storage, and help achieve the "double carbon" goal and regional sustainable development.
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The Effect of Wind Speed on the Characteristics of Rill Erosion on Windward Slope under Rainfall Conditions

Zhang Wenbo, Han Yuguo

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[Objective]To elucidate wind-induced rill erosion characteristics on the windward slope, artificial simulated wind-driven rain experiments were conducted.[Methods] The study investigated changes in water and sediment processes as well as rill morphology under different wind speed conditions (0, 3, 5, and 7 m/s).[Results] Results indicated that, compared to slopes without wind, the windward slope exhibited a 20.59%～47.06% increase in flow generation time and a 33.10%～137.78% increase in the occurrence of falling ridges. The average slope flow velocity decreased by 12.86%～22.53%. Runoff and sediment production rates notably decreased with increasing wind speed(p<0.05).The runoff production rate on windward slopes followed a similar trend under different wind speeds, gradually increasing with rainfall before stabilizing over time, with no significant differences observed among stages at different wind speeds. Sediment yield rates increased rapidly with prolonged rainfall duration, followed by a gradual decrease and stabilization. Nodes of sediment yield rate changes aligned closely with the occurrence of falling ridges.Rill dimensions (width, depth, fluctuation degree) decreased with rising wind speed. The width-depth ratio and rill inclination ranged from 1.4 to 1.69 and 13.47 to 14.76 degrees, respectively, increasing with higher wind speeds. Under various wind speed conditions, rill volume, splitting degree, and density ranged from 4.39 to 10.27 m3, 0.024 to 0.042, and 2.03 to 2.92 m/m2, respectively, all decreasing with increasing wind speed.[Conclusion]The volume, density, and degree of fragmentation of rills are all significantly positively correlated with the amount of slope erosion, making them the preferred indicators for characterizing the morphology of rills on windward slopes.
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Spatial and temporal variation and potential of NPP in terrestrial ecosystems in Shaanxi Province from 2000 to 2020

Wang, wang, DengLei

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In the context of the "dual- carbon" goal, accurately assessing the status, rate and potential of carbon sequestration in terrestrial ecosystems is crucial for achieving “carbon neutrality”. Shaanxi province, which spans three climatic zones and have a large difference in climate between north and south, with abundant vegetation types. In recent years, the vegetation coverage in Shaanxi has been further improved due to the implementation of various ecological projects (Grain for Green, Three-North Shelterbelt, etc.). Its vegetation coverage reach up to 60.7%, what resulted in huge carbon sequestration capacity. Net primary productivity (NPP), as one of the most important indicator to reflect the carbon sequestration capacity of vegetation, there are few studies on spatial and temporal dynamic changes of NPP and the spatial distribution of NPP potential in the future in Shaanxi Province. Based on these, we evaluated the temporal and spatial distribution characteristics of vegetation NPP and its potential in Shaanxi Province through CASA model and neighborhood similarity spatial distribution method. The results showed that: (1) Total carbon sequestration by vegetation increased by 333Tg, with an increase of 48.5% from 2000 to 2020 in Shaanxi Province. (2) NPP was higher in the south and lower in the north, with the highest or lowest value in the middle. The average value in 2000 and 2020 were 333.2 g C/m2 and 494.8 g C/m2, respectively, with a total increasement of 161.6 gC/m2, and the increase amplitude shows a distribution trend of high in the north and low in the south in Shaanxi. (3) The carbon sequestration potential was 2304 Tg which increased by 41.30% compared with the 2020. The spatial distribution trend is gradually decreasing from south to north, and the spatial distribution characteristics show high spatial autocorrelation characteristics, but the local differences are large. This study calculated the spatial and temporal dynamic changes and predicted potential spatial distribution characteristics of NPP in the regional scale ecosystem in Shaanxi, which can provide a evaluation systematic and theoretical reference for scientific evaluation and improvement of regional carbon sink capacity.
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Identification of key areas for ecological restoration and division of restoration zones in Qinghai Province

MA Zeyu, LI Peng

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[Objective] Identifying priority spaces for ecological restoration and curbing ecological degradation based on the governance idea of "holistic protection, systematic restoration and comprehensive management" is an important measure for the coordinated development of regional socio-economics, the construction of a firm ecological security barrier and the promotion of ecological civilization.[Methods] This paper takes Qinghai Province as the study area, reflects the urbanisation process through land use intensity and land use centre of gravity shift, quantitatively evaluates seven ecosystem services, ecological sensitivity and habitat degradation from 2005 to 2020, and proposes to identify the priority space for ecological restoration based on the cluster of ecosystem services, ecological sensitivity and habitat degradation. We proposed to identify ecological restoration priority spaces based on "ecosystem service cluster, ecological sensitivity and habitat degradation degree", and combined internal defects and external coercion to delineate five types of ecological restoration priority zones and propose corresponding restoration strategies.[Results] The depth of water production in Qinghai Province from 2005 to 2020 will be 125.1 mm, 106.9 mm, 80.0 mm and 135.4 mm respectively, and the depth of water retention will be stabilised at about 15 mm. Grain output will increase from 1.42 t/hm2 to 2.02 t/hm2, wind and sand control capacity will increase from 2.42 t/hm2 to 4.59 t/hm2, and soil conservation capacity will decrease from 85.9 t/hm2 to 65.3 t/hm2; The ecosystem service clusters in Qinghai Province were classified into five categories: Harmony of Habitat, Harmony of Soil and Water, Conservation of Ecological Sources, Restoration of Natural Ecology, and Functional Cluster of Wind and Sand Conservation. Based on the results of bivariate autocorrelation to identify the ecological restoration priority points, it can be seen that the key ecological restoration points and natural ecological restoration points are the main ones in Qinghai Province, accounting for 5.26% and 2.55% of the area, respectively, in which the key ecological restoration points and ecological livability clusters increase the area of the spatial distribution of the basic coincides with each other.[Conclusion] The priority areas for ecological restoration in Qinghai Province are concentrated in the ecologically fragile northwestern desert areas, high-altitude mountainous areas, water sources and river coasts and the river valley where human activities are more frequent, and in the area around Tianjun County and Xinghai-Mado-Qumalai County.
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Spatial and temporal variation characteristics of vegetation greenness in rocky desertification and non-rocky desertification areas of Chongqing

LI Hui, WEI Xingping

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The investigation of temporal and spatial variations in vegetation greenness and its response to different land use types in karst rocky desertification and non-rocky desertification areas in Chongqing is crucial for guiding ecological restoration efforts in karst regions. This study utilizes vegetation leaf area index (LAI) data and land use type information to conduct trend analysis and Hurest index calculations, aiming to analyze the temporal and spatial evolution characteristics of vegetation greenness in both rocky desertification and non-rocky desertification areas. Additionally, a land use transfer matrix is employed to quantitatively assess the impact of land use changes on vegetation greenness. The findings reveal that: (1) Vegetation greenness exhibits an increasing trend in both rocky desertification and non-rocky desertification areas, reaching maximum values of 1.36 and 1.69 respectively, with average annual growth rates of 0.014 and 0.012. (2) The dynamic changes observed in vegetation greenness within these areas demonstrate positive trends, with improvement trends accounting for 86.84% (rocky desertification)and87 .04%(non-rock ydesertificatio n). Furthermore, anti-continuous improvement trends are observed at rates of52 .82%(rock ydesertifi cation)a nd80 .29%(non-ro ckyde serti fication), indicating the primary change trajectory for future vegetation greenness. (3) The main land use types in both rocky and non-rocky desertification areas are woodland and cropland, and cropland converted from woodland is the main occurrence of degradation of vegetation greenness, while woodland converted from cropland, shrubs and grassland is the main occurrence of improvement of vegetation greenness. (4) The conversion of land use types with high Leaf Area Index (LAI) to those with low LAI resulted in a decrease in LAI and vegetation greenness, while the conversion from low LAI land use types to high LAI land use types led to an increase in LAI. In areas affected by stony desertification and non-stony desertification, the maximum reduction in total LAI transfer was 1.19×104 and 4,442.18 respectively, whereas the maximum increase was 1.50×104 and 1.71×104 respectively. The impact on total LAI from construction land, water area, and bare land area was minimal and not significant. These research findings contribute to understanding the change characteristics of vegetation greenness and its response mechanism towards land use changes in ecologically fragile areas. Furthermore, they provide a scientific basis for controlling rock desertification, ensuring ecological security, and promoting sustainable economic development in karst areas of Chongqing.
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Comparison of erosion monitoring methods in the Pisha sandstone areas of the Chinese Loess Plateau based on UAV-SfM data

