Abstract:[Objective] To systematically summarize the research progress on gravitational erosion on the Loess Plateau and propose key scientific issues and research directions that need to be addressed in the future, with the aim of providing references for the construction of watershed gravitational erosion process models and precise management of the Loess Plateau. [Methods] Based on previous research, this paper reviewed the observation and identification methods of gravitational erosion, dynamics and stochastic processes, simulation of sediment production and transport processes, and construction of watershed gravitational erosion models, with a particular emphasis on the application of airborne LiDAR technology, slope instability models based on soil mechanics, and simplified models of gravitational erosion. It also highlighted existing issues in current research, such as the limited functionality of observation methods, the lack of consideration for the stochastic nature of gravitational erosion, and the absence of simulation methods for gravitational erosion-sediment yield and transport processes. [Results] At present, progress has been made both domestically and internationally in the observation and identification of single processes of gravitational erosion, as well as in the assessment of its causes and empirical evaluation. However, high-precision observation and identification of the entire processes of gravitational erosion, along with the dynamic mechanisms of its occurrence and development, as well as process simulation, remain prominent weak points. [Conclusion] The review proposes several key scientific issues that need to be addressed in the future, including research directions such as the observation and identification of the entire processes of gravitational erosion（’development-initiation-transport-accumulation’）, the dynamic-stochastic coupling mechanisms, and the simulation of gravitational erosion-sediment production and transport processes in multi-level gullies.

Abstract:[Objective] In response to the insufficient research on the coupling of soil and water processes with carbon loss processes, the lack of long-term continuous observation data, and the weak quantitative assessment of water-carbon fluxes at the watershed scale, this paper systematically reviews the research progress of watercarbon processes in alpine peat wetlands on the Zoige Plateau. The aim is to provide a scientific basis for sustainable wetland management and achieving the "dual carbon" goals. [Methods] Based on existing domestic and international research on the Zoige Plateau, a systematic literature review was conducted. From the perspective of the Earth Critical Zone, the coupled mechanisms among hydrological, carbon, and biotic processes across multiple spheres were analyzed, and the synergistic regulation of hydrological conditions, vegetation succession, and climate change on the carbon cycle was clarified. In conjunction with the practical implementation of ecological restoration projects and policy evolution, the effectiveness of wetland protection and restoration technologies（such as rewetting and vegetation restoration） and their impact on regional carbon balance were analyzed. [Results] Hydrological conditions are the key factors regulating the carbon sink function of alpine peat wetlands, with water table fluctuations directly driving carbon accumulation and emission dynamics via redox reactions. Vegetation succession significantly impact root carbon input efficiency, yet the micro-scale coupling mechanisms of key biogeochemical processes still lack systematic verification. Human activities such as ditch drainage and overgrazing accelerate peat oxidation and carbon loss by disrupting hydrological connectivity. Although restoration techniques such as rewetting and vegetation recovery can partially restore water levels and enhance carbon sequestration, their long-term ecological effects require further investigation. The existing watercarbon coupling models are insufficient in their application to alpine wetlands with complex terrain characteristics, necessitating more accurate simulations of dissolved organic carbon transport pathways. The lack of a network observation system at the watershed scale restricts the systematic understanding of the coupled mechanisms of multiple processes, such as hydrology, erosion and carbon loss. The development of field stations has achieved remarkable results, supporting the ecological protection and restoration of alpine peat wetlands. [Conclusion] Future research should focus on the following aspects: 1) Establishing long-term observation plots to systematically monitor water retention and carbon sink dynamics in alpine peat wetlands. 2) Building a multi-scale（plot-watershed-region） and multi-element（climate-vegetation-soil-hydrology） observation network, and employing integrated methods such as fixed-point monitoring and model simulation to quantitatively analyze critical zone water and soil processes and carbon transport patterns. 3) Developing controlled experiment platforms to investigate the impact of global change（e. g., climate change, overgrazing, ditch drainage and rewetting） on water-carbon processes. 4) Strengthening the research and development of key technologies for ecological restoration of alpine peat wetlands, and building a technical system for evaluating regional ecological quality. These efforts will provide critical scientific foundations for ecological protection, restoration, and sustainable management of alpine wetlands.

Abstract:[Objective] To explore the characteristics of preferential flow development in soil in desert steppe with different degradation degrees. [Methods] Through field dyeing tracer test and indoor analysis, basic physical and chemical properties of soil with different degradation degrees were determined by the ring knife method and potassium dichromate external heating method, and the relevant data of section dyeing map were obtained by image processing software to study the spatial distribution and morphological characteristics of soil preferential flow in desert steppe with different degradation degrees in Ordos, Inner Mongolia. [Results] The total staining area ratio of moderately degraded area reached the highest value, which was 35.23%, and the maximum staining depth was 27.7 cm. The total staining area ratio of the extremely severe degradation area reached the lowest value, which was 19.54%, and the maximum staining depth was 19.6 cm. Under the condition of moderate degradation, CV decreased significantly, by about 70%, Cu also decreased significantly, and the value was less than 15. Under the condition of extremely severe degradation, the CV value was the highest, being more than 100%, and the Cu value increased significantly, being greater than 25. The development degree of preferential flow was not necessarily strong when CV was large; Cu could not explain the development degree of preferential flow. Combined with multi-dimensional indicators, the preferential flow of soil in moderate degradation area was the best. [Conclusion] The moderately degraded area shows relatively balanced characteristics of preferential flow development, high water use efficiency, and maintains good ecological functions. It is beneficial to improve soil organic matter content, increase vegetation coverage, optimize grazing management, and maintain soil health and ecological function. At the same time, moderate grazing disturbance can promote rational utilization of water resources and ecological restoration of desert steppe.

Abstract:[Objective] This study aims to reveal the soil inorganic carbon sequestration effects and the environmental impact mechanisms during the vegetation restoration process in desertified lands. [Methods] Shrub and tree sand-fixing forests from semi-fixed sandy land（0 a） to vegetation restoration of 24-56 a in the Hongshixia experimental forest farm of Yulin Mu Us Sandy Land were selected. The evolution characteristics of total inorganic carbon, water-soluble inorganic carbon, and inorganic carbon components in the 0-10 and 10-20 cm soil layers, as well as sand, silt and clay-bound inorganic carbon components, were quantified. Meanwhile, the relationships between the evolution of inorganic carbon component pools and vegetation and soil physicochemical properties were analyzed.[Results] As the restoration time of sand fixation forest prolonged, the contents of total inorganic carbon and its components in the soil of both types of sand fixation forest showed an increasing trend. Moreover, in both soil layers, the accumulation rates of mineral particle-bound inorganic carbon were relatively high. In the 0-20 cm soil layer of shrub land and arbor land, the carbon fixation rate reached 0.13 and 0.17 g/（m²·a）, which were on average 5.0,1.2 and 7.0 times higher than the accumulation rates of water-soluble inorganic carbon and sand particles and clay particles, respectively. When the vegetation was restored for 56 years, total inorganic carbon contents in the 0-10 cm soil layer of the arbor land and shrub land were 12.4 and 17.9 times greater than that of semi-fixed land, with increments 1.4-1.8 times those of the 10-20 cm soil layer. Meanwhile, the proportions of inorganic carbon in different soil components were ranked as silt-bound carbon ＞sand-bound carbon＞water-soluble carbon ＞clay-bound carbon. Further RDA and correlation analyses indicated that changes in litter mass, soil bulk density, and Ca²⁺ concentration were key factors promoting the sequestration of soil inorganic carbon and its components.[Conclusion] The improvement of environmental factors during sandfixing forest restoration can significantly promote the increase of total inorganic carbon and mineral particle-bound inorganic carbon, with silt-bound carbon being the primary form of inorganic carbon fixation. This may be one of the important mechanisms for reversing accumulation of inorganic carbon in the soil during desertification.

Abstract:[Objective] To explore how biochar（ BC） addition affects the change of soil nitrogen（N） under high N deposition. [Methods] Taking the loess plateau abandoned grassland as the research object, we set up the control（N0BC0）, high N（N9BC0）, BC addition（N0BC20） and its composite treatment（N9BC20） to analyze the change rule of different treatments on the soil nitrogen component and the spatial distribution characteristics. [Result] 1) Compared with the control, N9 BC20 treatment significantly increased the contents of TN, NH₄⁺-N and DON by 1.95, 1.70 and 1.44 times, respectively. Compared with N9BC0 treatment, N9BC20 treatment significantly increased soil TN, DON, and DTN contents in the 0-40 cm soil layer by 1.39, 1.35 and 1.22 times, respectively. Soil NH₄⁺-N, NO₃^--N and MBN contents under different treatments decreased with the increase of soil depth. 2) N9BC0 treatment decreased soil DON/DTN ratio in the 0-40 cm soil layer. However, the N9BC20 treatment increased soil NO₃^--N/DTN and DON/DTN ratios in the 0-40 cm soil layer, and promoted the conversion of soil NH₄⁺-N to NO₃^--N. 3) The NPMIs of NH₄⁺-N, DTN, and DON in the 0-40 cm soil layer under the N9BC20 treatment were all the largest, being 1.08, 1.36 and 1.60 times of that of N9BC0 treatment, respectively. 4) Regression analysis showed that soil bulk density explained 22.6% of the variation in TN, and soil total phosphorus and pH together explained 53.7% of the variation in TN. [Conclusion] BC addition can regulate the dynamics of soil N pools by altering abiotic factors in soils on the Loess Plateau and can be a potential measure for N fixation and soil fertility enhancement for soils on the Loess Plateau under the background of high N deposition in the future.

