• Good News: 243 Papers from the 'Journal of Soil and Water Conservation' Included in CNKI's High-Impact Paper List
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    Volume 38,  2024 Issue 2
    • LI Taotao, LIU Yijian, YE Jiali, WANG Shiwen, YIN Lina, DENG Xiping, SHAN Lun

      2024,38(2):1-12,338, DOI: 10.13870/j.cnki.stbcxb.2024.02.002

      Abstract:

      [Objective] Crops often suffer from interval drought and rehydration (rainfall or irrigation) during the whole growth period, especially in arid and semi-arid areas. Under drought stress, the growth and development of crops are inhibited, and the yield is reduced; meanwhile, the plants drought tolerance will be induced. In order to compensate loss of yield or growth induced by drought stress, crop often shows compensatory after rehydration, which produces compensation or even over compensation effect on yield. The compensation effect of post drought is the result of crop’s positive response to drought stress and compensatory growth after rehydration. It can effectively improve crop yield and water use efficiency in crop production in arid areas. [Methods] Source sink relationship is widely used to explain the crop yield formation, and regulating the source sink relationship is one of key way to improve crop yield. The compensation effect of post drought is highly related to the source sink response of crops. Based on the current research progress, this paper tries to explain the compensation effect of post drought in source and sink way. [Results] Under the drought stress, in the source, the stomata were closed, photosynthesis was decreased and soluble carbohydrate accumulation was increased, while sink activity was often increased. After rehydration, the metabolism of soluble carbohydrate in the source (leaf) was enhanced, which enhanced the photosynthesis and the ability of carbohydrate synthesis; meanwhile, the sink activity (grain) was maintained at a high level, and the rate of assimilate unloading and accumulation was accelerated; the assimilate in the flow remained at a high level. During this process, the activities of sucrose invertase (INV), cell wall invertase (CW-INV) and fructan exohydrolases (1-FEH w3) play important roles in the source sink response to the compensation effect of post-drought. [Conclusion] This paper integrated the mechanism of compensation effect of post drought in the perspective of source sink relationship, which provides a theoretical basis for understanding the mechanism of compensation effect of post drought and improving crop water efficient in arid areas.

    • XIE Xiangrong, CHEN Zhengfa, ZHU Zhenyan, XU Xingqian, YAN Kai, LI Bo, DUAN Qingsong, LI Shufang, ZHANG Chuan

      2024,38(2):13-28,196, DOI: 10.13870/j.cnki.stbcxb.2024.02.017

      Abstract:

      [Objective] In order to investigate the mechanism of mechanical effect of root-soil complex and the application of modeling method. [Methods] The concept and connotation of root-soil complex, the principle of mechanical effect and mechanical model of root-soil complex, advantages and disadvantages as well as the scope of application were summarized and analyzed by using literature analysis method and comparative analysis method. [Results] (1) The root-soil complex was a composite whole of mechanical coupling effect between root system and soil body, and the root system was intertwined in soil playing a reinforced role. (2) The mechanical relationship between root system and soil body was essentially the result of soil mechanical, hydraulic and composite mechanical properties of root-soil complex. The soil mechanical and hydraulic properties focused on the influence of roots on the soil and the influence of water on the soil and root system respectively, and the composite mechanical properties focused on the direct influence of soil properties on the properties and structure of plant roots, so that the mechanical relationship between roots and soil was in a dynamic balance through the three. (3) The study of the composite mechanical model of the root-soil complex was slightly less than that of the soil mechanical and hydraulic model, which were based on quantitative parameters and measure the soil consolidation effect by comparing parameters. However, the composite mechanical properties involves both soil and hydraulic properties, which was a comprehensive consideration and should be the key research direction in the future. [Conclusion] In-depth research was needed in the future to investigate the effects of freeze-thaw cycle, dry-wet alternation and dry-hot cycle on root and soil interaction in different regions, the shear strength of multi-type plant mixtures, the influence mechanism of chemical and microbial effects on soil-water propertiess and the construction of composite models need to be further studied. This study can provide important theoretical value and engineering reference for vegetation restoration, soil and water conservation and sustainable development in ecologically fragile areas.