LIU Yilin, LI Pengfei

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Detection of soil erosion in complex terrain and steep slopes has always been a challenge. The 3D point clouds achieved by the Unmanned Aerial Vehicle-Structure from Motion (UAV-SfM) technology provides an efficient and cost-effective method for obtaining large-scale terrain data, making it an important data source for monitoring land surface changes. However, there is a lack of comprehensive research on UAV-SfM terrain change monitoring algorithms, limiting its application in the study of soil erosion and sediment transport processes. This study assessed the accuracy of four commonly used geomorphic change detection algorithms in the Pisha sandstone area of the Loess Plateau, including Digital Elevation Model of Difference (DoD), Cloud to Cloud (C2C), Cloud to Mesh (C2M), and Multiscale Model to Model Cloud Comparison (M3C2). . Point cloud data employed to operate the four algorithms were produced using the SfM technique based on images acquired by UAV between July 2022 and March 2023. The impact of point density changes in the accuracy of the employed algorithms was also investigated. Results showed that all four algorithms were capable of effectively monitoring large surface changes. Among them, the M3C2 algorithm performed the best with the highest accuracy (R2 = 0.953, p <0.01) and the lowest error (MAE = 0.0161m, MRE = 3.37%, RMSE = 0.0194m), followed by the C2M algorithm. The DoD algorithm was only suitable for flat areas and yielded overestimated results for steep sloping areas. The M3C2 and C2C algorithms were sensitive to point cloud density, while the C2M and DoD algorithms were lesssensitive. The study provided a useful reference for the selection of erosion monitoring methods for the Pisha sandstone areas.
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Influence of Headcut Height on the Developmental Processes of Downstream Plunge Pool on a Granite Red Soil Slope

WANG Jianyu, DENG Yusong

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The development of plunge pool is a key process of headcut erosion. To clarify the effect of headcut height on the developmental processes and dynamical mechanisms of plunge pool. The study investigated the developmental processes and dynamical mechanisms of plunge pool under different headcut heights (25 cm, 50 cm, 75 cm, 100 cm, and 125 cm) on a granite red loam slope. The results show that: (1) As the height of the headcut increases, the Re, τ, ω and the jet parameters: Vbottom, , Ekbottom, and show an increasing trend. (2) After the laterite soil layer scouring to form a "V" type of small plunge pool mainly, with the increase in the flow of the form of plunge pool gradually increased, but it is difficult to form a large area of the plunge pool, and the laterite soil layer is more stable than the sandy soil layer. During the scouring process of the sandy soil layer, the development of headcut bed drop points was more obvious, and when the flow rate increased to 120 L/min, the degree of headcut bed fragmentation was gradually drastic, and the outline of the drop points was gradually clearer, and the cross-sectional area increased (3) The study characterizes the degree of erosion of drop caves through cross-sectional area. Random forest algorithm and Shapley values are used to construct the model and characterize the relationship between the parameters. The results showed that in the laterite layer, Fr, ω, Ekbrink, and Re were negatively correlated with the cross-sectional area; and in the sandy soil layer, Fr and were negatively correlated with the cross-sectional area. Higher accuracy of predictive models constructed by the random forest algorithm (LCCC=1.02, R2adjusted=0.876 and 0.868). The study provides a theoretical basis for revealing the mechanism of plunge pool development, improving the theoretical system of gully erosion, and preventing and controlling soil erosion in the red soil area.
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Effect of Rock Strata Dip on Soil Detachment Capacity of Different Land Use Types in karst Trough Valley Area

jianglisha, Gan Fengling

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Abstract: [Objective] This study aims to explore the influence mechanism of rock strata dip on soil erodibility in karst gorge areas, and provide reference for preventing and controlling water and soil erosion in karst trough valley area. [Methods] The study focuses on the dip/anti-dip slope of Qingmuguan karst trough valley area in Chongqing City. Through flume erosion experiments, we analyze the differences in soil erodibility between different land use types on dip/anti-dip slopes, and investigate the impact of soil physicochemical properties on soil erodibility.[Results] (1) Both dip/anti-dip slopes shows a significant negative correlation with organic matter content, >0.25 mm water-stable aggregates content, and total nitrogen content (P<0.05). In particular, anti-dip slope have higher organic matter content, >0.25 mm water-stable aggregates content, and total nitrogen compared to dip slope. (2) Soil erodibility is higher on dip slope than anti-dip slope for all four land use types studied. Additionally, grassland has lower comprehensive scores of soil erodibility than pepper fields, cornfields, and bare land on both dip/anti-dip slopes. (3) Based on stepwise multiple regression analysis results, prediction models for soil erodibility on dip/anti-dip slopes were established using organic matter content and >0.25 mm water-stable aggregates content as predictors with determination coefficients R2 of 0.77 and 0.85 respectively.[Conclusion] In summary, grassland has the lowest soil erodibility among all land use types studied regardless of dip/anti-dip slopes in karst trough valley. Therefore, in order to prevent soil erosion and promote ecological restoration in karst trough valley, it is necessary to cultivate the land reasonably and increase grassland coverage appropriately, thus enhancing the soil''s resistance against erosion.
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Transformation of Chemical Forms and Migration Characteristics of Cadmium and Selenium During Soil Formation on Black Rock Series

REN Bai-lin, ZHANG Ming-kui

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Black rock series contains high amounts of cadmium and selenium. During weathering and soil formation on the rocks, the chemical form transformation and release of cadmium and selenium from the rocks can have an impact on the surrounding ecological environment. In this study, a black rock series distribution area of Hetang formation of the Lower Cambrian was selected in Northwest Zhejiang. By collecting horizonal soil samples from soil profiles along different parts of the terrain (hill upslope, hill middle slope, hill downslope, inter hill valley bottom and valley terrace), the quantity and chemical form transformation patterns of cadmium and selenium during the process of weathering soil formation and weathering material migration of the black rock series were discussed. The results showed that total cadmium and total selenium in the soils decreased from parent rock to soil. The loss of cadmium and selenium in the weathered matter of black rock series increased with the increase of transportation distance along the hilly slope, and the loss of cadmium and selenium in the process of evolution from slope deposit to diluvium was greater than that from residual to slope deposit. The cadmium and selenium lost from the weathered materials could affect the content of cadmium and selenium in the topsoil derived from the alluvial of the downstream river in the way of water diffusion, but the degree of influence decreased with the increase of distance. With the increase of the transportation distance of weathered materials and the evolution of soil, the transformation of carbonate bound cadmium and residual cadmium to water-soluble cadmium, exchangeable cadmium, organic matter bound cadmium and oxide bound cadmium occurred. The residual selenium was gradually activated and transformed into exchangeable selenium, organic matter bound selenium and oxide bound selenium. The results also showed that soil water-soluble cadmium, exchangeable cadmium (selenium) and organic matter bound cadmium (selenium) increased toward the surface. The organic enrichment of selenium and topsoil was more obvious than that of cadmium. The results indicates that the weathering of black rock series could not only directly affect the content of soil cadmium and selenium in its distribution area through residue, but also affect the content of soil cadmium and selenium in the surrounding area through water diffusion.
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Spatial Variation Characteristics and Influencing Factors of Black Soil Quality in Typical Water-Eroded Sloping Croplands

LI Linyuan, GAO Lei

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[Objective] To clarity the role of sedimentation and erosion in shaping the spatial pattern of soil quality in black soil slope croplands, this study focused on a typical water erosion area in Northeast China. [Methods]The research aimed to evaluate the spatial characteristics of soil quality at the slope scale by using soil attributes from 110 sample points. The assessment utilized the Soil Quality Index (SQI) based on a minimum dataset, while the effects of slope gradient, slope position, and soil depth were determined using Generalized Linear Models (GLMs). [Results] The findings are as follows: (1) Opposing patterns of soil nutrient content and spatial characteristics were observed between the surface and subsurface layers in sloping croplands. Most nutrient indicators exhibited significantly higher content in the tillage layer compared to the subsurface layer. However, the surface layer showed lower spatial heterogeneity and weaker correlation with related physicochemical indexes comparing with the subsurface layer (p＜0.05). (2) Erosion and sedimentation significantly influenced the spatial distribution characteristics of soil quality. The SQI was significantly lower in slopes with severe erosion compared to up-slope areas with weakly eroded regions and down-slope areas in depositional areas (p＜0.05). Compared with the upper position, the SQI of middle postion was 26.2% and 31.6% lower at surface and subsurface soil layers, respectively. Sedimentation did not improve the soil quality of severely eroded slope croplands, and there were no significant differences in SQI between down-slope and up-slope areas (p＞0.05). (3) Soil depth, slope position, and slope gradient emerged as key factors influencing the variability of SQI in slope croplands. The GLM results demonstrated that, for the same soil horizon, slope, aspect, and their interactions explained over 95-% variation in SQI. Among them, the explanatory degree of slope position was 68%, and that of slope gradient was 22%. Considering the factor of soil depth, the explanatory degrees of soil depth, slope position, and slope gradient on the variation of SQI in the range of 0-40 cm were 39%, 31%, and 10%, respectively..[Conclusion] In this study, the combined method of SQI and GLM was used to clarify the shaping role of erosion-sedimentation process in the spatial differentiation of black soil quality in sloping cropland, and the research results can provide technical support for the evaluation and management of the quality of eroded degraded black soil in typical water-eroded areas.
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Simulation of Soil Water Storage and Analysis of Influencing Factors in Weihe River Basin under Changing Environment