Abstract:[Objective] To clarify the effects of meteorological factors on soil moisture in different hydrological years and temporal scales, in order to provide a scientific basis for integrated management of soil and water resources under the background of climate change. [Methods] The apricot plantation in the semi-arid loess hilly region of southern Ningxia was taken as the research object. In the growing season from 2018 to 2023, soil moisture characteristics of the 0-100 cm soil layer were continuously monitored by the soil moisture sensor. The response characteristics of soil moisture to meteorological factors such as precipitation, temperature, solar radiation and relative humidity were analyzed. [Results] The average precipitation in the growing season in wet years, normal years, and dry years was 597.7, 428.5 and 298.1 mm, respectively. The volumetric soil moisture of the 0-100 cm soil layer in the growing season was 19.69%, 16.67% and 11.88%, respectively. The monthly variation of soil moisture increased first and then decreased in wet years, and decreased first and then increased in normal years and dry years. The diurnal variation of soil moisture was wavy, ’u’ type and ’w’ type in wet years, normal years and dry years, respectively. The seasonal variation pattern of soil moisture in different hydrological years all showed a relatively stable period from April to May, and a frequent fluctuation period from June to October. In general, from wet years to dry years, for the vertical spatial pattern of soil moisture, the depth of the rapidly changing layer gradually increased, the active layer increased first and then decreased, the sub-active layer gradually decreased, and the relatively stable layer gradually appeared. From wet years to the dry years the correlation between soil moisture and temperature gradually increased, the correlation between soil moisture and solar radiation and potential evapotranspiration increased first and then decreased, while the correlation between soil moisture and relative humidity changed from positive to negative, and the correlation between soil moisture and saturation vapor pressure deficit gradually weakened. The interpretation rates of meteorological factors on soil moisture changes gradually increased, which were 29.2%, 44.8% and 61.5%, respectively. At the daily, monthly, and growing season scales, the effect of precipitation on soil moisture changes gradually increased, the meteorological factors entered by stepwise regression analysis gradually decreased, and the interpretation rate of soil moisture changes gradually increased. [Conclusion] Soil moisture dynamics and the influencing factors vary with different hydrological years, time scales, as well as soil layers. Soil moisture decreases significantly in dry years. For restoration and management of plantations in the future, the drought resistance characteristics and adaptability to environmental factors of tree species should be taken into account.

Abstract:[Objective] In order to understand the impact of different vegetation restoration measures on rainfall infiltration processes on loess slopes is of critical importance.[Methods] Paired watersheds in the Nanxiaohe Valley of Xifeng, Loess Plateau, were selected to represent natural vegetation restoration（grassland landscape） and artificial afforestation（forest landscape）. From 2017 to 2018, meteorological data with a 10-minute resolution and soil moisture data at different slope positions（uphill slope, downhill gully） and five depths（10, 20, 40, 60 and 100 cm） were continuously collected. The characteristics and influencing factors of soil moisture infiltration in response to rainfall events were analyzed. [Results] 1) Different rainfall attributes significantly influenced soil wetting depth and wetting velocity. Rainfall events with greater intensity, higher total rainfall, and longer duration were more likely to trigger soil moisture responses and promote deeper infiltration. 2) Forestland facilitated deeper soil moisture infiltration. Compared with grassland, forestland exhibited deeper wetting depths（60-100, 40-60 cm）, faster wetting velocities（13.6, 8.2 cm/h）, and higher preferential flow frequencies（18.3%, 14.6%）. However, excessive vegetation coverage（e.g., at the forest downhill gully） inhibited water infiltration to certain degree. 3) Topography significantly influenced soil moisture response characteristics between slope positions. Downhill gully areas exhibited deeper wetting depths（60-100, 20-40 cm）, faster wetting velocities（13.6, 8.2 cm/h）, and higher preferential flow frequencies（18.3%, 14.6%） than uphill slope areas. [Conclusion] These findings quantitatively compare the effects of different vegetation restoration measures（grassland and forestland） on rainfall infiltration on loess slopes, can provide valuable insights into the response of runoff generation capacity under varying vegetation restoration strategies. This research offers theoretical support for ecological restoration efforts on the Loess Plateau.

Abstract:[Objective] To explore the differences of roots biomechanical characteristics of different plants and the relationships between biomechanical characteristics. [Methods] Six common soil and water conservation shrub and herb plants on the Loess Plateau were selected. Their root morphology, chemical composition, and tensile properties, as well as their relationships, were systematically studied. [Results] 1) The root diameter（D） of the six plants was mainly fine roots（＜2 mm）. The root length density（RLD）, root surface area density（RSAD）, and root mass density（RMD） at different soil depths showed significant differences（p＜0.05）. The D, RLD, RSAD and RMD of Bothriochloa ischaemum were significantly different from those of the other five plants（p＜0.05）. 2) The average root tensile strength（T_r） of B. ischaemum was 6.83, 15.03, 30.15, 7.01 and 14.15 times of that of Carex tristachya, Artemisia gmelinii, Artemisia giraldii, Caragana korshinskii, and Sophora viciifolia, respectively. T_r decreased with the increase of D, following a power function or exponential function. Additionally, the contents of cellulose, lignin, hemicellulose and holocellulose were 13.43%-52.12%, 5.87%-26.31%, 1.01%-32.18% and 17.60%-51.8%, respectively. There were significant differences in the chemical compositions and diameters among the roots of different plants（p＜0.05）. 3) Plant root ultimate elongation(ε_max) and T_r were significantly positively correlated with hemicellulose content（p＜0.05）, and D was significantly negatively correlated with the chemical composition, ε_max and T_r（p＜0.05）. The total explanation of root morphology and chemical composition on root tensile resistance was 62.91%. [Conclusion] The results provide a scientific basis and theoretical guidance for the selection of native species and the internal mechanism of root-soil reinforcement for further ecological restoration on the Loess Plateau.

Abstract:[Objective] To quantify the impact of mining area development and construction on regional soil erosion, and to provide a scientific basis for future soil erosion prevention and ecological restoration in open-pit mining areas in the Shanxi-Shaanxi-Inner Mongolia region. [Methods] Heidaigou and Harwusu coal mines, the largest open-pit mines on the Ordos Plateau, were taken as the research objects. High-resolution topography and vegetation status of the study area were obtained based on remote sensing images, statistical data and field surveys. The revised wind erosion equation（RWEQ） model and the revised universal soil loss equation（RUSLE） model were used to calculate the moduli of wind and water erosion in 1990, 2000, 2010 and 2020, respectively. The proportional changes in erosion modulus levels in the mining and natural control areas from 1990-2000, 1990-2010 and 1990-2020 were calculated to analyze the impact of open-pit mining on the two soil erosion forces. [Results] The overall moduli of wind and water erosion in the study area showed a declining trend from 1990 to 2020. The proportion of areas with reduced moduli of wind and water erosion in the mining area was smaller than that in the control area, while the proportion of areas with increased or unchanged moduli was larger than that in the control area. This indicates that open-pit mining operations have accelerated the natural erosion rates of wind and water erosion to a certain extent.[Conclusion] Soil and water conservation effors in the region have achieved periodic results. Wind and water erosion may have a certain mutual inhibitory effect, and soil and water conservation in mining areas still requires further consideration for the control of soil and water loss under combined erosion.

Abstract:[Objective] This study aimed to clarify the spatiotemporal variation characteristics of vegetation water use efficiency（WUE） in Shaanxi Province and the individual impact mechanisms of the influencing factors.[Methods] Based on MODIS data products and data provided by the National Earth System Science Data Center, we analyzed the spatiotemporal variations of WUE across different vegetation types from 2001 to 2022 in Shaanxi Province. We also examined the response mechanisms of WUE to environmental and biological factors, including air temperature（T）, precipitation（P）, normalized difference vegetation index（NDVI）, potential evaporation（ET₀）, and vapor pressure deficit（VPD）. [Results] The multi-year average WUE of vegetation in Shaanxi Province was（2.1±0.4） g/（mm·m²）（calculated in C）, exhibiting a spatial pattern of higher values in the south and lower values in the north. The multiyear average WUE showed a non-significant increasing trend（p=0.46） with a single peaked pattern within the year. Significant differences in WUE were observed among different vegetation types（p＜0.05）, with the multiyear average WUE ranked as forest＞wetland＞cropland＞shrubland＞grassland. Forests showed a significant increasing trend in WUE from 2001 to 2022（p＜0.05）, while cropland and wetland demonstrated significant decreasing trends in WUE（p＜0.05）. Partial correlation analysis revealed that the relative importance of influencing factors on WUE ranked as T（33.24%）＞NDVI（30.80%）＞VPD（27.70%）＞ET₀（6.07%）＞P（2.08%）. [Conclusion] Vegetation WUE in Shaanxi Province showed a non-significant interannual increasing trend, and changes in vegetation WUE in the north-central and southern regions were mainly influenced by environmental factors and NDVI, respectively. The findings can provide references for the assessment and management of efficient water resource utilization during the ecological construction process in Shaanxi Province.