    • LI Juan, SHAO Ming, LI Fahu, ZHAO Han

      2024,38(2):29-37,46, DOI: 10.13870/j.cnki.stbcxb.2024.02.005

      Abstract:

      [Objective] Soil and water loss control is the key to the prevention and control of rocky desertification in karst areas, so the mechanism of soil and water loss and its influencing factors are explored. [Methods] The effects of water pressure (0.3, 1.3, 2.3, and 5.5 m water head height), karst fissure width (0.25, 0.5, 0.75, and 1.0 cm), and soil aggregate size (0~1.0, 1.0~2.0, 2.0~5.0, and 0~5.0 mm) on the process of soil and water leakage in the karst peak-cluster depression were studied through laboratory simulation experiment. [Results] The greater the water pressure and the fissure width were, the smaller the soil aggregate size was, or the absence of certain soil particle groups, the more easily the overlying soil layer was broken down taking approximately 2 to 20 minutes. After the soil layer was broken down, the water leakage rate surged rapidly before stabilizing, while the soil leakage rate peaked and then settled. The rates and cumulative amounts of soil and water leakage from the disrupted soil layer were significantly greater than that of the unbroken one. The cumulative amounts of water and soil leakage increased with the increased water pressure or fissure width. When fissure width was 0.25, 0.50, 0.75, and 1.00 cm, the cumulative amount of water leakage at 1.3 to 5.5 m water pressures was 1.2 to 13.2, 2.4 to 131.0, 2.1 to 167.3, and 75.8 to 141.9 times greater than that at 0.3 m one, respectively. The cumulative soil leakage diminished notably with larger soil aggregate sizes. The absence of larger aggregates led to the decrease of soil leakage with the increase of fissure width but the opposite was true for soils lacking smaller aggregates. When fissure width was 0.25, 0.50, 0.75, and 1.00 cm, the cumulative amounts of soil leakage from 1.0 to 2.0 and 2.0 to 5.0 mm aggregate particle groups were decreased by 98.4% and 99.1%, 46.3% and 83.7%, 43.2% and 74.0% as well as 41.1% and 27.1%, respectively, compared with that of 0 to 1.0 mm one. [Conclusion] The stability of the overlying soil layer plays a pivotal role on the process of soil and water loss in peak-cluster depression, and hydraulic conditions, soil properties, and the degree of karst fissure development critically influence this stability.

    • LI Siyao, MENG Zhongju, QI Shuai

      2024,38(2):38-46, DOI: 10.13870/j.cnki.stbcxb.2024.02.022

      Abstract:

      [Objective] In order to explore the typical surface wind erosion process of the dry lake basin and the mechanism of the formation of saline-alkali dust storm. [Methods] Taking the Chagannaoer dry salt lake in Abaga Banner of Xilin Gol League as the research object, four different surface types (crust surface, broken surface, activated surface and desertification surface) were selected according to the dynamic evolution process of salt lake surface from the lake center to the lake shore. The characteristics of soil particle size distribution, wind speed profile and sediment transport law near the surface from the lake center to the lake shore were analyzed. [Results] (1) Extending from the center of the lake to the shore of the lake, the grain size of 0—2 cm sediment on the surface showed a trend of gradually thickening, and the clay and silt were the main particles. (2) The wind speed from the center of the dry salt lake to the shore of the lake showed a decreasing trend. Wind speed profiles of different surfaces generally followed the logarithmic distribution of Karman’s velocity, and the fitting effect was good (R2>0.90). (3) The amount of sediment transport on the broken surface was the highest, which was about 50 times that of the crust surface, and the sediment transport rate on the crust surface showed a linear law with the change of height due to limited dust supply (R2=0.80), and the sediment transport rate on the other three surfaces showed an exponential function with the change of height (R2>0.97). (4) Near the surface at a height of 0 to 50 cm, the average particle size of sand particles carried in the wind-sand flow ranges from 2 to 8 μm, which falled under the category of silt, with poor sorting. Skewness was predominantly negative, while kurtosis was mainly medium and sharp. [Conclusion] On the whole, the wind erosion effect on the broken surface was the strongest, and the wind erosion effect on the crust surface was the weakest. The wind erosion effect in this area can be weakened by increasing the critical starting wind speed threshold of sand particles and the coverage of underlying surface.