yukunxia

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With the intensified influence of climate change and human activities, the climate and underlying surface conditions of the basins have changed. Accurately simulating the process of soil moisture change and analyzing its influencing factors are of great significance for regional water resources management and vegetation construction. In this study, the Weihe River Basin in the Loess Plateau was taken as the research object. Based on the ABCD hydrological model, the EFAST method was used to analyze the parameter sensitivity of the model, and the constant parameter and time-varying parameter models were constructed. The runoff depth and soil water storage simulation accuracy of different parameter models were compared. The effects of climate change and vegetation restoration on soil water storage changes in the Weihe River Basin were discussed, and the dominant factors of soil water storage changes were clarified. The results show that: 1)The proportional parameter of soil water layer recharge groundwater c is the most sensitive, followed by the groundwater storage coefficient d, the upper limit parameter b of the sum of actual evapotranspiration and soil water storage, and the tendency parameter a of runoff before soil is completely saturated is the least sensitive. 2) Compared with the ABCD constant parameter model, the time-varying parameter model increased the values of NSE, KGE, and R2 of the runoff depth simulation results by 19%, 10%, and 19%, respectively, and the NSE, KGE, and R2 of the verification period increased by 7%, 7%, and 9%, respectively. The time-varying parameter model significantly improved the runoff depth simulation results. 3) The correlation between soil water storage and ERA5-Land 0~100cm soil water storage in Weihe River Basin based on time-varying parameter model simulation is the strongest, and the change process of the two agree well. 4) The degree of different influencing factors on the change of soil water storage in the Weihe River Basin from strong to weak is potential evapotranspiration > precipitation > NDVI. The research results provide scientific basis for water resources planning and management and vegetation construction in this area, and also provide reference for soil water storage research in other similar areas.
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Effects of vegetation restoration patterns on soil water-stable aggregates composition and their stability in the water level fluctuation zone of the Heilongtan Reservoir

BAI Qinfei, BAO Yuhai

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[Objective]In order to elucidate the effects of different vegetation restoration modes on soil water-stable aggregates and stability in the water level fluctuation zone(WLFZ).[Methods]The characteristics of soil water-stable aggregates and their stability indexes were determined and analyzed by the wet sieve method on the soil under artificially and naturally restored vegetation in the WLFZ in the hilly region of central Sichuan Basin.[Results]The content of >0.25 mm water-stable macroaggregates in WLFZ soils was 4.21% lower compared to unflooded area. The soil water stability macroaggregates content decreased by 12.27% under naturally restored vegetation and increased by 3.84% under artificially restored vegetation compared to unflooded area; With the rise of water elevations, the soil water stability macroaggregates content showed an increasing trend, the microaggregates content showed an overall decreasing trend, and the soil aggregate stability gradually increased with the rise of water elevations; The soil water-stable aggregates composition differed significantly (p < 0.05) among the different restoration modes, and the soil water-stable aggregates particle size increased overall under the artificially restored vegetation, in which the content of soil water-stable macroaggregates under the artificially restored vegetation (69.48%) was significantly higher than that of the natural restoration mode (43.20%); Decrease in soil water-stable aggregates stability in WLFZ with increasing flooding time, the values of R0.25, MWD, and GMD in the artificial recovery mode were greater than those in the natural recovery mode, and the values of D, K, and PAD were smaller than those in the natural recovery mode, Soil water-stable aggregates stability and soil erosion resistance were higher in the artificial restoration model than in the natural restoration model.[Conclusion]The soil aggregate stability of WLFZ decreased after inundation, but the artificial restoration mode can effectively improve the soil aggregate structure, and the results of the study can provide a scientific basis for the evaluation of soil structure stability and vegetation restoration of the WLFZ.
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Effects of vegetation community characteristics under different grazing intensities on soil aggregates in Xilamuren grassland

WANG Yiying, DONG Zhi

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[Objective] Vegetation community is an important factor affecting soil aggregates. However, the impact of changes in vegetation communities on soil aggregates under grazing pressure is still unclear. [Method] Taking Xilamuren Desert Steppe as the research object, the characteristics of vegetation community and soil aggregates under light grazing (LG), moderate grazing (MG), heavy grazing (HG) and no grazing (CK) and their relationship were analyzed by field investigation and indoor analysis. The effects of plant community changes on soil aggregates were revealed. [Results] (1) The number of plant community species increased with the increase of grazing intensity. The Shamnon-Wiener diversity index (H") and Simpson dominance index (D) of LG community were significantly lower than those of other grazing intensities (P<0.05). The aboveground biomass decreased with the increase of grazing intensity, and the aboveground biomass of HG was significantly lower than that of other grazing intensities (P<0.05). The underground biomass under different grazing intensities was significantly different, and the underground biomass of different soil layers was the highest in LG. (2) The change trend of mean weight diameter (MWD) and geometric mean diameter (GMD) was consistent with the content of macroaggregates. In 0-5 cm and 5-10 cm soil layers, it increased first, then decreased and then increased with the increase of grazing intensity (LG was the highest and MG was the lowest). (3) The community Shamnon-Wiener diversity index (H"), Pielous evenness index (J"), aboveground biomass, bulk density, organic carbon and total nitrogen content were significant factors affecting macroaggregate content, MWD and GMD (P<0.05). [Conclusion] The research results can provide theoretical support and scientific basis for rational grazing and ecological restoration in Xilamuren grassland.
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Response of Soil detachment capacity of Citrus Orchard Covered with Green Fertilizer to Concentrated Hydrodynamic Parameters

ZHANG Fengwei, WANG Xiaoyan

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[Objective]To explore the relationship between the soil detachment capacity of green manure cover and the hydraulic characteristics of concentrated water flow in typical sloping orange orchards in the Three Gorges Reservoir area, so as to provide data support for further clarifying the hydraulic characteristics of land upflow in typical sloping orange orchards during soil erosion. [Methods]Through the concentrated flow erosion test, the soil detachment capacity between bare slope and green manure (Trifolium repens, Poa annuaL, and Vicia sepium L) under the gradient hydrodynamic conditions of different slopes (10°~25°) and flow (18~126L/min) was analyzed, and the soil detachment capacity and water flow dynamic parameters (water flow shear force, water flow power), flow pattern parameters (Reynolds number, Freud number), and resistance parameters (Darcy-Weisbach resistance coefficient, Manning coefficient) and establish a corresponding mathematical model. [Results]The results showed that green manure mulching could significantly reduce soil soil detachment ability (P < 0.01). The soil detachment capacity of bare slope and green manure cover was positively correlated with the parameters of water flow dynamics and flow pattern (P < 0.05), and negatively correlated with the parameters of water flow resistance (P < 0.05). The prediction effect of water flow shear force on soil detachment capacity is better than that of water flow power. The Reynolds number predicts soil detachment capacity better than the Freud number. The prediction of the Darcy-Weisbach drag coefficient is better than that of the Manning coefficient. Overall, the shear force of water flow had the best effect in predicting soil detachment ability and had the highest accuracy (R2=0.957, NSE=0.963).
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Effects of Grazing Intensity on Soil Microbial Community Characteristics in Desert Steppe

ZHANG Mengmeng, XU Guoce

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Abstract： [Objective] Investigating the response mechanism of soil microbial communities to changes in grazing intensity can provide scientific theoretical and technical support for ecological protection and restoration of desert steppe. [Methods] Taking the desert steppe in Inner Mongolia as the research object, we studied the effects of different grazing intensities (no grazing, light grazing, medium grazing, high grazing) on soil physicochemical properties and the composition and diversity of soil microbial communities at different soil depths (0-20 cm and 20-40 cm), The interactions between soil physicochemical properties and soil microbial communities were analyzed. [Results] The results showed that, compared to no grazing, medium grazing significantly (p<0.05) reduced the soil total nitrogen (TN) content (by 17.99%) and soil organic carbon (TOC) content (by 19.23%) at 0-20cm depth. The maximum value of soil bulk density (SBD) appeared under high grazing conditions. The soil physicochemical properties at 20-40cm depth showed no differences (p>0.05) under different grazing intensities. In addition, grazing decreased the abundance and diversity of bacterial communities at 20-40cm depth, while increased the abundance and diversity of bacteria communities at 20-40cm depth. Under light and moderate grazing conditions, the abundance and diversity of soil fungal communities at 0-20cm depth increased, with no significant effect (p>0.05) on the abundance and diversity of soil fungal communities at 20—40cm depth. [Conclusion] Mantel tests showed that total nitrogen of desert steppe soil is the primary factor influencing the change of desert steppe soil bacterial abundance with grazing intensity. The research results contribute to understanding the ecological sensitivity of soil microbes and offer scientific guidance for achieving sustainable management in desert steppe ecosystems.
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Optimization of Water And Nitrogen Regimes Based on AquaCrop Model for Drip Irrigation Cotton under Nitrogen-reducing Conditions in The Northern Border Region