Abstract:[Objective] This study aimed to clarify the differences in water conservation function of Pinus sylvestris var. mongolica stands at different ages.[Methods] We quantified the differences in water conservation functions of P. sylvestris var. mongolica stands at different ages（10, 15 and 20 years） based on 2023—2024 field observations of throughfall, stemflow soil water content, and litter water content. [Results] As stand age increased, the development of canopy structure significantly altered the pattern of rainfall distribution. Specifically, the proportions of throughfall and stemflow decreased, while canopy interception capacity continued to increase, highlighting the crucial role of mature canopies in redistributing rainfall. For instance, canopy interception accounted for 17.7%, 29.4% and 35.4% of rainfall in 10, 15 and 20-year-old stands, respectively. The understory litter layer also exhibited a significant age effect, with water-holding capacity increasing exponentially with the accumulation of litter, forming a synergistic effect with the water-holding function of the surface soil. The dominant role of soil water storage highlighted the stability of deep water reservoir, while differences in water storage characteristics among soil layers at different stand ages revealed dynamic vegetation-soil interactions. Water conservation function of the forest ecosystem showed a unimodal trend with stand age. Compared to 10-year-old stands, there were significant increases（61.6% and 56.0%）（p＜0.05） in 15 and 20-year-old stands. [Conclusion] The age-dependent variations in water conservation function can provide crucial references for future reforestation projects and sustainable management of P. sylvestris var. mongolica plantations.

Abstract:[Objective] This study aimed to quantitatively assess the spatial distribution of geologic hazards in the Three-River-Source National Park, explore their impact on the ecological security pattern, and provide countermeasures for regional disaster mitigation and prevention and land-use planning adjustment. [Methods] Based on GIS and the information value model, 12 assessment factors were selected from the perspective of disaster preparation and induction of geological disasters to assess the geological disaster risk of the Three-River-Source National Park, and analyze it in combination with the construction of ecological corridors and optimization of ecological security pattern. [Results] 1) The area of high-risk and extremely high-risk geological hazards of the Three-River-Source National Park is 25 614.32 km², accounting for 20.81% of the total area. 2) The main controlling disaster-forming and disaster-inducing factors of geological disasters of the Three-River-Source National Park are slope（information value=6.238 52） and distance from rural residential areas（information value=13.270 66）. There is a high correlation between geological disaster sensitivity and human activities. 3) The identified area of ecological sources is 26 833 km², with 55 ecological corridors extracted（6 080.15 km²）. Functional zones include core protected areas（39 613.58 km²）, ecological conservation areas（67 261.84 km²）, recreation and display areas（10 143.44 km²）, and traditional utilization areas（6 081.34 km²）, etc. 4) The ecological security pattern of the Three-River-Source National Park is greatly affected by geological disasters. The main affected areas are the core protected areas of the Yangtze River Source Park（65.30%）, the Lancang River Source Park（77.90%）, and the traditional utilization area of the Yellow River Source Park（88.97%）. The Yellow River Source Park is the park with the highest risk in the corridor. [Conclusion] There are obvious spatial differences in the impact of geological hazards on the ecological security pattern in the Three-RiverSource National Park, and corresponding preventive and control measures should be taken in a zoned and categorized manner.

Abstract:[Objective] This study aimed to investigate the phenology of vegetation, i.e., the seasonal changes in the growth and development of vegetation in the Loess Plateau region of Gansu Province, and to gain a deeper understanding of how climate change affects the growth patterns of vegetation in this area. [Methods] Based on MODIS NDVI datasets, meteorological data, digital elevation models（DEM）, and standardized precipitation evapotranspiration index（SPEI） data from 2002 to 2021, the start of the growing season（SOS）, end of the growing season（EOS）, and length of the growing season（LOS） of vegetation in the Loess Plateau region of Gansu Province were extracted. Theil-Sen trend analysis and Mann-Kendall tests were used to explore the spatiotemporal dynamics of SOS, EOS and LOS. Partial correlation analysis was employed to investigate the relationships between vegetation phenology and temperature, precipitation, drought, and topography. The Hurst index and random forest regression model were utilized to predict future changes in vegetation phenology in the Loess Plateau region of Gansu. [Results] 1) The SOS of vegetation in the Loess Plateau region of Gansu was concentrated between day 81 to 138, with a change rate of-4.5 d/10 a; the EOS was concentrated around day 266 to 305, with a change rate of-0.4 d/10 a; and the LOS was concentrated around 131 to 218 days, with change rate of 2.6 d/10 a. 2) During the study period, temperature was positively correlated with SOS（90%） and EOS（54%）, and negatively correlated with LOS. Precipitation was positively correlated with SOS（85%）, and negatively correlated with EOS（57%） and LOS. SOS in the western part of the Longxi Loess Plateau and EOS in the southern part of Tianshui were significantly negatively correlated with drought, while LOS in some areas such as Lanzhou, Linxia and Dingxi was significantly positively correlated with drought. 3) In the future, in the southern part of the Loess Plateau region of Gansu, SOS is expected to advance, EOS is expected to delay, and LOS is expected to extend; in the northern part, SOS is expected to delay, EOS is expected to advance, and LOS is expected to shorten. [Conclusion] From 2002 to 2021, due to significant influences of meteorological factors, the growth cycle of vegetation in the Loess Plateau region of Gansu has effectively lengthened, and has improved the local ecological environment and promoted the stability and sustainable development of the ecosystem. In the future, efforts should be made to further strengthen ecological environment protection, promote in-depth ecological restoration and governance, and make greater contributions to the construction of ecological civilization in the Loess Plateau region of Gansu.

Abstract:[Objective] To gain a deeper understanding of the pattern of groundwater changes in Pinus sylvestris var. mongolica plantations in sandy areas, as well as the driving mechanisms of climate change and anthropogenic activities. [Methods] The groundwater depth of P. sylvestris plantation in the sandy land from 2018 to 2023 was studied, and the groundwater depth of sandy grassland was used as the control. The groundwater depth of P. sylvestris plantation on the southern edge of the Horqin Sandy Land and its response to climate change and anthropogenic activities were analyzed by using methods including double cumulative curve method, grey correlation method, sensitivity analysis, relative contribution rate method, and cumulative anomaly method.[Results] During the 6-year period, groundwater depth in P. sylvestris plantation on the southern edge of the sandy land showed a decreasing trend（0.385 m/a）. The influence of various meteorological factors on groundwater depth was ranked as: precipitation＜relative humidity＜evaporation＜average temperature. The sensitivity of groundwater depth to these factors was ranked as relative humidity＜evaporation＜average temperature＜precipitation. The contribution rate of various factors to groundwater depth was ranked as average temperature＜evaporation＜precipitation＜relative humidity. According to the cumulative anomaly method, 2020 was identified as a year of abrupt changes in meteorological factors. Climate change reduced groundwater depth and variability in the study area. P. sylvestris plantation increased groundwater depth during dry years and decreased it during wet years. [Conclusion] Both climatic factors and anthropogenic activities collectively influence groundwater depth in the study area. There are significant differences in the impact of different meteorological factors on groundwater depth. Abrupt climate changes and P. sylvestris plantation can alter the hydrological regime of groundwater.

Abstract:[Objective] This study aimed to reveal the material transport characteristics and spatial differentiation pattern of wind-blown sand into the Yellow River along the Ulan Buh Desert in the upper reaches of the Yellow River. [Methods] A typical transition zone where the desert directly contacts the river was selected. Based on surface humidity gradients and sediment grain size differentiation, the study area was subdivided into three subregions, i.e. the marginal zone（X1）, transition zone（X2）, and nearshore zone（X3）. The grain size composition and sediment transport characteristics of surface sediments were systematically analyzed. [Results] The marginal zone was dominated by medium-fine sand, with an average particle size of 145.03 μm and strong wind erosion. The transition zone was dominated by sand, with an average particle size of 217.13 μm. The nearshore area was dominated by silt, with an average particle size of 24.95 μm, and the hydrodynamic influence was obvious. The sorting of surface sediments in each region was poor, the skewness was extremely negative deviation-near symmetry-extremely negative deviation, and the kurtosis was narrow-medium-narrow. The proportion of saltation components in the marginal zone was more than 95%, showing a two-stage distribution indicative of long-distance aeolian sand transport. The transition zone was dominated by saltation, and the suspended component accounted for only about 3%. The suspended, saltation, and creep components in the near-shore area accounted for 26.1%, 67.2% and 6.7%, respectively. The contribution rate of 0-10 cm layer was 62%-78%, and the near surface was the core area of wind-blown sand activity. The particle size ranges of the erodible particles in the marginal zone, the transition zone, and the nearshore zone were 170.3-446.5, 137.5-401.2 and 123.6-291.0 μm, respectively. [Conclusion] The marginal zone is the key area for wind erosion control. The wind erosion effect can be weakened and the release of particles can be reduced by setting sand barriers and increasing vegetation coverage.