    • DING Guihui, REN Zhongzheng, HU Wei, CHEN Yuan, ZHANG Xingyi

      2024,38(2):47-56, DOI: 10.13870/j.cnki.stbcxb.2024.02.019

      Abstract:

      [Objective] Rainfall is the driving force of hydraulic erosion in black soil sloping farmland. It is of great significance to study soil erosion characteristics under natural rainfall conditions for soil erosion control. [Methods] Based on 43 erosive rainfall events observed at different ridge-row runoff plots (3°, 5° and 7°) along the slope in Guangrong Small Watershed, Hailun City, Heilongjiang Province during 2021—2022, K-Mean clustering method was used to compare the characteristics of runoff and sediment transport under different rain patterns and slopes, and the influencing factors on runoff and sediment transport were discussed. [Results] The rainfall of short duration, heavy rain and light rainfall (rain type 3) is the main one, followed by the rainfall of medium duration, medium rain intensity and medium rainfall (rain type 2), and the rainfall of long duration, light rain intensity and heavy rainfall (rain type 1) rarely occurs. Under the same rain pattern, the cumulative runoff depth and sediment transport increased with the increase of slope. Under the same slope, different rainfall types have different responses to cumulative runoff depth. Overall, rainfall type 3 has the highest contribution (50.90%~57.90%), rainfall type 2 has the second contribution (37.60%~44.10%), and rainfall type 1 has the lowest. In the event of rain type 2, rainfall erosivity and slope have direct influence on runoff depth, and runoff depth and slope have direct influence on sediment transport. In the event of rain type 3, rainfall erosivity affects runoff depth and then sediment transport through direct and indirect effects. [Conclusion] For all rainfall-type events, rainfall erosivity and slope are the main controlling factors affecting the runoff depth, and the runoff depth and slope are the main controlling factors affecting the sediment transport.

    • GENG Huajie, ZHENG Fenli, ZHAO Luyou, WANG Lun, ZHAO Ting, QIN Qishan, AN Xiaobing

      2024,38(2):57-67,75, DOI: 10.13870/j.cnki.stbcxb.2024.02.004

      Abstract:

      [Objective] In order to investigate the effects of rainfall intensity, inflow rate and slope gradient on hillslope ephemeral gully erosion and implement precise soil and water conservation measures. [Methods] This research established two rainfall intensities (50 and 100 mm/h) and two slope gradients (3° and 7°), and five inflow rates under four combinations of two rainfall intensities and two slope gradients to assess the influences of rainfall intensity, inflow rate, slope gradient and their interaction on slope soil erosion with ephemeral gully, and to quantify the contribution of ephemeral gully erosion to slope erosion. [Results] (1) The impact of slope gradient and inflow rate on slope soil erosion was greater than that of rainfall intensity. Under the five inflow rates, when the rainfall intensity increased from 50 mm/h to 100 mm/h, the slope erosion on the slopes of 3° and 7° increased by 52.3%~81.8% and 29.4%~88.4%, respectively; when the slope gradient increased from 3° to 7°, the slope erosion increased by 114.3%~395.5% and 130.0%~320.9%, respectively; when the inflow rate increased from 15 L/min to 75 L/min, the slope erosion increased by 4.6~13.5 times. The increase of inflow rate aggravated slope gradient influence on slope erosion while weakened rainfall intensity impacts on slope erosion. (2) The combined effects of rainfall intensity, inflow rate, and slope gradient, and inflow rate-slope gradient interactions on slope erosion were the larger impact, followed by the rainfall intensity-inflow rate interaction, and the interplay between rainfall intensity and slope gradient had the lowest impact. Ephemeral gully erosion accounted for over 85% of total slope erosion under various experimental conditions, which increased with inflow rate and slope gradient. (4) The slope erosion rates a positive correlation existed with the flow velocity, shear stress and stream power. Conversely, a negative correlation was observed with the friction coefficient. Among the parameters, the correlation between slope erosion rate and stream power was best. [Conclusion] The research results provide a scientific basis for the development of ephemeral gully erosion prediction model, the separation of ephemeral gully erosion contribution and the study of ephemeral gully erosion mechanism based on erosion dynamic factors and topographic factors and their interaction.

    • ZHANG Zhuanmin, WANG Bin, RAO Wei, WANG Wengang

      2024,38(2):68-75, DOI: 10.13870/j.cnki.stbcxb.2024.02.015

      Abstract:

      [Objective] To investigate the influence of rainfall energy and initial moisture content on the mechanism of soil aggregate splashing erosion. [Methods] The typical cultivated black soil in northeast China was selected as the research object. Artificial simulated rainfall experiments were conducted to explore the splashing erosion characteristics of soil aggregates with varying initial moisture content, rainfall energy, and initial particle size of aggregates. [Results] (1) The splash erosion of the four kinds of black soil aggregates with initial particle size was highest when the initial soil moisture level was 4%, and the splash erosion of the aggregates with an initial particle size <0.25 mm was 1.21 to 5.50 times that of the aggregates with different particle sizes under the same rainfall energy conditions. Furthermore, as the initial soil moisture increased, the splash erosion of the aggregates within each particle size group decreased initially, but increased when the initial soil moisture surpassed 25%. (2) The splash erosion of four initial particle size black soil aggregates increased with the increase of higher rainfall energy. When the rainfall energy reached 909 J/(m2·h) (equivalent to 5 m), the splash erosion of the different-sized black soil aggregates increased by 15.37 to 20.70 (<0.25 mm), 52.30 to 417.60 times (0.25~1 mm), 51.58~359.36 times (1~3 mm), 68.73~777.99 times (3~5 mm), respectively. Notably, a clear threshold was observed for splash erosion of aggregates with different initial particle size. When the rainfall energy exceeded 529 J/(m2·h) (equivalent to 2 m), there was a significant difference in splash erosion among different rainfall energy gradient. (3) The analysis highlighted that rainfall energy was the primary factor affecting splash erosion. It exhibited a direct effect with a correlation coefficient of 0.811, demonstrating a significant positive influence. Conversely, the direct effects of initial soil moisture and initial particle size of aggregates were significantly negative, with correlation coefficients of 0.193 and 0.352, respectively. [Conclusion] The research findings can provide a scientific basis for investigating the mechanisms of slope soil erosion in the black soil regions of Northeast China, as well as for establishing process-based models for soil erosion.

    • CHEN Meng'en, WEI Xing, ZHOU Yulin, SHI Ruibo, LI Yineng

      2024,38(2):76-84,245, DOI: 10.13870/j.cnki.stbcxb.2024.02.038

      Abstract:

      [Objective] Runoff changes under the combined influence of climate change and human activities. Exploring the temporal and spatial evolution of runoff and its causes has important guiding significance for the scientific operation of reservoirs and the sustainable use of water resources. [Methods] Based on the meteorological and hydrological data of the Wanzhou section of the Three Gorges Reservoir Area from 1960 to 2019, Mann-Kendall trend test, Pettitt mutation analysis and wavelet analysis were used to analyze the spatial and temporal evolution characteristics of runoff before and after the impoundment in the Three Gorges Reservoir Area. Finally, two Budyko hydrothermal coupling equilibrium equations were used to quantitatively calculate the influence rate of climate change and human activities on runoff change. [Results] (1) The annual runoff in the study area showed a significant downward trend (|z|>2.58), with the inflection point appearing in 2003 (the impoundment year of the Three Gorges Reservoir Area), after which the annual distribution was more uniform. (2) Compared to the period before impoundment, the contribution rates of climate change and human activities to the reduction of annual runoff in the study area after impoundment were 27.9% to 29.2% and 70.8% to 72.1%, respectively. (3) Human activities primarily influence the annual runoff of the basin by altering the type of land use and the construction of water conservation projects. [Conclusion] This study quantitatively describes the impact of human activities on runoff changes, and provides the oretical support for the next stage of water resources management in the Three Gorges Reservoir Area.

    • ZHANG Zhuopei, NIU Jianzhi, FAN Dengxing, ZHAO Chunguang, MIAO Yubo, DU Zhou, YANG Zhiyong

      2024,38(2):85-96, DOI: 10.13870/j.cnki.stbcxb.2024.02.014

      Abstract:

      [Objective] To reveal the spatial and temporal evolution characteristics of soil water erosion in the middle reaches of the Yellow River in the rich and coarse sediment area from 2000 to 2020, and analyze its dynamic driving force. [Methods] Based on the RUSLE model, the annual soil water erosion modulus in the rich and coarse sediment area was calculated, and the variation characteristics of soil water erosion intensity in 2000, 2005, 2010, 2015, and 2020 were analyzed. The spatial-temporal characteristics of soil water erosion modulus were explored by using the Sen+MK trend analysis method combined with the Hurst index, and the factor probing in the parameter-optimal geographical detector with the interactive probing were used to quantify the explanatory power of six factors, namely average annual precipitation, elevation, slope, vegetation cover, land use/cover type, and soil type, on the spatial distribution of soil water erosion. [Results] (1) The area of moderate, intense, extremely intense and severe erosion in the rich and coarse sediment area decreased by 48.09%, 77.93%, 83.01%, and 36.13%, respectively, and the area of slight and mild erosion increased by 46.22% and 0.33%, respectively, in the five periods from 2000 to 2020. At the present stage, the sandy and coarse sandy area was dominated by slight and mild erosion, and the proportion of the two was 62.49% and 42.07% respectively. (2) The overall inter-annual change of soil water erosion modulus in the rich and coarse sediment area showed a fluctuating and significant downward trend, from 2 214.89 t/(km2·a) in 2000 to 1 169.44 t/(km2·a) in 2020. The spatial variation trend of soil water erosion modulus in the rich and coarse sediment area from 2000 to 2020 was mainly in a decreasing state, accounting for 76.13% of the total area, and would continue to be in a decreasing state in the future, with an area share of 62.50%. (3) The explanatory power of the interactions among the six factors was greater than that of single factor, and it was mainly manifested as nonlinear enhancement and double-factor enhancement; soil water erosion in the rich and coarse sediment area was dominated by precipitation and land use/cover in 2000—2005, and by vegetation cover and land use/cover in 2010—2020. [Conclusion] Soil water erosion condition in the rich and coarse sediment area will be improved continuously from 2000 to 2020; in the future, the soil water erosion modulus of 62.50% of the regions will continue to decline or decline in the future, but there is still a potential risk of increase in 20.44% of the area; the land use/cover pattern has changed by the project of returning farmland to forests and grassland, which made the soil water erosion in the rich and coarse sediment area. The driving force of soil water erosion in the rich and coarse sediment area changes dynamically; the slope factor needs to be fully considered when optimizing the land use/cover pattern for the prevention and control of soil water erosion in the rich and coarse sediment area in the future.

    • LIAO Jun, JIAO Juying, YAN Zeng, LI Jianjun, ZHANG Shijie

      2024,38(2):97-108, DOI: 10.13870/j.cnki.stbcxb.2024.02.001

      Abstract:

      [Objective] To explore the effectiveness of the Revised Universal Soil Loss Equation (RUSLE) model in simulating soil erosion on slope surfaces during vegetation restoration in the Loess Plateau. [Methods] This study utilized rainfall-runoff and sediment data from ten runoff plots in Ansai Fangta small watershed in northern Shaanxi Province during 2016—2022. Utilizing various commonly used algorithms for RUSLE model factors specific to the Loess Plateau, a total of 144 combinations of factors were simulated to estimate soil erosion on restored slopes. The Nash-Sutcliffe efficiency coefficient (NSE) and root mean square error (RMSE) were used to evaluate the effectiveness of the model simulations. [Results] The results indicated that the simulated soil erosion on restored slopes using the 144 factor combinations ranged from -38.47 to 0.19 for NSE and from 1.92 to 12.65 t/(hm2·a) for RMSE, suggesting limited model performance. The selected algorithms for RUSLE model factors appeared to be inadequate for assessing soil erosion on slopes undergoing vegetation restoration. Further improvements are needed for the individual factors within the RUSLE model. When applying RUSLE model to simulate soil erosion on restored slopes in the Loess Plateau, it is recommended to utilize data with high temporal resolution to reduce errors in calculating the R-factor, and comprehensively consider the effects of soil physical and chemical properties such as soil organic matter content, soil particle size and aggregate structure and bulk density on K-factor, and the the effects of vegetation coverage, vegetation height, litter, and biological crust and C-factor, full consider to slopes steeper than 10° in refining the LS-factor. [Conclusion] The RUSLE model is not well-suited for simulating soil erosion in the context of vegetation restoration on abandoned slopes in the Loess Plateau.This study provides some reference for the research and development of soil erosion model and the application of RUSLE model on the slope of vegetation restoration in the Loess Plateau.

    • JIA Chenyang, LIU Hongyuan, YU Yue, MA Qianhong, KE Qihua, ZHANG Keli

      2024,38(2):109-117,325, DOI: 10.13870/j.cnki.stbcxb.2024.02.028

      Abstract:

      [Objective] To evaluate the contribution of freeze-thaw cycle (FTCs) to gully erosion by measuring the collapse volume of gully wall collapse during FTCs. [Methods] From 2016 to 2018, a total of 463 collapse points in 36 gullies were selected for field investigation. Based on the investigation results, there were two types of wall collapse: massive collapse and loose accumulation. The morphology parameters of two kinds of accumulations were measured at each collapse point, including the volume of the collapsed soil, the width and depth of the gull coross-section, and the shear force and hardness of soil of the corresponding gully wall soil. [Results] (1) The average collapse strength of gully wall collapse caused by FTCs during the three-year study period is 16.12 m3/(km·a). The two types of collapse occurred randomly within the gully, and the single point freeze-thaw collapse mainly concentrated in 0~3 m3, but the amount of soil caused by massive collapse was larger. (2) The transverse width and depth of the gully were the main factors affecting the collapse of the gully wall, and the collapse amount increased with the increase of the width-depth ratio. When the width-depth ratio>2.71, the collapse amount increased rapidly. (3) The amount of gully collapse was closely related to the shear force and hardness of the soil on the gully wall. [Conclusion] The freeze-thaw collapse of the gully wall was closely related to the width and depth of the gully cross-section, the freeze-thaw collapse accounted for 3.28% to 23.68% of the sediment yield of the gully erosion, and its influence was equivalent to that of the headward erosion of gully head. The research results provide data support for quantitatively evaluating the contribution of FTCs to gully erosion.