Wang SiJia, WANG Chunxia

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[Objective] To optimize the nitrogen application system for drip irrigation cotton under reduced nitrogen fertilization. [Methods] Sampling field experiment and AquaCrop model were combined to carry out the study. [The results showed that the highest cotton yields of 5.496×103kg·hm2 and 5.126×103kg·hm2 were obtained from W2Nck (10% reduction in irrigation with normal N application) or W1Nck (10% increase in irrigation with normal N application) treatments, and the highest yields of 5.496 t·hm2 and 5.126 t·hm2 were obtained from W2N1 (10% reduction in irrigation with 30% reduction in N application) or W1N1 (10% increase in irrigation with 30% reduction in N application). 10% paired with 30% reduction in N application) treatments had the lowest cotton yields of 3.933×103kg·hm2 and 3.625×103kg·hm2, and the combined effect of water and nitrogen stresses negatively affected cotton yields; compared with single measures, increasing or decreasing the irrigation volume at normal nitrogen application levels could result in a yield-increasing effect; appropriately decreasing the irrigation volume or increasing the nitrogen application was more conducive to increasing the water use efficiency and reduce nitrogen residue in the soil. The AquaCrop model was calibrated with two years of experimental data, and the calibrated parameters were used to simulate cotton yield and water and nitrogen utilization under 300-600 mm irrigation quota under nitrogen reduction conditions 0.94; biomass evaluation index R2>0.947, NRMSE<40.58, ENS>0.72, yield evaluation index R2>0.91, NRMSE<4.29%, ENS>0.85; and water use efficiency evaluation index R2>0.87, NRMSE<4.22%, ENS>0.81, which indicated that the AquaCrop model had a better effect on the water-nitrogen treatment in cotton fields has good applicability. [Conclusion] Model simulation of 240 nitrogen and irrigation combinations, combined with the analysis of yield, water use efficiency and nitrogen bias productivity indexes, the combination of 10% nitrogen reduction and 360 mm irrigation quota can be used as a preferred solution to achieve stable yield and reduce economic costs under efficient water and nitrogen utilization. The optimization of cotton irrigation and nitrogen application system under the premise of stable yield of cotton under drip irrigation under membrane in Northern Xinjiang can be used as a reference basis for improving water and nitrogen utilization efficiency during cotton cultivation in arid areas.
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Effects of aeration on tomato growth and soil enzyme activity under the condition of topdressing fertilizer reduction

Li Jingang, Chen Jing

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[Objective]To explore the effects of aeration on crop growth characteristics and soil environmental characteristics in rootzone under reduced topdressing conditions. [Methods]the present paper takes the field cultivated tomato in Yinbei irrigation area of Ningxia as the research object. Four groups of micro-nano gas aeration ratios (0%, 5%, 10%, 15%) and three topdressing (urea-triple superphosphate-potassium sulfate) levels (180-400-480 kg/hm2, 135-300-360 kg/hm2, 90-200-240 kg/hm2) were set up for the two-year field experiment conducted in 2019 and 2020. [Results]The results showed that with the same topdressing level, the dry matter and nutritional elements (N, P, K) accumulation in the plant increased with the increase of aeration ratio, and increasing the aeration ratio was beneficial to the accumulation of phosphorus in roots during flowering-fruit setting period and the potassium accumulation at fruit expansion stage. With the same topdressing level, the tomato yield increased by 14 %-44.2 % as the aeration ratio increased by 5%-15%. With the same aeration ratio, the tomato yield increased by 0.4%-9.1% as the topdressing level was appropriately reduced (-25%) compared with the traditional fertilization. The increase of the aeration ratio and topdressing level was beneficial to increase the soil enzymes (catalase, alkaline phosphatase and urease) activity significantly during the flowering-fruit setting period and fruit enlargement period of tomato. With the same topdressing level, increasing the aeration ratio by 5%-15% corresponded to an increase of the soil enzyme activity by 27.5%-122.9%. [Conclusion]It was suggested that, to promote tomato plant growth, stabilize tomato yield and improve the soil enzymes activity in the Yinbei irrigation district, the suitable topdressing level of “urea-triple superphosphate-potassium” was 135-300-360 kg/hm2 (25% lower than the traditional topdressing amount), and the suitable micro-nano aeration ratio was 10%.
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Accuracy assessment of multi-source land use products in the loess hilly and gully region

CHEN Le, WEI Wei

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Evaluating the accuracy of multi-source land use products is essential for obtaining reliable surface information, supporting land planning and management, and promoting regional ecological protection and high-quality development. However, the capability of existing land use products to accurately depict the surface cover characteristics in complex terrains or fragmented habitats, such as the loess plateau hilly and gully regions, remains uncertain. Taking the Guanchuan River Basin, a secondary tributary of the Yellow River, as an example, this study assessed the accuracy of six land use products with spatial resolutions of 10 m and 30 m (WorldCover 10 m, ESRI 10m, GLC_FCS30-2020, GlobleLand30, CNLUCC, and CLCD) in the loess hilly and gully region using high-precision GCLUCC land use data. This GCLUCC data, with an overall accuracy exceeding 95%, was derived from GF-2 (0.8m), DEM (5m), and 6400 field sampling points, employing the object-oriented method and manual visual interpretation. The evaluation results showed that (i) In terms of classification characteristics, most products could extract main land categories, yet significant differences existed in extraction efficiency and accuracy, especially regarding the spatial distribution of terraced fields, forest lands, and construction lands; (ii) For area consistency, there were significant discrepancies in land category areas between various products and GCLUCC. For instance, the grassland area in some products was more than twice that of GCLUCC, while forest and water areas accounted for only 0.13%-12.11% and 1.03%-5.86% of GCLUCC, respectively; (iii) In terms of overall accuracy, GlobleLand30 and WorldCover 10m demonstrated relatively higher accuracy, reaching 58.21% and 50.19%, respectively. The accuracy of CLCD and CNLUCC was comparatively lower, with notable classification confusion between forests and grasslands, terraced fields and grasslands, and construction lands and terraced fields; (iv) Significant spatial discrepancies existed between various products and the actual ground surface, particularly in accurately classifying forests, shrubs, bare land, and water bodies. In conclusion, current land use products still face notable challenges in precisely describing surface cover characteristics in the loess plateau hilly and gully regions. Future product development should place greater emphasis on topographical and geographical features and strengthen the recognition of specific land use types like forests, shrubs, bare land, and water bodies to enhance data accuracy and decision-making reliability.
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Impacts of Rainfall Characteristics and Vegetation Cover Patterns on Hillslope Runoff and Sediment Yields in the Three Gorges Reservoir Area