Abstract:[Objective] Soil hydraulic properties under long-term vegetation restoration play a critical role in the ecological service functions of vegetation construction. This study aimed to explore the mechanisms by which vegetation attributes influence soil hydraulic properties under different vegetation restoration types. [Methods] Four typical plantations and natural forests in the Loess Plateau region of western Shanxi, including Pinus tabulaeformis plantation, Platycladus orientalis plantation, Robinia pseudoacacia plantation, and one natural secondary forest, were selected as the research subjects. Understory vegetation diversity, vegetation attributes, and soil water retention properties were measured to compare and analyze the influence of vegetation restoration methods on soil hydraulic properties. [Results] 1) The natural secondary forest showed significantly higher tree height and branch height, and greater canopy width compared to the plantations. For instance, the values of tree height, branch height, and canopy width of the natural secondary forest were 58.84%, 254.4% and 32.59% higher, respectively, than those of the R. pseudoacacia plantation. Additionally, the Shannon-Wiener diversity index and Simpson’s dominance index of the natural secondary forest were significantly higher than those of the plantations. 2) Regarding soil hydraulic properties, the natural secondary forest exhibited higher peak volumetric water content, saturated water content, and field capacity during the growing season. The soil volumetric water content in the plantations, especially in the R. pseudoacacia plantation, was consistently lower than that in the natural secondary forest. 3) Both soil properties and vegetation attributes had significant relationships with soil hydraulic properties. For instance, the total nitrogen content and tree height of the natural secondary forest were 52.67% and 37.04% higher, respectively, than those of the R. pseudoacacia plantation. The saturated water content of the natural secondary forest was 6.09% higher than that of the R. pseudoacacia plantation. [Conclusion] The natural secondary forest demonstrates clear advantages in regulating soil water balance and improving soil hydraulic properties. In contrast, the plantations, due to their simpler vegetation structure, shows deficiencies in improving soil hydraulic properties. Therefore, vegetation restoration on the Loess Plateau should emphasize biodiversity enhancement, fully utilize the advantages of natural secondary forests while integrating plantations to achieve sustainable development.

Abstract:[Objective] To explore the differences in the relationship between herbaceous diversity and soil physicochemical properties of different stand types, [Methods] Four typical plantations in the loess region of northwestern Shanxi Province, including Pinus tabuliformis pure plantation, Populus microphylla pure plantation, P. tabuliformis and P. microphylla mixed plantation, and P. microphylla and Caragana korshinskii mixed plantation, were studied to analyze the differences in herbaceous diversity and soil physicochemical properties among different stand types, and to study their correlations. [Results] 1) There were 35 species of understory herbs in 12 families and 30 genera in the study area, and the dominant species were Poaceae. There were significant differences in the Simpson diversity index, Pielou evenness index, and Margalef richness index among the four typical plantations（p＜0.05）, with the P. microphylla and C. korshinskii mixed plantation showing the highest values. 2) There were also significant differences in soil physicochemical properties among the four typical plantations（p＜0.05）, with the P. microphylla pure plantation and the P. microphylla and C. korshinskii mixed plantation exhibiting the best soil properties. 3) Correlation analysis and redundancy analysis showed that there were differences in the effects of soil total phosphorus and soil water content on herbaceous diversity among different stand types. Soil water content was negatively correlated with herbaceous diversity in P. tabuliformis pure plantation（p＜0.05）, but positively correlated with herbaceous diversity in mixed forest（p＜0.05）. Soil total phosphorus was significantly positively correlated with herbaceous diversity in P. tabuliformis pure plantation, and in P. microphylla and C. korshinskii mixed plantation（p＜0.05）, and negatively correlated with herbaceous diversity in P. microphylla pure plantation, and in P. tabuliformis and P. microphylla mixed plantation. [Conclusion] Soil total phosphorus and soil water content are the main factors affecting herbaceous diversity. The results of this study are of great significance for understanding the ecological functions of understory herbaceous plants and soil properties in the loess region of northwestern Shanxi Province.

Abstract:[Objective] The objective of this study was to reveal the variation patterns of rill sediment transport capacity with slope gradient and flow rate, improve the sediment transport theory, and construct soil erosion prediction models. [Methods] Through indoor flume tests with added soil, the rill sediment transport capacity of four typical soils on the Loess Plateau（silty clay, sandy loam, silty loam and silt） was measured under combinations of five slope gradients（9°, 12°, 15°, 18° and 21°） and four flow rates（5, 7, 9 and 11 L/min）. The trends in rill sediment transport capacity with slope gradient and flow rate for four soils were analyzed, and prediction models for rill sediment transport capacity were developed.[Results] 1) The rill sediment transport capacity of the four soils increased with increasing slope gradient or flow rate. At a slope of 15° or under flow rates of 7, 9 and 11 L/min, significant differences were observed in the rill sediment transport capacity among the four soil types（p＜0.05）. 2) The rate of increase in rill sediment transport capacity among the four soil types exhibited a nonlinear trend between adjacent slope gradients（or flow rates）. 3) The response of rill sediment transport capacity to slope gradient（or flow rate） for different soils under varying slope gradients（or flow rates） could be well described by power functions（R²: 0.713-1.000）. Given that rill sediment transport capacity was influenced by the coupling effect between slope gradient and flow rate, binary exponential function-based prediction models for rill sediment transport capacity were developed for the four soils, with both slope gradient and flow rate being incorporated as variables. The constructed models all exhibited high predictive accuracy（R²: 0.839-0.945）. [Conclusion] The rill sediment transport capacity exhibits complex response to slope gradient and flow rate for four soils on the Loess Plateau. The power function model demonstrates superiority in characterizing the response of rill sediment transport capacity to slope gradient or flow rate.

Abstract:[Objective] This study aimed to clarify the mechanisms by which biological soil crust（BSCs） influence overland flow resistance, focusing on the effects of mixed biocrust communities on grain resistance（f_g） and form resistance（f_f）. [Methods] A total of 84 undisturbed soil samples with three different mixed BSCs compositions（algae-dominated, equal algae-moss ratio, and moss-dominated） were collected, flume scouring experiments under seven combinations of slope gradient and flow discharge were set up, and the response of overland flow resistance characteristics to BSCs was systematically investigate under different hydrodynamic conditions.[Results] 1) Biocrust coverage reduced the velocity of overland flow by 8.5%-57.3% and increased water depth by 5.4%-70.6%. The flow slowing effect of mixed BSCs was enhanced significantly with the increasing proportion of moss crust, with the flow slowing effect of moss-dominated community（T3） being 1.1 to 2.5 times greater than that of other mixed BSCs. Increased moss proportion reduced Froude number（Fr） and increased Reynolds number（Re） without altering the flow pattern or flow regime. 2) Coverage of mixed communities of biological crust significantly increased the total resistance（Darcy-Weisbach resistance coefficient） f, which decreased as a power function with the increase of Re and Fr（R²≥0.46, p＜0.01）,and showed a significant positive correlation with the biomass of moss crust(M_moss)（ p＜0.05）. 3) BSCs coverage significantly increased the f_f of overland flow, which was the dominant part of the f of overland flow under different slope gradients, flow discharges, and BSCs coverage conditions. The f_g was significantly correlated with sediment load（q_s）（p＜0.05）, and f_f was positively correlated with M_moss（p＜0.05）. 4) The f_g calculated by Savat model was not applicable to overland flow with low q_s under BSCs coverage. Based on the influencing factors of f_g and f_f, a new equation for the f of overland flow under BSCs coverage was established: f=Re^{-1.021 4}×M_moss^0.311×10^3.793. [Conclusion] Under BSCs coverage, the main reason for the increase of the f of overland flow is the increase of the f_f, which is mainly affected by the proportion of moss crust. The study is of great significance for clarifying the mechanism of BSCs affecting overland flow resistance, and provides a theoretical basis for using BSCs to prevent and control soil erosion on the Loess Plateau.

Abstract:[Objective] To investigate the effects of magnetic field intensity on the movement patterns of soil water and salt under drip irrigation with different water sources, and to determine the optimal magnetic field strength. [Methods] A field experiment was conducted from May 2023 to October 2024 in Dalate Banner. The experiment included two types of irrigation water sources（Yellow River water [F] and slightly saline water [B]） and four levels of magnetic field intensity（M）（0.5 T, 0.3 T, 0.1 T and 0 T）. The study examined the mechanisms by which different treatments affect soil water and salt dynamics, salt leaching and ion migration. [Results] Magnetized water drip irrigation significantly increased the soil volumetric water content in the crop root zone, promoted salt leaching, alleviated water-salt stress in the root zone, and effectively reduced the mass fractions of Cl^-, SO₄^2-and Na+ in the soil. Under different magnetic intensities, FM and BM treatments showed significant differences. When the magnetic field intensity was 0.3 T, the root-zone soil volumetric water content of FM3 and BM3 treatments increased by 3.03%-3.35% and 1.58%-3.16%, respectively, and the desalination rates increased by 8.83%-14.56% and 7.07%-13.62%, respectively, compared with FM0 and BM0. These treatments also achieved better Cl^-and Na⁺ removal, with FM3 showing removal rates of 19.17%-31.67% and 33.95%-42.91%, and BM3 achieving 5.20%-21.03% and 20.41%-26.02%, respectively. When the magnetic field intensity was 0.5 T, SO₄^2-removal was most effective, with FM5 and BM5 reaching 30.97%-35.22% and 25.81%-26.02%, respectively. In addition, magnetized water drip irrigation effectively reduced areas affected by soil water-salt stress and showed potential in improving the soil water-salt environment. Fitting analysis indicated that a magnetic field range of 0.29-0.38 T was optimal for improving the root-zone water-salt environment. Drip irrigation with magnetized water using both irrigation sources can enhance root-zone soil moisture and promote salt leaching. [Conclusion] Magnetized water drip irrigation significantly improves the root-zone soil water-salt environment. A magnetic field strength of 0.3-0.4 T is optimal for highly saline-alkali farmland in the Yellow River irrigation area. These findings provide theoretical support for improving saline-alkali land and the efficient utilization of water resources in the Yellow River irrigation area.