    • CHANG Zhiyong, YANG Yicui, LU Baopeng, LIU Yan, PEI Chengruo, YANG Chunguang

      2024,38(2):118-125, DOI: 10.13870/j.cnki.stbcxb.2024.02.011

      Abstract:

      [Objective] To reveal the influences of slope gradient and rainfall intensity on the erosion and sediment yield characteristics of the colluvial deposits from Benggang, and to provide a scientific basis for soil and water loss prediction and control of the colluvial deposits in southern Guangxi. [Methods] The indoor experiment of simulated rainfall was carried out to investigate the erosion and sediment yield phocesses of colluvium slope under different slope gradients (15°, 20°, 25°) and rainfall intensities (60, 90, 120 mm/h). [Results] The results showed that the variation processes of the erosion rate of the colluvium were relatively stable, and the erosion rate was mostly lower than 5.0 g/(m2·s), and showed a certain downward trend when the rainfall intensity was 60 mm/h under different slope conditions. While, the erosion rate fluctuated to increase first, and then decreased under the rainfall intensity of 90 to 120 mm/h. The maximum erosion rate during each rainfall increased with the increase of rainfall intensity and slope gradient, and the maximum erosion rate occurred within 0 to 25 min and tended to advance with the increase of slope gradient. The sediment yield amount (from 3.64 to 48.07 kg/m2) increased with the increase of rainfall intensity and slope gradient, and the nonlinear regression result (a power function) between the sediment yield amount and rainfall intensity and slope gradient was better than the linear regression result. The correlation between sediment yield amount and the interaction of slope gradient and rainfall intensity was the most significant and showed a high-significant linear function relationship. [Conclusion] The sensitivity coefficient of the sediment yield amount to rainfall intensity was higher than that to slope gradient, and the influence of rainfall intensity on sediment yield was stronger than slope gradient. gradient Slope drainage measures should be taken in the prevention and control of colluvial deposit erosion.

    • SHI Hailong, ZHANG Linxing, GAN Fengling, PU Junbing, GOU Junfei, LIU Juan

      2024,38(2):126-135, DOI: 10.13870/j.cnki.stbcxb.2024.02.007

      Abstract:

      [Objective] In order to accurately evaluate the soil quality characteristics of the dip/anti-dip erosion slope in the karst trough valley screen out suitable soil quality evaluation methods and explore the obstacle factors limiting soil quality in this area. [Methods] Five typical land use types (forest land, grassland, bare land, corn land, pepper land) were selected as the research objects in Qingmuguan Karst trough Valley of Chongqing, and the minimum data set (MDS) was established by principal component analysis combined with Norm value. The nonlinear soil quality evaluation method and membership function were used to evaluate the soil quality of the diplanti-dip erosion Slope and down-slope in the karst trough valley. [Results] (1) MDS of soil quality evaluation indexes in karst troughs valleys included capillary water capacity, capillary porosity and total phosphorus. (2) According to the nonlinear soil quality evaluation method, the soil quality of anti-dip erosion slope (0.519) was better than that of dip erosion slope (0.451). The soil quality of anti-dip erosion slope forest land was the best (0.653), and that of pepper field was the worst (0.426). (3) The coefficient of determination (R2) of the nonlinear evaluation method was higher than the membership function in the dip erosion slope and the anti-dip erosion slope, so the non-linear scoring model was more suitable for the karst trough valley. (4) There were significant differences in soil quality barrier factors, and only total nitrogen was the common barrier factor. [Conclusion] Appropriately increasing grassland and forest cover can improve soil quality in karst trough and valley area. The results of this study can provide basis for soil quality control and rational fertilization of slope erosion along/against slope in karst trough valley according to local conditions.