SONG Minxin, TANG Qiang

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[Objectives] The Three Gorges Reservoir area is an important ecological barrier in the upper reaches of the Yangtze River and a national key area for soil and water erosion control. With the implementation of major ecological restoration projects, the effectiveness of vegetation construction has been obvious, but the water regulation and soil conservation effects of restored vegetation lack in situ observation and quantitative research. The prominent contradiction between man and land and the development of rural industries have put forward new demands for the optimal utilization of understory land resources, and their impact on the water conservation and soil erosion control functions is not yet clear. [Methods] Taking a typical fallow forest in the Three Gorges Reservoir Area as the research object, four runoff plots with full-slope herbaceous cover (QF), upper-slope bare ground + lower-slope herbaceous cover (XF), equidistant herbaceous strip cover (TF), and full-slope herbless coverage (WF), were set up to carry out field observation of slope runoff and sand production in 24 erosive rainfall events and to identify the effects of erosive rainfall and vegetation cover patterns on hillslope runoff and sediment yields. [Results] The results show that:(1) The 24 erosive rainfall events were classified into three categories, including A-type (small rainfall, heavy rainfall intensity, and short duration), B-type (large rainfall, heavy rainfall intensity, and short duration), and C-type (small rainfall, light rainfall intensity, and long duration). A-type is the rain type with the highest frequency, with a frequency of 45.83%. The cumulative rainfall of B-type is the largest, accounting for 63.44% of the total rainfall. (2) The cumulative runoff depth and cumulative erosion volume of the four vegetation cover patterns generally showed QF
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Analysis on The Spatial and Temporal Changes and Driving Mechanism of Cultivated Land Conversion in Central Yunnan Urban Agglomeration From 1990 to 2020

yangyuqian, pengshuangyun

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[Objective]By analyzing the evolution path, spatiotemporal variation characteristics, and driving mechanisms of farmland non agriculturalization in the central Yunnan urban agglomeration over the past 30 years, theoretical basis is provided for the protection and precise management of farmland resources in the central Yunnan urban agglomeration.[Methods] Based on the land use data and statistical yearbook data of the Central Yunnan urban agglomeration, the paper uses methods such as gravity displacement model, change trajectory model, spatial autocorrelation analysis, and principal component analysis to reveal the process and spatial distribution characteristics of farmland conversion to non-agricultural uses in the Central Yunnan urban agglomeration from 1990 to 2020, as well as the main driving factors.[Results] The results indicate that:(1) From a temporal perspective, the non agricultural area of cultivated land in the central Yunnan urban agglomeration has shown a fluctuating downward trend, with the most drastic changes affected by policies, economy, and urbanization around 2000. From a spatial perspective, the non-agricultural conversion of cultivated land is concentrated in the central, eastern, southeastern, and northeastern regions of the central Yunnan urban agglomeration.(2) Over the past three decades, farmland converted to non-agricultural land in the Central Yunnan Urban Agglomeration has tended to be balanced in spatial distribution, with smaller differences in farmland conversion between regions and a stable spatial pattern overall, generally exhibiting a trend of migration to the southwestern region.(3) The main destinations for farmland converted to non-agricultural land in the central Yunnan urban agglomeration are forestland and grassland, with a small portion converted into construction land, mainly in the central, northern, and southeastern parts as well as in some local areas of the northwest.(4) There is a significant spatial clustering effect in the non-agricultural transformation of cultivated land in the central Yunnan urban agglomeration, mainly characterized by high high clustering and low low clustering. High high clustering is mainly distributed in the central, northern, and southeastern regions, while low low clustering is mainly distributed in the northwest, western, and southwestern regions.(5) The non agriculturalization of cultivated land in the central Yunnan urban agglomeration is influenced by both socio-economic and natural conditions. The state-owned fixed asset investment, agricultural population, and urbanization rate are the main driving factors for the non-agricultural expansion of farmland in the social economy, while natural factors such as annual precipitation and temperature play a crucial role in the spatial distribution and expansion process of non-agricultural farmland.[Conclusion] The results have revealed the spatiotemporal change characteristics, evolution path, and driving mechanisms of farmland converted to non-agricultural land in the central Yunnan urban agglomeration over the past 30 years. The research results reveal the spatial and temporal characteristics, evolution path, and driving mechanism of cultivated land conversion in the Central Yunnan Urban Agglomeration over the past 30 years. It plays an important role in rational utilization and protection of arable land resources and ensuring food security in Yunnan Province, and to a certain extent, it can provide decision-making reference for the protection and optimization of arable land layout in the Central Yunnan Urban Agglomeration.
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Analysis of Hydrological Characteristics and Influencing Factors of Typical Lakes in the Qinghai Tibet Plateau from 1985 to 2021

zhangjiaqi, zhanghuilan

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The lakes of the Tibetan Plateau are important indicators of climate change, and their expansion or contraction also has an important impact on the natural environment of the Tibetan Plateau. Three typical lakes (Qinghai Lake, Yangzhuoyong Lake, and Ulan Ula Lake) located in different climatic sub-zones of the Qinghai-Tibet Plateau were selected and remote sensing monitoring methods were used to study the temporal and spatial variation of the hydrological characteristics of the three typical lakes from 1985 to 2021, reveal the role of key climatic factors, and further explore the influence of glaciers and frozen soil on typical lakes. The results show that the area and water level of Qinghai Lake show a significant upward trend during the study period. The area increased by 238.68km2, the water level increased by 1.32m, and the space showed a trend of expansion in the east-west direction; the area of Yangzhuoyong Lake showed a trend of first fluctuating and then decreasing, decreasing by 16.316km2 and 3.25 meters respectively, and the overall spatial situation showed a shrinking trend from all sides to the center; the area and water level of Ulan Ula Lake showed a significant upward trend, increasing by 125.575km2 and 8.12 meters respectively, and the expansion area was mainly concentrated in the south. The analysis of key climatic factors showed that precipitation change was the key factor affecting the area change of Qinghai Lake and Yanghu Lake, and the area change and precipitation lagged. The main reason for the rise in the water level of Ulan Ula Lake is the seasonal thawing of the frozen soil caused by the increase in temperature. Exploring the changes of lake area on the Qinghai-Tibet Plateau is of great guiding significance for in-depth study of global climate change and surface water resources assessment.
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Effects of organic fertilizers and other nitrogen replacements for chemical fertilizers on growth, yield and water and fertilizer use efficiency of spring maize

CHEN Mengru, WANG Xiukang

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To investigate the effects of organic fertilizers and other nitrogen replacements for chemical fertilizers under different nitrogen application rates on the growth, yield and water-fertilizer use efficiency of spring maize in the dry zone of northern Shaanxi, multiple regression analysis and three-dimensional fitting models were used to establishing an optimal nitrogen management model for spring maize cultivation in northern Shaanxi. In this experiment, three nitrogen application levels were (N1: 240 kg/hm2, N2: 180 kg/hm2 and N3: 120 kg/hm2) and five organic fertilizers and other nitrogen replacements for chemical fertilizers ratios were (R0: 100% fertilizer nitrogen, R12.5: 12.5% organic fertilizer nitrogen + 87.5% chemical fertilizer nitrogen, R25: 25% organic fertilizer nitrogen + 75% chemical fertilizer nitrogen, R37.5: 37.5% organic fertilizer N + 62.5% chemical fertilizer N and R50: 50% organic fertilizer N + 50% chemical fertilizer N), a total of 15 treatments. During the main reproductive period of spring maize, spring maize growth and yield and yield components were measured, and water consumption (ET), water use efficiency (WUE), nitrogen fertilizer partial productivity (NPFP) and economic benefits were calculated. The results showed that the ????????????? Logistic function had a high fit for dry matter accumulation in spring maize, the R12.5 treatment delayed the start, the end and the appearance of the maximum value of the period of rapid dry matter accumulation, and the N2 treatment enhanced the maximum daily growth rate of dry matter accumulation. Nitrogen application and replacement ratio significantly affected dry matter accumulation, yield and components, ET, NPFP and economic efficiency of spring maize (P<0.05), and the interaction significantly affected ear length, ear coarse and ET (P<0.05). The average dry matter accumulation, yield, ET, and net income of N2 treatment were higher than that of N1 and N3 treatment 5.58 and 15.80%, 4.25% and 16.76%, 4.96% and 3.41%, 8.76% and 29.42%, respectively. R25 treatment significantly enhanced dry matter accumulation, yield and components, ET, WUE, NPFP, net income and input/output. WUE continued to increase with increasing N application while NPFP continued to decrease. Treatment N2R25 had the highest dry matter accumulation and ET, and treatment N2R37.5 had the highest yield, net income and input/output. Spring maize yield was significantly and positively correlated with dry matter accumulation, ET, WUE, net income and input/output. Taking into account the dry matter accumulation, yield, WUE and net income of spring maize, the nitrogen fertilizer management was optimized, and the nitrogen application rate and replacement ratio range were 160~230 kg/hm2 and 8~38%, respectively, spring maize dry matter accumulation, yield, WUE and net income can all reach more than 95% of the optimal value while the NPFP under the this combined treatment was 66.68 ~ 93.98 kg/kg.
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The impacts of extreme climate events on vegetation dynamics in the Qinling-Daba Mountains