Abstract:[Objective] This study aimed to clarify the spatial distribution patterns of soil erosion, soil aggregates, and aggregate-associated organic carbon in the grassland and terraced fields in the agro-pastoral ecotone of Qilian Mountains, and to elucidate how soil erosion drives the redistribution of aggregate-associated organic carbon along slopes. The findings will provide a theoretical basis for soil conservation and carbon sequestration in this region. [Methods] Typical grassland and terraced fields were selected as the study objects. The ¹³⁷Cs tracer method was used to estimate the rates of water erosion and tillage erosion. The wet sieving method was used to separate aggregates into four particle sizes fractions. The mean weight diameter（MWD）, geometric mean diameter（GMD）, organic carbon content in each aggregate size fraction, and organic carbon content were calculated.[Results] 1) The soil ¹³⁷Cs inventory exhibited a "decrease-increase-decrease-increase" trend along the slope direction of the grassland. However, the soil ¹³⁷Cs inventory exhibited a fluctuating increase, with a sharp mutation at the junction of Terrace 1（T1） and Terrace 2（T2）. 2) The total erosion rates ranged from-17.55 to 4 579.69 t/（km²·a） in grassland and-1 358.10 to 11 226.20 t/（km²·a） in terraces. Higher soil erosion rates were found at the top of each terrace than that in the grassland. 3) The aggregate composition varied among different slope positions. In the grassland, large macroaggregates（ ＞2 mm） dominated at all landscape positions, whereas in terraced fields, small macroaggregates（0.25-2 mm） were dominant. The MWD and GMD of grassland aggregates were higher than those of terraces. Along the downslope direction of terraced fields, the mass fraction of ＞2 mm aggregates and aggregate stability showed a fluctuating increase, while the fraction of ＜0.25 mm aggregates exhibited the opposite trend. For both grassland and terraced fields, the aggregate-associated organic carbon showed a fluctuating trend of increase in the downslope direction, but the increase in organic carbon content at the foot position of the terraced fields（191.15% higher than that at the summit） was significantly greater than that in the grassland（25.70% higher than that at the summit）. [Conclusions] In the agro-pastoral ecotone of the Qilian Mountains, the combined effects of tillage erosion and water erosion in sloping croplands exacerbates the fragmentation and migration of ＞2 mm aggregates, reducing aggregate stability at the slope summit, and consequently leading to organic carbon depletion at the summit and accumulation at the foot position of the slope.

Abstract:[Objective] To clarify the relationship between stumping and soil moisture in degraded seabuckthorn forests, a systematic study is conducted to evaluate the effects of stumping on soil moisture dynamics, aiming to provide theoretical and technical support for the restoration of seabuckthorn forests through stumping in the Ningxia Loess area. [Methods] Two treatments were established: stumping（height≤30 cm） and no stumping, each with four replicates, arranged in a randomized block design. [Results] 1) The volumetric soil moisture content in the surface layer（0-20 cm） under the stumping treatment increased significantly by 4.10%-70.01%, compared to the no stumping treatment. In the shallow layer（20-80 cm）, it increased significantly by 8.99%-11.12%. In the middle layer（80-180 cm）, it increased significantly by 14.36%-28.97%. In the deep layer（180-280 cm）, it increased significantly by 5.48%-29.21%. 2) The soil water storage in the 0-280 cm profile under stumping significantly increased by 7.11%-22.90%, and the soil moisture deficit index significantly increased by 98.16%-300.00% compared to the no stumping treatment. 3) In the surface layer（0-20 cm）, total soil porosity under stumping significantly decreased by 1.90%, non-capillary porosity decreased by 44.84%, while capillary porosity increased by 1.18%. [Conclusion] Stumping of degraded seabuckthorn forests significantly enhances soil moisture content, water storage capacity, and capillary porosity, while reducing the soil moisture deficit.

Abstract:[Objective] Freeze-thaw cycle is an important physical process in alpine regions, the objective of this study was to elucidate the impact of freezing and thawing on the microstructure of alpine meadow soils with varying degrees of degradation. [Methods] Alpine meadow soils with different degradation degrees in Menyuan, Qinghai Province, were used as the research objects, and different root contents were used to characterize different degradation degrees. Freeze-thaw cycle test and scanning electron microscopy were carried out on remolded specimens to analyze the effects of different numbers of freeze-thaw cycles, water contents, and root contents on the microstructure of meadow soils under freeze-thaw conditions. [Results] The pore fractal dimension of alpine meadow soils continued to increase with the increase in the number of freeze-thaw cycles, the average diameter of the pores showed a decreasing trend and stabilized after seven freeze-thaw cycles, the increase in porosity was concentrated in the first four freeze-thaw cycles. The higher the mass water content of the meadow soil, the greater the increase in porosity after freezing and thawing. When the mass water content was＞40%, the fractal dimension of the pores of the specimens increased dramatically after freezing and thawing, while the average diameter of the pores decreased significantly. Plant roots significantly inhibited the effect of freezing and thawing on the pore space of alpine meadow soil, and the decrease of the average diameter of the pore space after freezing and thawing decreased from 16.19% to 0.16%, and the increase of the porosity decreased from 33.22% to 18.17% with the increase of root content of the specimen.[Conclusion] The higher the degradation degree of alpine meadows, the greater the impact of freezing and thawing on the microstructure of the soil. The plant root system can significantly affect the stability of the soil structure. The findings of the study offer a foundation for further theoretical inquiries into the dynamics of degradation control and its influencing factors within alpine meadows.

Abstract:[Objective] This study aimed to reveal the soil texture difference and water-holding capacity change characteristics of four typical parts of blowout pits in the Hulunbuir grassland.[Methods] The blowout pits were divided into four parts: the edge area（A area）, the sand pit area（B area）, the severe sand accumulation area（C area）, and the mild sand coverage area（D area）. The natural grassland was used as the control（CK area）. Correlation analysis and PCA analysis of soil properties including soil particle size, bulk density, water-holding capacity, etc. in the 0-200 cm soil layer of each pit were carried out.[Results] 1) The soil in the 0-200 cm soil layer of blowout pits in the Hulunbuir grassland was mainly medium sand, there was no gravel, and the average particle size was B area（1.41Φ）＞A area（1.48Φ）＞C area（1.52Φ）＞D area（1.98Φ）＞CK area（2.45Φ）. 2) There were significant differences in soil particle size parameters of the four parts of the blowout pits. The sorting coefficient was generally poor, the peak value was sharp and narrow, the skewness was extremely positive, and the fractal dimension was generally distributed around 2.1-2.2. 3) The average particle size gradually decreased along the main wind（northwest wind）. The sorting effects of C and D were stronger, while the sorting effects of A and B were weaker. 4) Soil bulk density of wind erosion pits was between 1.55-1.70 g/cm³, soil water content was CK area（4.51%）＞A area（4.4%）＞D area（4.35%）＞B area＞（4.23%）＞C area（4.2%）, and field water-holding capacity was CK area（17.97%）＞D area（16.95%）＞A area（15.53%）＞B area（15.26%）＞C area（14.51%）. 5) Soil water content in different parts of blowout pits was positively correlated with clay, silt, fine sand, and very fine sand fractions, and negatively correlated with medium sand, coarse sand, and very coarse sand fractions.[Conclusion] The overall average particle size of blowout pits becomes finer along the main wind direction. Water-holding capacity is the weakest in the C area, and strongest in the D area. The findings provide a theoretical basis for the management of blowout pits.

Abstract:[Objective] This study aims to decompose and spatially map the uncertainties in projected biodiversity changes contributed by three key factors Species Distribution Models（SDMs）, General Circulation Models（GCMs）, and Shared Socioeconomic Pathways（SSPs） to better understand the sources of uncertainty in biodiversity change and make conservation and management decisions. [Methods] Using three well-established SDMs and eight critical climate variables, the study developed ecological niche models for ten plant species. Model performance was assessed via the area under the receiver operating characteristic curve（AUC）. The rigorously validated niche models were projected onto future climate scenarios combining five GCMs and four SSPs, generating 60 distinct biodiversity distribution maps for the Loess Plateau（3SDMs×5 GCMs×4 SSPs,2060-2080）. Uncertainty associated with different components was precisely quantified through three-way analysis of variance and spatially mapped using ArcGIS. [Results] All three SDMs demonstrated strong predictive performance, with mean AUC values exceeding 0.8 across all ten species, indicating a high level of accuracy. However, significant differences were observed among projection results from different SDMs, GCMs and SSPs combinations, with an average variation of 34%. Uncertainty decomposition revealed that SDMs and GCMs together contributed approximately 60% of the total uncertainty, far outweighing the uncertainty associated with SSPs in biodiversity simulation. [Conclusion] Comprehensive consideration of uncertainty differences among SDMs, GCMs and SSPs is crucial for climate change adaptation and biodiversity conservation. The quantitative uncertainty mapping methodology introduced in this study can effectively address the limitations of existing research and substantially enhance the scientific rigor and effectiveness of policy formulation.

Abstract:[Objective] This study aimed to investigate the effects of meteorological factors and crop planting area changes on maize water requirements in the Ningxia Yellow River irrigation area. [Methods] The PenmanMonteith equation and single crop coefficient method were employed to calculate maize water requirements and analyze their spatiotemporal variations in the Ningxia Yellow River irrigation area. The rescaled range analysis（R/S） method was used to predict future trends in maize water requirements. Partial derivative-based sensitivity analysis and logarithmic mean divisia index（LMDI） decomposition were utilized to examine the impacts of meteorological factors and planting area changes on maize water requirements and to identify the primary influencing factors. [Results] Maize water requirements exhibited distinct spatial heterogeneity, increasing from the central to the northern and southern ends of the irrigation area, with overall lower values in southwest than in northeast. Future water demand predictions indicated an increasing trend for maize water requirements at the Huinong and Yinchuan stations. Among meteorological factors, relative humidity showed the highest sensitivity coefficient. Unit-area maize water requirements increased with rising maximum temperature, minimum temperature, wind speed, and sunshine hours, but decreased with increasing relative humidity. Throughout the study period, changes in crop planting area were the primary factor driving variations in total maize water requirements. [Conclusion] The expansion of maize planting scale has a significant impact on the increase of total water requirements, while meteorological factors play a relatively minor role in the variation of total water demand during this period. The research findings can provide decision-making support for determining rational crop planting structures and scales, as well as adaptive water resource management in irrigation areas under climate change scenarios.