    • ZHAO Yunlong, FU Suhua

      2024,38(2):136-146, DOI: 10.13870/j.cnki.stbcxb.2024.02.008

      Abstract:

      [Objective] Slope and slope length are essential topographic factors, and their calculation accuracy directly affects the evaluation accuracy of slope soil erosion model. The high-precision elevation measurement capability of Gaofen-7 satellite has great potential in the accurate extraction of terrain factors, and it is expected that it can be used in the extraction of slope and slope length to achieve accurate expression of terrain. It is necessary to evaluate the accuracy of the results of slope length extraction using the DEM of Gaofen-7 satellite. [Methods] The slope and slope length of DEM generated by Gaofen-7 satellite, 1∶10 000 topographic map and LiDAR images in 4 small basins in Wubu County, Shaanxi Province were extracted by using the terrain factor (LS) calculation tool. Correlation coefficient (r), relative deviation (RE) and absolute deviation were used as evaluation indexes to evaluate the accuracy of extraction of topographic factors by Gaofen-7. [Results] Compared with the slope and slope length of LiDAR and 1∶10 000 topographic map, the average slope extracted by GF-7 was 7.50%~9.02% lower, and the slope length was 1.83%~19.35% larger. However, the area distributions of slope length and slope derived from the three data sources had no significant difference. Comparing the results of slope and slope length, the discrepancy in slope (RE: 16.46%~44.26%) derived from different sources is significantly lower than that (RE: 75.25%~140.87%) was slope length. The discrepancy between different sources was enhanced in gully areas (RE of slope 15.48%~56.63%, slope length: 50.02%~130.79%), while being decreased in inter-gully areas (RE of slope 21.28%~63.61%, RE of slope length 93.01%~192.51%). [Conclusion] It was feasible to obtain areal grading characters of slope or slope length and slope of specified locations using DEMs generated from Gaofen-7 satellite, while the results of slope length for specified locations were less reliable. In conclusion, the Gaofen-7 satellite had a great advantage in describing the spatial distribution of slope length and slope at the watershed scale, while being less capable of capturing slope length and slope at a specific site.

    • WANG Zilong, TENG Huaihao, JIANG Qiuxiang, LIU Chuanxing, SHAN Jiaxun, WANG Kai

      2024,38(2):147-156,164, DOI: 10.13870/j.cnki.stbcxb.2024.02.006

      Abstract:

      [Objective] In order to investigate the seasonal changes of base ions and available silicon and aluminum contents of black soil in northeast China under the change of snow depth in winter. [Methods] The environmental factors (temperature and humidity, moisture content, pH, total organic carbon), base ions, available silicon and activated aluminum of black soil in northeast China farmland were measured in snow removal group (SR), snow reduction group (SL), natural snow control group (C) and snow enhancement group (SA) were determined by artificial control of snow depth. The change process of the content of base ions and available silicon and aluminum in soil and their response to soil environmental factors were analyzed. [Results] The decrease of snow depth weakened the heat preservation effect of snow on black soil under seasonal snow cover, and the temperature and humidity (unfrozen water content) of 0—30 cm soil decreased significantly, which reduced the HCO3- content carried by unfrozen water during water and salt migration. The average pH of the soil was affected by the HCO3- content by the changes of -0.06, -0.04, - 0.02, and 0.01, respectively. With the decrease of soil alkalinity, the substitution ability of low-priced cations to high-priced cations in soil colloidal adsorption potential was enhanced, which increased the contents of exchange monvalent cations (Na+, K+), and decreased the contents of exchange and carbonate bivalent cations (Ca2+, Mg2+). Carbonate bivalent cation and exchange Na+ had positive and negative effects on TOC content, respectively, and the mean total organic carbon (TOC) content increased by 0.87, 1.09, 1.32 and 1.48 g/kg with the decrease of snow depth, respectively. The interaction between base ions and soil pH and TOC resulted in the decrease of soil pH and TOC content under the condition of reduced snow depth, which had an indirect effect on soil available silicon and aluminum content. The decrease of TOC content weakened the soil retention of low-active aluminum humate (Al-HA), and the decrease of pH promoted the conversion of low-active aluminum to high-active exchange aluminum (Ex-Al) and monomer hydroxyl aluminum (Hy-Al), which increased the soil aluminum toxicity, and promoted the dissolution of available silicon, resulting in the loss of soil silicon. [Conclusion] The reduction of seasonal snow cover in the middle and high latitudes caused by climate warming will affect the material and energy distribution of the black soil in Northeast China in winter, and thus change the growth and development environment of crops in the growing season. This study provided a certain scientific basis to reveal the seasonal variation process of soil mineral elements in the black soil region in Northeast China in winter.