CHEN Chaonan, ZHU Wenbo

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Global warming has contributed to extreme climate events that have had a significant impact on vege-tation. However, the spatio-temporal changes in extreme climate and its influence on vegetation remain unclear in the Qinling-Daba Mountains (QBMs). Based on satellite-derived Normalized Difference Vegetation Index (NDVI) and meteorological datasets, we analyzed the spatio-temporal variations of the NDVI and its response to 19 extreme climate indices in the QBMs. Geographic detector was used to identify the contribution rate of extreme climate indices and their influence on the NDVI. The results indicated that the NDVI significantly increased in the majority of the QBMs (80.34%) and decreased in only a few regions (1.09%) from 2000 to 2020. Noticeable warming was observed in the QBMs from 1960 to 2020, with the temperature increasing more at night than during the day, and regions with a larger change in the extreme temperature events were mostly found in the Western Qinling Mountains (WQMs). During the study period, extreme precipitation events showed weak changes, extreme precipitation intensity increased in the southwestern QBMs, while in the eastern QBMs, extreme precipitation intensity decreased but extreme precipitation frequency increased. Additionally, significant spatial variations were observed in the NDVI reaction to extreme climate indices in the QBMs. The correlations between extreme precipitation indices and the NDVI were higher than those between extreme temperature indices in the WQMs, whereas inverse relationship were observed in the Qinling Mountains (QMs) and Daba Mountains (BMs). We also found that the influence of extreme climate indices on NDVI was not independent, and the interaction between the extreme climate indices amplified the influence of a single index on NDVI in both double-factor or nonlinear ways. The paper can establish scientific evidence for the protection and restoration of vegetation in the QBMs in response to global climate change.
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Multi-scenario Simulation and Water Resource Effects of Integrated Utilization of Saline-alkali Land in Western Jilin Province

liwenbo

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[Objective] The integrated engagement of saline-alkali land remains a quintessential stratagem to enhance grain yield whilst embracing the principle of Greater Food. The current simplistic reclamation approaches and the intensive water demands, however, call for a thorough investigation of diversified management strategies and interventions that take into account the impact on water resources.[Methods] The study selected the western part of Jilin Province as the study area and adopted the FLUS model to forecast the utilization patterns of saline-alkali land resources until 2030 under four scenarios: natural progression, grain security, integration of grain and forage production, and ecological protection. The InVEST model is then applied to evaluate the variations in water yield across these scenarios.[Results] (1)From 2000 to 2020, 1 540.18 km2 of saline-alkali land in the study area was put to use, predominantly restored to grassland or reclaimed as cultivated land, with a substantial risk of secondary salinization in drylands. (2)Under all scenarios, the reclamation of saline-alkali land for agriculture prevails. In the grain security scenario, the paddy fields and dry lands account for 67.48% and 4.23%, respectively. When compared with the natural progression scenario, the grassland area is set to expand by 60.76 km2 in the integration of grain and forage production scenario, and ecological land will increase substantially under the ecological protection scenario. (3)By 2030, water yield is projected to decrease in all four scenarios relative to the baseline period, with the ecological protection scenario facing the steepest reduction at 3.71×108 m3. Conversely, the integration of grain and forage scenario offers a well-balanced solution, ensuring the output of crops and forage while easing the water pressures initiated by the management of saline-alkali land.[Conclusion] Utilization of saline-alkali land in the Songnen Plain requires a balanced and strategic approach that supports both grain and forage production. Efforts should be made on maintaining the equilibrium between the supply of agricultural and fodder resources whilst ensuring food and ecological security. The overarching goal is to regulate the ecological restoration of our territorial space and utilization of degraded lands following the concept of Greater Food.
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Regulatory mechanisms of nitrogen and phosphorus transformation and maize growth in soils of the black soil zone: based on field experiments

gongpinxiang, fuqiang

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[Objective] To investigate the effects of different tillage patterns and biochar application on soil nitrogen and phosphorus transformation and maize growth and development in farmland in the black soil area. [Methods] In this paper, 10 different treatments were set up through a field experiment: deep tillage + 0t/hm2^{biochar (DCK), deep tilla}ge + 3t/hm2^{biochar (D}3), deep tillage + 6t/hm2^{biochar (}D6), deep tillage + 9t/hm2^{biochar (}D9), deep tillage + 12t/hm2^{biochar (}D12), shallow tillage + 0kg/mu biochar (SCK), shallow tillage + 3t/hm2^{biochar (}S3), shallow tillage + 6t/hm2^{biochar (}S6), shallow tillage + 9t/hm2^{biochar (}S9), and shallow tillage + 12t/hm2^{biochar (}S12), to investigate the combined effects of different tillage patterns and biochar application on soil nitrogen and phosphorus fractions, enzyme activities, and physiological characteristics of maize. [Results] The results of the study showed that: (1) deep tillage and shallow tillage in combination with biochar application could effectively improve soil structure, increase the geometric mean diameter of agglomerates and reduce the percentage of damage, and the deep tillage treatment was more effective than the shallow tillage treatment; (2) the application of biochar improved soil nitrogen-phosphorus fractions, urease activity, and alkaline phosphatase activity, and the effect of applying biochar at the rate of 9t/hm² was the best, which was more pronounced in the deep tillage treatment; (3) deep tillage The application of biochar up to 9t/hm2^{under d}eep plowing treatment increased the total nitrogen and phosphorus contents and glutamine synthetase activity of leaves, and decreased the acid phosphatase activity; (4) the yield of corn under deep plowing condition with the application of 9t/hm2^ofbiochar was as high as 17.37t/hm2^{, which was increased by}28.9% compared with that of the CK group. [Conclusion] The deep-tillage treatment and application of 9t/hm² biochar provided a reference for the nutrient environment and crop growth in agricultural fields in the black soil area.
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Spatiotemporal distribution and hot spots analysis of ecosystem services in Beijing and Tianjin sandstorm source region

Chang Jin Yu, Wu Zhi-tao’

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In order to assess the ecological benefits and ecological impacts after the implementation of the ecological project in the Beijing-Tianjin wind and sand source area, based on the remote sensing, meteorological, soil, and land use data of the Beijing-Tianjin wind and sand source area from 2000-2017, the CASA (Carnegie-Ames-Stanford approach) model, the InVEST ( Integrated valuation of ecosystem services and trade offs) model, RWEQ (Revised wind erosion equation) model, and RUSLE (Revised Universal Soil Loss Equation) model, respectively. The water yield, soil conservation, carbon sequestration and wind and sand services were estimated respectively, and the Getis-Ord Gi* statistical index method was used to identify the ecosystem services hot and cold spots in the Beijing-Tianjin wind and sand source area. The results showed that (1) each ecosystem service function showed an increasing trend from 2000 to 2017, and the high value areas of the four ecosystem service functions were concentrated in the southeast of the study area, and the low value areas were concentrated in the northwest of the study area. (2) All four ecosystem services showed a significant hotspot area increase in the Ordos Plateau sandy land management area in the southwestern part of the Beijing-Tianjin wind and sand source from 2000 to 2017; the area of hotspot for carbon sequestration services increased significantly, of which the sandy land management area in the Hunshandak-Khorqin sandy area and the hilly mountainous area of the Damshang Plateau and northern North China The hotspot area of water production service has not changed significantly, and the hotspot area is mainly concentrated in the southern part of the study area in the Damshang Plateau and the hilly and mountainous water conservation management area in northern China, and the distribution of the hotspot area is more scattered; the coldspot area of windbreak and sand fixation service has increased in area; the area of the coldspot area of soil conservation service has a small percentage and not much change, and the regional capacity of soil conservation and supply is relatively average. The regional soil conservation supply capacity is relatively average. (3) The results of multiple ecosystem services show that the southeastern region of the study area is able to provide two or more high-value ecosystem service functions, and belongs to the key ecosystem service function supply area, accounting for about 15.5% of the whole study area. (4) The four ecosystem service hotspot areas of forest land accounted for a relatively high percentage of the area from 2000 to 2017, and the hotspot areas of carbon sequestration service functions of grassland and forest land increased significantly, and forest land can provide a high level of integrated ecosystem service functions. The implementation of the Beijing-Tianjin Wind and Sand Source Control Project has improved the overall ecosystem service function in the region, and the results of the study can provide scientific data for assessing the effectiveness of the restoration of the Beijing-Tianjin Wind and Sand Source Control Project, and ultimately realize the sustainable development of the ecological environment in the Beijing-Tianjin region.
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Soil microbial biomass and ecological stoichiometric characteristics of typical land use types in loess hilly region

husile, dongliguo

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[Objective]To investigate the effects of the typical ecological management model of "upward retreat and downward push" on soil-microbial C, N and P and their ecological stoichiometric ratios in loess hilly areas.[Methods] In this study, typical land use types (artificial forest land, terrace, and Chuanland) in the loess hilly area of Ningxia were selected to study the response of soil-microbial C, N and P contents to land use changes and to analyze the ecological stoichiometric ratios, microbial entropy (qMBC, qMBN, and qMBP), and stoichiometric imbalances (C:Nimb, C:Pimb, and N:Pimb) among the Relationship.[Results] (1) Under the three typical land use types, SOC, C:P and N:P in artificial forest land were higher than those in terraced and Chuanland, while TP content in agricultural land (terraced and Chuanland) was higher than that in artificial forest land. (2) The contents of soil microbial biomass C, N and P ranged from 51.56 to 133.19, 7.97 to 21.98, and 4.63 to 12.81 mg/kg, respectively. Among them, soil microbial biomass C, N and P were in the order of artificial forest land > terrace land > Chuanland. The ratio of microbial biomass C, N, P, C:Nimb, C:Pimb, N:Pimb, had certain characteristics of internal stability, and had no significant difference among different land use types. (3) The three typical land use types have significant effects on microbial entropy, with the qMBC ranking as terraced land > artificial forest land > Chuanland, while the qMBN and qMBP ranking as artificial forest land > terrace land > Chuanland. Combined with RDA analysis, it was concluded that microbial biomass C:P (R2=0.75, p<0.01) and C:Pimb (R2=0.74, p<0.01) were the key factors affecting the change of qMB.[Conclusion] In summary, the typical ecological management mode of "upward retreat and downward push" caused significant changes in soil C, P and microbial C, N and P contents, and the soil-microbial C, N and P and their stoichiometric ratios were mainly influenced by phosphorus under the typical land-use types.
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Effects of Soil Organic Carbon and Moisture on Different Vegetation Restoration Types in the Mu Us Sandy Land