Abstract:[Objective] This study aims to quantify the effects of climate change and human activities on carbon sequestration in the terrestrial ecosystems of the Qinghai Lake basin, providing a scientific basis for assessing carbon sequestration capacity of regional vegetation, formulating climate change response measures, and implementing ecological restoration.[Methods] Based on MODIS remote sensing data, net ecosystem productivity（NEP） was estimated. Trend analysis, stability analysis, Hurst index, and center migration methods were employed to investigate the spatiotemporal patterns and evolution trends of NEP in the Qinghai Lake basin from 2000 to 2021. Partial correlation, multiple correlation, and residual analysis were used to quantitatively separate the effects of human activities and climate change on spatiotemporal differentiation of NEP. [Results] 1) Over the 22-year period, NEP in the Qinghai Lake Basin showed an increasing trend at a rate of 2.16 g/（m²·a）, with a spatial distribution pattern of higher values in the southeast and lower in the northwest, radiating outward from Qinghai Lake with diminishing intensity. Nearly 80% of the area exhibited an upward NEP trend, with extremely significant and significant increases accounting for 61.50% and 17.61%, respectively. Areas with declining NEP trends were distributed along the western, northern, and northeastern shores of Qinghai Lake, with sporadic occurrences in the northern part of the basin. Approximately 77.32% of the basin exhibited low and extremely low volatility in NEP changes, while 89.19% of the areas with increasing NEP were projected to shift to a decreasing trend in the future. The center of carbon sources generally migrated from the northwest to the southeastern shore of Qinghai Lake, covering a straight-line distance of about 171.72 km, whereas the center of carbon sinks shifted westward by approximately 2.68 km. 2) The average partial correlation coefficients between interannual NEP changes and temperature, precipitation, solar radiation, and land surface temperature were 0.141 3, 0.124 7,-0.182 9 and-0.002 2, respectively. Temperature and precipitation showed positive correlations with NEP, while solar radiation and land surface temperature exhibited negative correlations. All correlations were statistically insignificant. 3) Residual analysis indicated that regions where both climate change and human activities jointly promoted NEP increases accounted for 95.10% of the study area. [Conclusion] Climate and human activities jointly affect NEP changes. Over the past two decades, most areas of the Qinghai Lake Basin’s terrestrial ecosystem have seen a notable increase in carbon sink capacity. Under a warmer and wetter climate background, ecological measures in Qinghai Province-such as grazing prohibition, desertification control, and afforestation-have collectively boosted NEP growth. However, increasing human activities, frequent construction projects, and the rising water level and expanding area of Qinghai Lake may hinder further NEP improvement.

Abstract:[Objective] This study aims to investigate the effects of wind-rain complex erosion on soil aggregate organic carbon in the Loess Plateau. [Methods] Laboratory-based rainfall simulation and wind tunnel experiments were conducted to study the loss mechanisms of organic carbon and its labile fractions in 5-2 mm soil aggregates under different erosion forces and erosion sequences. [Results] 1) Under wind-rain complex erosion, the mass fractions of soil aggregate organic carbon（SOC）, easily oxidizable organic carbon（EOC）, particulate organic carbon（POC）, and dissolved organic carbon（DOC） decreased by 7%-25%, 8%-29%, 52%-71% and 16%-32%, respectively, compared with single-force erosion. 2) Under wind-rain complex erosion, the mass fractions of SOC, EOC, POC, DOC, and microbial biomass carbon（MBC） under wind-then-rain erosion（WR） decreased by 19%, 20%, 4%, 13% and 9%, respectively, compared with rain-then-wind erosion（RW）. 3) Aggregate organic carbon and its labile components exhibited different sensitivity response to different erosion forces: EOC showed higher sensitivity to rain erosion, while POC was more sensitive to wind erosion and wind-rain complex erosion. [Conclusion] Wind-rain complex erosion more significantly exacerbates the losses of aggregate organic carbon and labile organic carbon fractions compared to single-force erosion, and the degree of SOC loss shows dependence on erosion sequence. These findings provide theoretical support for developing soil erosion prevention and organic carbon sequestration strategies in regions affected by wind-rain complex erosion.

Abstract:[Objective] "Mechanical sand barrier+Haloxylon ammodendron" is a widely used composite sandfixing measure in desert regions. This study aims to investigate the variation characteristics of soil carbon and nitrogen stocks in areas under five different measures: ecological barriers+Haloxylon ammodendron（El+H）, plastic net barriers+Haloxylon ammodendron（Pc+H）, woven bag barriers+Haloxylon ammodendron（Wn+H）, straw checkerboard barriers+Haloxylon ammodendron（Gs+H）, and clay barriers+Haloxylon ammodendron（Cy+H）. [Methods] Soil samples collected from areas under five different measures in Minqin Shazuidun precision sand-fixing afforestation demonstration area were selected as the research objects. The soil in mobile sand dune+Haloxylon ammodendron plantation was used as the control（CK）. Soil carbon and nitrogen stocks and their correlation with physicochemical properties such as electrical conductivity, pH, bulk density, and soil moisture content were measured and analyzed. [Results] 1) The five sand-fixing measures significantly affected soil electrical conductivity, soil moisture content, and bulk density（p＜0.05）, but showed no significant effect on soil pH（p＞0.05）. Significant differences existed in soil physicochemical properties among different soil layers（p＜0.05）. 2) The mass fraction of soil organic carbon（SOC） gradually decreased with increasing soil depth, reaching its maximum in the 0-10 cm layer. The mass fraction of total nitrogen showed an initial increase followed by decrease, peaking in the 40-60 cm soil layer. 3) All five sand-fixing measures significantly affected SOC and total nitrogen storage（p＜0.05）. The carbon sequestration rate showed an increasing trend, with the Gs+H measure achieving the highest rate. The nitrogen sequestration rate initially increased then decreased. 4) The effects of sand-fixing measures on SOC storage, total nitrogen storage, and carbon and nitrogen sequestration rates were extremely significant（p＜0.01）. Additionally, soil depth significantly affected these parameters（p＜0.05）. The interaction between sand-fixing measures and soil depth had a significant effect on SOC storage, total nitrogen storage, and carbon and nitrogen sequestration rate. Significant correlations existed among all measured indicators. [Conclusion] The sand-fixing measure of Gs+H demonstrates optimal performance in improving soil properties and carbon-related indicators, which provides crucial scientific evidence and practical guidance for ecological restoration and management of desertified lands in arid and semi-arid regions.

Abstract:[Objective] To investigate the effects of nitrogen fertilizer synergists on wheat growth, yield, and nitrogen use efficiency.[Methods] Five treatments were set up: control（ CK）, U（T1）, U+NBPT（T2）, U+DMPP（T3） and U+NBPT+DMPP（T4）. The fertilizer was applied at the jointing stage through integrated water and fertilizer management. The effects of each treatment on the growth, yield, nitrogen use efficiency, and physiological characteristics of winter wheat were compared. [Results] Compared with T1, treatments T2 to T4 all improved the plant height, dry matter accumulation, and yield. In particular, T4 significantly increased dry matter and yield by 32.35% and 17.19%, respectively. Treatments T2 to T4 significantly improved wheat water and nitrogen use efficiency, as well as the soil nitrogen supply capacity. Under T4, nitrogen uptake efficiency, partial factor productivity, agronomic efficiency, nitrogen contribution rate, and water use efficiency increased by 18.96%, 17.19%, 89.36%, 61.57% and 17.59%, respectively. At the booting stage, the contents of soil NH₄⁺-N, NO₃^--N, and the apparent nitrification rate of NH₄⁺-N were significantly reduced by 6.04%, 18.74% and 5.03%, respectively, compared with T1. Additionally, the activities of soil urease, nitrate reductase, nitrite reductase, and hydroxylamine reductase were significantly reduced by 30.37%, 20.04%, 14.54% and 7.04%, respectively, compared with T1. The application of inhibitors with urea increased the chlorophyll content and antioxidant enzyme activity, reduced malondialdehyde content and superoxide radical production rate, delayed leaf senescence, enhanced nitrogen uptake in the later growth stage, and improved nitrogen use efficiency. [Conclusion] The combined application of NBPT and DMPP with urea promotes wheat growth, optimizes soil nitrogen-metabolizing enzyme activities and leaf physiological characteristics, enhances photosynthetic capacity, delays leaf senescence, and ultimately improves wheat yield and both water and nitrogen use efficiency. It is the optimal strategy for applying inhibitors in integrated water and fertilizer management. The results of this study can provide a basis for the efficient application of nitrogen fertilizer in wheat.

Abstract:[Objective] To clarify the effects of biochar application rate and irrigation volume on the salt reduction in sodic saline soil of the Yellow River Delta and to identify the optimal ratio between the two. [Methods] A twofactor five-level orthogonal rotation combination design was employed in soil column experiments to simulate the effects of irrigation volume（1.00, 1.07, 1.25, 1.43 and 1.50 times the saturated soil moisture content, θ_s） and biochar application rates（1.00%, 1.59%, 3.00%, 4.41% and 5.00% of soil mass in the 0～20 cm layer, S_w） on soil volumetric moisture content, electrical conductivity, pH, and ion mass fraction in sodic saline soil. The optimal water-biochar combination ratio was determined using the analytic hierarchy process and multiple regression equations. [Results] 1) The treatment with 4.41% S_w and 1.43 θ_s achieved the highest soil volumetric moisture content（31.71%） and pH（8.50）. In contrast, the treatment with 3.00% S_w and 1.25 θ_s showed the most significant reductions（p＜0.05） in electrical conductivity, Na+ mass fraction, and sodium adsorption ratio（SAR） compared to the untreated soil, with decreases of 82.05%, 89.71% and 86.43%, respectively. 2) Both water and biochar synergistically affected the comprehensive evaluation index of salt reduction effect in sodic saline soil, with irrigation having greater influence than biochar application. The comprehensive evaluation index initially increased but subsequently decreased with the increasing application rates of both factors. The maximum evaluation index（0.72） for salt reduction in sodic saline soil was obtained at an irrigation level of 1.37 θ_s combined with a biochar application rate of 3.45% S_w. [Conclusion] To enhance sodic saline soil quality in the Yellow River Delta, the synergistic combination of 3.45% S_w biochar application and 1.37 θ_s irrigation is the most effective strategy for salt reduction in saline-alkali soil. The research results provide a theoretical basis for saline-alkali soil remediation.

Abstract:[Objective] The Weibei dryland is a typical rain-fed agricultural area characterized by uneven temporal and spatial rainfall distribution, leading to insufficient water supply during key growth stages of fruit trees. This study aims to evaluate the effectiveness of a rain collection and infiltration carburizing technology（RCIC） in improving the utilization of precipitation resources in apple orchards on the Weibei dryland. [Methods] This study used conventional organic mulching management as the control（CK）, and investigated the impact of RCIC on orchard soil moisture and its deficit status, apple tree root growth, photosynthetic characteristics, apple yield, and rainfall use efficiency（RUE）. [Results] RCIC significantly promoted soil water infiltration into deeper layers through a "surface interception-deep infiltration" mechanism. The effective infiltration depth reached 80 cm, and the main water use layer shifted from 20-40 cm in CK to 40-60 cm under RCIC. Compared with CK, the average water storage in the 0-80 cm soil layer increased by 14.71% in 2021 and 8.57%（p＜0.01） in 2022. During the drought period in 2022, RCIC reduced water deficit（W_D） in the 40-80 cm soil layer by 3.09%, overcoming the spatial limitation of surface-level irrigation in traditional systems. After RCIC implementation, the fine root length density in the 0-100 cm soil layer increased by 21.3% to 25.8%, and photosynthetic water use efficiency（WUE） improved by 24.01% to 80.49%（p＜0.01）. The apple yield and RUE during 2021-2022 were significantly increased by 14.1% to 16.64%（p＜0.05） compared to CK. [Conclusion] RCIC enables precipitation in apple orchards to converge, accumulate, infiltrate shallowly and deeply, and redistribute along tree rows during the rainy season. This process compensates for deep soil moisture loss and promotes root extension. It further enhances net photosynthetic rate, rainfall utilization efficiency, and yield. These findings provide theoretical and data support for the coordinated and efficient use of both precipitation and irrigation water resources in rain-fed orchard systems.

Abstract:[Objective] The objective of this study is to solve the problems of unscientific destruction of soil structure, deterioration of soil quality and decline of crop yield in the semi-arid area of the Loess Plateau. The effects of tillage methods and nitrogen application rates on the stability of soil aggregates and maize yield were studied, in order to explore tillage methods and nitrogen application rates that can improve soil quality in arid areas, and provide technical and theoretical support for sustainable production of maize in dry farming. [Methods] Four tillage methods [rotary tillage（RT）, ploughing（CT）, no-till（NT）, subsoiling tillage（SS）] and two nitrogen application rates [N1（200 kg/hm²）, N2（300 kg/hm²）] on soil water stability aggregate content, stability index and maize yield in 0-50 cm soil layers.[Results] Compared with RT and CT, SS and NT significantly increased by 8.3%, 10.7%, 16.7% and 19.3%, respectively, and N1 was significantly higher than N2. Tillage and nitrogen application significantly affected the content of aggregates in different soil layers, NT increased the content of aggregates with a particle size of ＞5 mmeach soil layer at 0-50 cm, decreased the content of aggregates with a particle size of ＜0.25 mm, increased the content of aggregates with a particle size of 1-2 and 0.25-1 mm in soil layers of 5-10 cm with SS, and increased the content of aggregates with a particle size of 0.25-1 mm in soil layers of 0-5 and 5-10 cm in N1 treatment by 15.1 and 9.1 percentage points, respectively, compared with N2. NT can increase the average weight diameter（MWD） and geometric average diameter（GMD） of aggregates in each soil layer at 0-50 cm, and reduce the aggregation fragmentation rate（PAD）. The effects of SS on MWD, GMD and PAD showed the characteristics of soil strata differentiation. The nitrogen application rate only affected the PAD of 10-30 and 30-50 cm soil layers, and N1 was significantly lower than that of N2 by 4.4% and 3.3%, respectively. Correlation analysis showed that soil volume quality and soil porosity were significantly negatively correlated with MWD and GMD, while maize yield was significantly positively correlated with GMD and MWD.[Conclusion] Under the experimental conditions, the application of N 200 kg/hm² combined with no tillage and subsoiling tillage can significantly improve the stability of soil agglomeration, improve soil structure and increase yield, and it is recommended to apply it in production.

Abstract:[Objective] This study aimed to investigate the effects of moss crusts on the spatial distribution characteristics of soil erosion and deposition on slopes on the Loess Plateau. [Methods] Simulated rainfall experiments integrated with Structure-from-Motion（SfM） photogrammetry were conducted to analyze the spatial distribution of soil erosion and deposition on slopes with varying moss crust coverage levels（bare soil, 20%, 40%, 60% and 80%）. [Results] 1) Moss crusts significantly reduced soil erosion rates by 23.34%, 37.01%, 51.01% and 71.26%, respectively, compared to bare slopes. 2) The primary erosion zones on moss crust-covered slopes were located in the bare patches of the upper and middle part of the slopes, while deposition predominantly occurred in moss crust-covered regions at the base of the slopes. 3) Compared to bare slopes, moss crusts effectively reduced the area of slope erosion by 14.69%, 42.97%, 58.69% and 82.25%, respectively, and reduced erosion depth by 4 mm. 4) Moss crusts caused localized deposition on the slopes, with depositional areas accounting for 0.21%, 8.41%, 4.53% and 0.41% for the moss crust-covered slopes under respective coverage, and the thickness of the deposition increased by 2 mm compared to bare slopes. 5) Moss crust significantly influenced the spatial distribution characteristics of erosion-deposition on slopes through surface coverage and sediment interception. [Conclusion] The results can advance our understanding of the spatial distribution of soil erosion on the biocrust-covered slopes on the Loess Plateau, and provide a scientific foundation for further analysis of the mechanisms underlying the soil erosion process on the moss-covered slopes, as well as for formulating and implementing effective soil and water conservation management measures.

Abstract:[Objective] A comprehensive evaluation is carried out on the long-term variations in landscape pattern indices and changes in current habitat quality in the Xiliugou basin, aiming to provide a theoretical basis for formulating effective ecological restoration strategies and promoting the sustainable development of the basin’s ecological economy. [Methods] Five time points（2000, 2005, 2010, 2015 and 2020） were selected to analyze the landscape pattern indices, current habitat quality, and their driving factors in the Xiliugou Basin using Fragstats, the InVEST model, and the geodetector.[Results] 1) From 2000 to 2020, the landscape in the study area demonstrated a clear trend of aggregation and homogenization. This was primarily reflected in the expansion of grasslands, a reduction in fragmentation, lower edge complexity, and decreased diversity. A temporary increase in fragmentation in 2015 reflected phased human disturbance. 2) The study area was dominated by regions with relatively high habitat quality, accounting for approximately 60% of the total area. From 2000 to 2020, the difference in area between habitat quality improvement zones and degradation zones gradually decreased, with degradation trends intensifying after 2010. Spatially, higher-quality habitats were primarily located in the downstream region, while lower-quality zones were concentrated in the northern midstream region, namely the Kubuqi Desert. Medium-quality habitats were distributed in a fragmented pattern in the upstream region. 3) Land use type was the dominant factor influencing the spatial differences in habitat quality. Its influence was strengthened by interactions with elevation, vegetation cover, and climatic factors such as annual mean temperature. A significant enhancement in the explanatory power for spatial differentiation was observed when both natural and human factors acted jointly. [Conclusion] A systematic analysis of the current status of the ecological environment and its driving factors in the Xiliugou basin clarified the spatial distribution of habitat quality and identified the key factors driving changes in ecological quality. This provides a theoretical basis for identifying priority areas and developing strategies for ecological restoration in the basin.