WANG Defu, DENG Lei

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Vegetation restoration is one of the most effective measures to improve the fragile ecological environment in arid regions. Extensive vegetation restoration in the Mu Us Sandy Land has significantly influenced the soil carbon and water cycling within the area. Investigating the responses of soil organic carbon and moisture content to vegetation restoration holds crucial significance for the sustainable development of the ecological system in this region. This study focused on the natural restoration grassland and different vegetation restoration types, including Artemisia desertorum, Salix psammophila, A. desertorum-S. psammophila mixed(shrub-shrub mixed), Pinus sylvestris, S. psammophila-P. sylvestris mixed(tree-shrub mixed), in the Mu Us Sandy Land. A bare sandy area was used as the control. The aim was to investigate the effects of different vegetation restoration types on soil carbon and moisture content within the 0-5 m soil profile. The results showed that:(1)Vegetation restoration increased, with S. psammophila-P. sylvestris mixed, P. sylvestris, Grassland, A. desertorum-S. psammophila mixed, A. desertorum-S. psammophila mixed, and A. desertorum showing decreasing trends, with significant accumulation effects observed within the 0-20 cm soil depth. As soil depth increased, the organic carbon content of all vegetation types gradually decreased. Within the depth range of 80-220 cm, A. desertorum, S. psammophila, and A. desertorum-S. psammophila mixed exhibited carbon loss.(2)Different vegetation restoration types showed varying degrees of soil moisture deficit in deep soil layers, primarily concentrated at 1-3 m, with S. psammophila-P. sylvestris mixed showing the most severe deficit, followed by P. sylvestris, A. desertorum-S. psammophila, S. psammophila, Grassland, A. desertorum.(3)Root were identified as the main factors influencing soil organic carbon content and moisture consumption. Soil organic carbon content exhibited a negative correlation with soil moisture within the 0-5 m soil depth range. Vegetation carbon storage was achieved at the expense of consuming deep soil moisture, with S. psammophila-P. sylvestris mixed exhibiting the least water consumption per unit of fixed carbon. The study suggests that S. psammophila-P. sylvestris mixed exhibits favorable effects in vegetation restoration from the perspective of soil carbon retention and water retention in the Mu Us Sandy Land.
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Estimation and Prediction of Water Conservation Capacity in Shaanxi Province Based on InVEST-PLUS Model

zhoupingping, songxiaoyan

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The InVEST model and PLUS model were coupled to calculate the water conservation amount in Shaanxi Province from 2000 to 2020 and predict the water conservation amount under land use changes in the future in 2030. The results indicate that the average water conservation amount in Shaanxi Province from 2000 to 2020 was 132.25mm, with a spatial distribution characteristic of gradually increasing water conservation amount from north to south.From the perspective of vegetation types,forest land is the main body of water conservation in Shaanxi Province. The average annual water conservation amount is 199.55×108m3. From the administrative region, Ankang City (308.96mm) has the largest water conservation amount. The total amount of water source conservation in 2030 is 285.16×108m3,8.68×108m3 less than in 2020..
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Modeling and Analysis of Hydraulic Erosion in Slope Farmland Using Gradient Lifting Tree Model

litongliang

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Based on the Gradient Lifting Tree Model (GBDT), a hydrological experimental dataset from the Zizhou Runoff Experimental Station in the Yellow River Basin was used to model and analyze hydraulic erosion on sloping farmland. The results showed that: 1. The coefficient of variation for secondary rainfall erosion (0-122.72 t/km2), runoff depth (0.02-17.20 mm), rainfall duration (2-1410 min), and average rainfall intensity (0.02-4.63mm) in the dataset are all greater than 1, indicating high variability. Most variables exhibit a right-skewed distribution.2. When dividing the dataset into training and testing sets, the model''s accuracy in predicting soil erosion during secondary rainfall (R2=0.81) is slightly higher than that of the runoff depth prediction model (R2=0.80). However, the number of layers in the secondary erosion model (8 layers) exceeds that of the runoff depth prediction model (5 layers), suggesting a more complex erosion mechanism compared to the runoff mechanism. 3. The prediction results are not ideal for small secondary erosion amounts and runoff depths due to limitations in feature extraction. Future research should explore additional combinations of independent variables to identify more relevant factors. 4. The main influencing variables differ between the erosion runoff and sediment production processes. Precipitation characteristics play a major role in runoff production, while erosion sediment production is mainly influenced by the combined effects of precipitation and terrain-related independent variables. This study, being data-driven, provides insights into the erosion mechanism of slope farmland in the Loess Plateau and serves as a scientific basis for sustainable regional development.
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The Impact of Flexible Vegetation on Surface Runoff Hydraulic Characteristics and Erosion

CAI Zekang

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There is limited research on the influence of near-surface coverage of flexible vegetation on reducing runoff and erosion yields, as well as on regulating the hydraulic characteristics of surface runoff. Based on the principles of fluid mechanics and hydraulics, this study conducted indoor drainage experiments under five coverage levels, five slopes, and three flow rate combinations. The erosion patterns and hydrodynamic characteristics under flexible vegetation cover conditions were systematically investigated. The results indicate: (1) The distribution of erosion volume initially rises and then falls with increasing slope, with flow rate having a more significant impact on the erosion process at higher slopes. (2) As the coverage of flexible vegetation increases, erosion volume decreases initially and then increases, with 50% coverage as the turning point. (3) The average flow velocity (v) decreases with increasing coverage, and the decreasing trend becomes less steep as coverage increases. The variation trend of the Froude number (Fr) is similar to that of the average flow velocity. The resistance coefficient (f) is linearly correlated with coverage, and with increasing slope, the value of the resistance coefficient gradually decreases. Reynolds number (Re) is more sensitive to soil erosion than Fr, v, and f. (4) With increasing vegetation coverage, morphological shear force increases (particle shear force decreases), and morphological shear force plays a decisive role in the variation of total shear stress, which is positively correlated with vegetation coverage. This study lays a theoretical foundation for understanding the erosion patterns of vegetated slopes, and promotes the extension of open channel hydraulics theory in slope surface flow.
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Relationship between soil infiltration and crust under continuous and intermittent precipitation

Liu Zhiqiang, Li Guanglu

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The Loess Plateau, one of the ecologically vulnerable regions in China, experiences concentrated and intense precipitation, characterized by significant topographical variations and fragmented landscapes. With sparse vegetation cover, the area faces prominent issues of soil erosion. Soil crusts, characterized by high bulk density and low porosity, are a common soil structural feature in the Loess Plateau formed under the impact of precipitation, runoff compaction, or irrigation. The formation of soil crusts severely affects water infiltration and runoff generation, hindering efficient water resource utilization and impeding the conversion between surface water and groundwater. To investigate the relationship between soil crust and infiltration performance under continuous and intermittent precipitation conditions, three typical cultivated soils from the Loess Plateau were selected. Indoor simulated precipitation experiments were conducted, utilizing three precipitation drop diameters (2.67 mm, 3.39 mm, and 4.05 mm), continuous precipitation durations of 10, 20, and 30 minutes, and 1-2 episodes of intermittent precipitation. The study analyzed the relationship between crust strength, cohesion, and soil infiltration performance under different precipitation conditions. Furthermore, variations in the content of soil aggregates of different particle sizes in the topsoil under different precipitation conditions were examined, along with their influence on infiltration performance. Finally, using grey relational analysis, the study summarized the weights of various factors affecting infiltration performance and ranked their significance. The results revealed that infiltration performance decreased with the increase in continuous precipitation duration and the number of intermittent precipitation episodes. Under equivalent precipitation duration and intensity, intermittent precipitation exhibited a greater reduction effect on infiltration compared to continuous precipitation. Crust strength and cohesion increased with prolonged continuous precipitation duration and a higher number of intermittent precipitation episodes. Infiltration performance of chestnut soil and black loam soil exhibited a significant linear correlation with crust strength and cohesion (P<0.05). As the duration of continuous precipitation and the number of intermittent precipitation episodes increased, the generated crust strength and cohesion also increased, consequently resulting in a greater reduction in infiltration efficiency. In contrast, the infiltration performance of sandy loam soil demonstrated a nonlinear correlation with crust strength and cohesion (P<0.05). Experimental results indicated that with an increase in the number of intermittent precipitation episodes, soil aggregates became more fragmented. Moreover, as precipitation intensity increased with precipitation duration, the efficiency of degrading large aggregates (>0.25 mm) into smaller aggregates (<0.25 mm) also increased. Comparative analysis of the changes in Mean Weight Diameter (MWD) and Geometric Mean Diameter (GMD) of soil crusts under different precipitation conditions revealed that a smaller MWD and GMD corresponded to poorer infiltration performance and a greater reduction in infiltration efficiency. Grey relational analysis further emphasized the significance of MWD and GMD as the most influential factors affecting infiltration performance, with higher correlation observed for intermittent precipitation compared to continuous precipitation. This study provides valuable insights for mitigating soil erosion and promoting effective water resource management in the Loess Plateau.
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Multi-scenario prediction of land use change and carbon stock in Shaanxi Province based on SD-PLUS coupled model

liqian, wangchengjun

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Studies have shown that different land use modes have significant effects on regional ecosystem carbon stocks. In this paper, using the SD-PLUS coupled model and the coupled shared socio-economic route and representative concentration route (SSP-RCP) scenario proposed by the International Coupled Model Comparison Program Phase 6 (CMIP6), the land use changes in Shaanxi Province in 2030 were projected, and then the different future scenarios simulated by the InVEST model were used to predict the Shaanxi Province"s carbon storage and its spatial distribution under different future scenarios simulated by the InVEST model. The results show that;(1)The SD model constructed was tested historically, and its error was less than 5%, and the Kappa index of land use in 2020 simulated by the PLUS model was 0.86, and the accuracy and reliability of the model generally met the requirements;(2) Under the three scenarios, the area of future construction land increases, and the scenarios with the lowest to highest growth rates are: SSP126, SSP245, SSP585; under all scenarios, the area of forest land increases, and the area of watersheds remains stable; the area of grassland has a small increase under the SSP126 scenario, and decreases in other scenarios; and the area of arable land decreases in all three scenarios;(3) Carbon stock in Shaanxi Province decreases under all three scenarios, with the decrease in carbon stock in the Guanzhong Plain being the main reason for the decrease in carbon stock in Shaanxi Province. The area of ecological land occupied by the expansion of construction land is the smallest under the SSP126 scenario, which takes into account both socio-economic development and the need for ecological protection, and can provide a reference model for the future protection of land resources and high-quality development in Shaanxi Province.
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Response of vegetation NPP to multiscale meteorological drought in southwest China

jingjuanli

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[Objective] Since the beginning of the 21st century, the frequent occurrence of extreme drought events in southwest China has had a serious negative impact on vegetation growth. It is of great significance to study the response mechanism of vegetation to drought at different time scales.[Methods] Based on vegetation net primary productivity (NPP) data with a spatial resolution of 500m from 2001 to 2019 and standardized precipitation Evapotranspiration index (SPEI) data on a continuous scale from 1–24 months in Southwest China, Correlation analysis, maximum synthesis method and significance test were used to analyze the responses of NPP of different geomorphic types and vegetation types to multi-scale SPEI in Southwest China.[Results] (1) In the annual scale, seasonal scale and growing season, the responses of vegetation NPP and SPEI at 1-24 months are dominated by the January-March scale, and vegetation NPP has a good response to short-term drought changes, but a relatively poor response to medium and long-term drought changes. (2) The response of NPP to SPEI at 1-24 month scale showed significant spatial heterogeneity and seasonal differences. The correlation between NPP and SPEI at 1-24 month scale in summer was significantly negative in the five major geomorphic regions. The response area of NPP in spring to SPEI at July-September scale was larger than that in other seasons. The area of vegetation NPP positively correlated with SPEI from 1 to 24 months in autumn and winter was larger, reaching 72% and 79.4%, respectively. In the correlation analysis between vegetation NPP and SPEI from 1 to 24 months in growing season, the area with the largest positive correlation was Guangxi Hills, while the area with the largest negative correlation was Hengduan Mountain. (3) The responses of NPP to SPEI from 1–24 months were different among different vegetation types. Although the response characteristics of grassland, scrub and forest land to SPEI were basically similar, the trend of negative correlation between NPP and SPEI became stronger with the scales of SPEI decreased in summer for all types of vegetation. This suggests that all types of vegetation are more susceptible to drought under high temperature and drought conditions in summer.[Conclusion] The research results provide effective scientific support for the protection and restoration of the ecosystem in Southwest China, and provide important theoretical basis for disaster prevention and reduction and coping with climate change, and help formulate more targeted policies and measures to promote the sustainable development of Southwest China.
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Temporal and Spatial Changes of Soil Erosion and Its Response to Landscape Pattern in Dabie Mountains of Western Anhui in Recent 30 Years

TIAN Changyuan, ZHA Tonggang

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[Objective]The Dabie Mountain area in western Anhui Province is an important ecological transition area between the Yangtze River Basin and the Huaihe River Basin in Anhui Province. The study on the landscape pattern and soil erosion and their relationship in this area is helpful to provide reference for the regulation of landscape pattern and soil erosion control in this area.[Methods]The RULSE model was used to calculate the soil erosion modulus in the Dabie Mountains of western Anhui in the past 30 years. The changes of landscape pattern were described by landscape index, and the influence of landscape index on soil erosion was explored by partial least squares regression (PLSR).[Result]In recent 30 years, the soil erosion modulus showed the trend of decreasing first and increasing later. The areas with serious soil erosion are mainly concentrated in the central and western regions and the southern mountainous areas. In most areas, the soil erosion intensity is mainly slight and mild, and the erosion intensity of different land use types has obvious difference, which is grassland > cultivated land > forest land.The land use type and landscape pattern are generally stable. The change of landscape pattern is mainly manifested in the reduction of landscape fragmentation and the improvement of landscape heterogeneity and connectivity. Shannon’s Diversity Index (SHDI), boundary Edge Density Index (ED), Proportion of Like Adjacencies (PLADJ) and Landscape Shape Index (LSI) have significant explanatory significance for Dabie Mountain area in west Anhui Province. Shannon’s Diversity Index (SHDI), Edge Density Index (ED) and Landscape Shape Index (LSI) had significant positive effects on soil erosion, while Proportion of Like Adjacencies (PLADJ) had significant negative effects on soil erosion.[Conclusion]In the Dabie Mountains of western Anhui, the increase of landscape fragmentation and the decrease of landscape connectivity will significantly promote soil erosion.
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Spatio-Temporal Response of Supply-Demand Balance of EcosystemServices based on Land Use Change in the Middle Reaches of the Yangtze River

Zhang Chaozheng

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[Objective] Taking the middle reaches of the Yangtze River as the research area and the period from 2000 to 2018 as the research period, this study aims to reveal the spatio-temporal characteristics of supply-demand balance of ecosystem service, and further to explore the dual effects of land use change on the supply-demand balance of ecosystem service and its influencing mechanism. [Methods] The methods of quantitative matrix of supply-demand of ecosystem service, and contribution rate of land use change were employed. [Results] (1) During the research period, the supply-demand balance of ecosystem services in the middle reaches of the Yangtze River is deteriorating, which is mainly caused by the large-scale expansion of construction land and the large-scale reduction of cultivated land and forest land, resulting in the decrease of ecosystem service supply capacity and the increase of consumption demand. (2) The relationship between ecosystem service supply has changed from trade-off to synergy in time scale, and the synergy between demand and supply-demand balance has been further enhanced in time scale, but the trade-off or synergy between supply, demand, and supply-demand balance is highly heterogeneous in spatial scale. (3) Land use change in the MRYR has dual effects on the supply-demand balance of ecosystem services, and the deterioration effect is significantly greater than the improvement effect, but the types of land use change that cause the improvement and deterioration of supply- demand of ecosystem services and their sub-services have temporal heterogeneity. [Conclusion] Clarifying the qualitative and quantitative relationship among supply and demand of ecosystem services, and land use change, which helps to achieve the improvement of ecological environment by by rationally regulating the transformation of land use types.
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Volume 39, 2025 Issue 3

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