Abstract:[Objective] To reveal the hydrological regimes and trends of runoff and sediment discharge in the mainstream of the upper reaches of the Yellow River. [Methods] Using the non-parametric Mann-Kendall test, Pettitt′s test, and Morlet wavelet transform, this study analyzed the trends, abrupt changes, and periodic variations of runoff and sediment discharge in the upper mainstream of the Yellow River from 1950 to 2020. [Results] The annual sediment discharge varied significantly at different stations in the upper mainstream of the Yellow River compared to the annual runoff. The maximum annual average runoff and sediment discharge were observed at Xiaheyan Station, reaching 304.74×10⁸ m³ and 1.13×10⁸ t, respectively, while the minimum values were recorded at Tangnaihai Station, being 203.67×10⁸ m³ and 0.12×10⁸ t, respectively. The annual runoff was mainly concentrated in the Xiaochuan-Shizuishan section, while the annual sediment discharge was mainly distributed in the Xiaheyan-Toudaoguai section. Both annual runoff and sediment discharge at all stations showed a decreasing trend and had significantly decreased from 1990 to 2020. Notable abnormal changes in runoff and sediment discharge were observed in 1968, 1985 and 1986. There were 2-5 obvious peaks in runoff and sediment discharge as shown by wavelet analysis, indicating that there were multi-time scale characteristics in the evolution process of runoff and sediment discharge. The fluctuation amplitude of wavelet coefficients of runoff and sediment discharge showed a continuous decreasing trend, and the periodic characteristics of both the runoff and sediment discharge also exhibit a weakening tendency. In the future, both runoff and sediment discharge are expected to continue decreasing, with the decreasing trend of sediment discharge being more significant. [Conclusion] The results highlight that human interventions, such as the construction of cascade reservoir groups, comprehensive watershed management measures, and the continuous increase in water withdrawal outside the river channel, have become the dominant driving factors for the variations of runoff and sediment discharge processes in the upper mainstream of the Yellow River. The findings of this research will offer valuable insights for guiding watershed water resources planning and efficient management in the upper reaches of the Yellow River.

Abstract:[Objective] This study aimed to establish the criteria for erosive rainfall events under different soil and water conservation measures in runoff plots, and to explore the influencing factors of these criteria. [Methods] Using observational data on rainfall, runoff and sediment yield from 17 standard runoff plots at the Qiaozigou experimental site in the Luoyugou watershed of Tianshui, Gansu Province, in the Loess Hilly Region from 2011 to 2020, frequency analysis and sediment connectivity（IC） assessments were employed to evaluate the criteria for erosive rainfall and their influencing factors under various soil and water conservation measures. [Results] Soil and water conservation measures reduced runoff and sediment yield across different plots. Compared to the control plot, grassland and woodland plots exhibited the most significant reductions in runoff（ 80.39%） and sediment yield（79.78%）. The reduction rate for cropland（47.41%） was notably lower than that for grassland and woodland. Conservation measures elevated the criteria for erosive rainfall, which was ranked in the order of control plot（ 11.62 mm）＜cropland（13.76 mm）＜grassland（18.08 mm）＜woodland（18.26 mm）. The criteria for erosive rainfall showed a negative correlation with the number of runoff events, the connectivity index（IC） and the runoff coefficient, with higher criteria associated with lower IC values, smaller runoff coefficients and weaker hydrological connectivity. [Conclusion] Following soil and water conservation, the hydrological connectivity of slopes decreased, the amount of erosive rainfall reduced, the runoff capacity significantly declined and the criteria for erosive rainfall notably increased, with variations among different measures. This study elucidates the criteria for erosive rainfall on slopes under various soil and water conservation measures and their influencing factors, providing a reference for monitoring soil and water loss on slopes on the Loess Plateau.

Abstract:[Objective] This study aimed to investigate the changing patterns of soluble nitrogen（N） fractions in alpine wetland meadow soils in the context of long-term global nitrogen deposition. [Methods] Taking the Gahai wetland meadow soil at the northeastern edge of the Qinghai-Xizangan Plateau as the research object, the characteristics of soil soluble N fractions in response to N addition were investigated, relying on the experimental platforms that had been treated with N addition for three years [CK（no added N）, N1（4.14 g NH₄ NO₃） and N2（6.12 g NH₄ NO₃）]. [Results] 1) Compared to CK, the N1 treatment significantly increased the mass fraction of soil nitrate-nitrogen（NO₃^--N）（ 15.76%）, while the N2 treatment significantly increased the mass fraction of soil ammonium-nitrogen（NH₄⁺-N）（19.19%）（p＜0.05）. 2) Under different N addition treatments, soil soluble organic nitrogen（SON） density was the highest（106.14 kg/hm²）, followed by NO₃^--N density（92.41 kg/hm²）, and NH₄⁺-N density was the lowest（91.18 kg/hm²）. 3) The changes in the proportion of NO₃^--N, NH₄⁺-N and SON densities to total nitrogen（TN） were more significant under the N1 treatment than that under the N2 treatment, indicating a better enhancement of soil N supply potential of the N1 treatment. 4) PCA analysis showed that N addition had an important effect on the characteristics of soil soluble N components in the alpine wetland meadow of Gahai. Soil soluble N fractions under the N1 treatment were mainly regulated by TN, while under the N2 treatment, they were mainly regulated by soil organic carbon and microbial biomass carbon. [Conclusion] Low N treatment can increase the soluble N fractions of alpine wetland meadow and promote soil N transformation, while high N addition can have the opposite effect.

Abstract:[Objective] To reveal the coordinated evolution patterns and obstacle factors of the water-energy-food（WEF） nexus in the middle reaches of the Yellow River basin. [Methods] An evaluation index system for the WEF nexus was established. The entropy weight method was used to calculate the weights of the indicators, and the coordinated evolution characteristics of the system from 2010 to 2021 were analyzed. A diagnostic model of obstacle degree was applied to identify the key constraining factors.[Results] The temporal evolution of the WEF nexus in the study area exhibited three typical stages, with 2017 identified as a key turning point. The sustainability index shifted from steady growth to rapid improvement, with the regional maximum increasing from 0.56 to 0.74. The spatial pattern transformed from a "concave" distribution in 2010 to a "convex" one in 2020, reflecting a regional development trend of "prominent advantages in Shaanxi, steady improvement in Shanxi, and relative lag in Inner Mongolia". Baoji City, in particular, achieved a remarkable 117.60% increase in its sustainability index, whereas traditional industrial cities such as Taiyuan and Baotou experienced negative growth. Obstacle factors demonstrated significant regional disparities and dynamic variations. In Inner Mongolia, the primary constraints shifted from industrial chemical oxygen demand（COD） emissions（9.64%） to dual limitations of agricultural irrigation water use and energy consumption. In Shaanxi, the obstacle degree of industrial COD emissions significantly decreased（from 11.71% to 0.26%）, while the constraint posed by energy consumption increased（10.13%）. In Shanxi, the obstacle degree of industrial COD emissions sharply dropped（from 13.90% to 0.15%）. [Conclusion] The coordinated development of the WEF nexus is dynamically regulated by resource use efficiency and industrial structure. The proposed method for identifying region-specific obstacle factors can provide decision-making support for ecological conservation and optimized resource allocation in the Yellow River Basin.

Abstract:[Objective] To investigate the spatiotemporal evolution patterns and driving effects of net carbon sink in Ningxia’s farmland ecosystems under the "dual carbon" goals. [Methods] Taking the region’s farmland ecosystem as the research object and based on the carbon emission factor method released by the Intergovernmental Panel on Climate Change（IPCC）, a calculation system for net carbon sink in farmland was established by measuring the difference between carbon absorption during the crop growth period and carbon emissions from agricultural production activities. The net carbon sink volume and net carbon sink intensity in Ningxia from 2003 to 2022 were calculated. ArcGIS visualization, center of gravity shift model, and the standard deviation ellipse were employed to characterize the spatiotemporal characteristics of net carbon sink in farmland. Furthermore, the Logarithmic Mean Divisia Index（LMDI） model was applied to identify the main driving factors of net carbon sink in Ningxia’s farmland. [Results] 1) In terms of temporal characteristics, total net carbon sink in Ningxia’s farmland showed an overall increase during the study period, increasing from 3.38×10⁶ t in 2003 to 7.56×10⁶ t in 2022. Additionally, the net carbon sink intensity exhibited a rising trend, rising from 2.55 t/hm² in 2003 to 6.35 t/hm² in 2022. 2) For spatial characteristics, the distribution of net carbon sink in Ningxia’s farmland across counties shifted from a pattern of "higher in the northwest and lower in the southeast" to "higher in the north and lower in the south". The center of gravity of net carbon sink in farmland moved from Lingwu City in Yinchuan to Hongsibao district in Wuzhong, with a shift distance of 40.15 km. 3) In terms of net carbon sink sources, chemical fertilizer application was the primary source of carbon emissions in Ningxia’s farmland ecosystem, accounting for 36.06% of the total. Corn was the main contributor to carbon absorption, representing 50.90% of total carbon absorption. 4) Net carbon sink efficiency in farmland and agricultural labor were negative driving factors for net carbon sink in Ningxia’s farmland, whereas economic development level, urbanization level, and agricultural industrial structure were positive driving factors. [Conclusion] Farmland ecosystems in Ningxia exhibit significant spatiotemporal differentiation in net carbon sink, with the carbon sink effect strengthening over time. Optimizing both agricultural industrial structure and crop planting structure can effectively strengthen carbon sink capacity of farmland. This study provides theoretical support for ecological carbon sink management in arid regions, offering strategic guidance for developing carbon emission reduction policies and achieving "dual carbon" goals in northwest China.