    • ZHONG Zhiqiang, CAO Wenhua, MA Bo, ZENG Jianhui, ZHANG Xiumei

      2024,38(2):157-164, DOI: 10.13870/j.cnki.stbcxb.2024.02.003

      Abstract:

      [Objective] To investigate the effects of biological crustal cover and freeze-thaw on soil structure. [Methods] The effects of different freeze-thaw times, initial soil water content before freeze-thaw and biological crusting (algae crust) cover on soil structure characteristics was employed to analyze the indoor simulated freeze-thaw method. [Results] (1) The soil structure index (IGSS) obtained by orthogonal experiment was between 75.57~96.57, the signal-to-noise ratio (S/N) was between 37.55~39.70 dB, and the optimal factor combination ascertained by the Taguchi method was 15 freeze-thaw cycles, 15% initial water content, and 80% algal crust coverage, and the predicted results were IGSS=98.09, S/N=39.89 dB. (2)A positive correlation was observed between IGSSIGSS was positively correlated with freeze-thaw times, initial water content and algal crusting coverage, and the primary influences on the soil structure index were ranked as initial water content > freeze-thaw times > algal crusting coverage. The contribution rates of each factor to alterations in the soil structure index were initial water content (52.17%) > freeze-thaw frequency (31.95%) > algae crusting coverage (2.12%). (3) The change of soil structure index comes from the loss of soil water and pore expansion during the freeze-thaw process, and algae crusting can slow down the loss of water during the freeze-thaw process, thereby decelerating the IGSS alteration. [Conclusion] Orthogonal experiments in this research explored the effect of algae crusting cover on soil structure under freeze-thaw conditions, and the results could provide a theoretical reference for the study of soil freeze-thaw process under complex conditions.

    • LIAO Meiyu, FANG Xiuqin, JIANG Xinyuan, ZHU Qiuan, JIN Jiaxin, REN Liliang, YAN Yiqi

      2024,38(2):165-177,189, DOI: 10.13870/j.cnki.stbcxb.2024.02.030

      Abstract:

      [Objective] The study on the spatial-temporal change characteristics of land use/cover is of great significance for the protection and rational development of land resources in the Yellow River Basin, and can provide an important reference for the implementation of ecological protection and high-quality development strategy in the Yellow River Basin. [Methods] Based on the annual land use/cover data of the Yellow River Basin from 1980 to 2021, the characteristics of land use/cover change in the Yellow River Basin in recent 40 years were investigated by using Mann-Kendall and sliding t-test, geographic information TUPU standard deviation ellipse and gravity shift model. [Results] (1) From 1980 to 2021, forest land, shrub, water area, and construction land increased significantly, while the cultivated land, grassland, and wetland decreased significantly. (2) The periods of land use/cover change in the basin can be divided into 1980—1992, 1993—2001, 2002—2012, and 2013—2021, and the quantitative structure gradually presented by rapid changes, and the changes of construction land, wetland and water area were sensitive. The balance of land-use structure was gradually increased, and the stage changes showed a high correlation with the implementation of major strategic measures, and more consistent with the divided stage. (3) In the middle and upper reaches of the basin, the main changes were from 2012 to 2021 and intermittent changes, and the main changes were from 2001 to 2012 and from 2012 to 2021, and the main changes were from 2001 to 2012 and from 2012 to 2021, and the main changes were from arable land to construction land and grassland. The basin changed frequently in northern Ningxia, eastern inner Mongolia and some areas along the Yellow River system. (4) The centers of gravity of wetland, water and construction land moved westward, showing concentrated distribution to the southwest, east and northwest, respectively. [Conclusion] The overall trend of land use structure becomed better under the guidance of policies. In the future, we should pay more attention to wetlands and areas with frequent land use changes.

    • XU Nuojin, DING Bingbing, YU Xinxiao, JIA Guodong, FENG Yankai, LIN Jiawen

      2024,38(2):178-189, DOI: 10.13870/j.cnki.stbcxb.2024.02.026

      Abstract:

      [Objective] To quantitatively study the relationship between land use change and ecosystem service value in Sichuan section of the upper reaches of the Yellow River in the past 20 years, and to evaluate the effect of comprehensive ecological management in this section, so as to provided a basis for improving ethnic regional spatial planning, ecological environmental protection and management, and promoted the high-quality development of the Yellow River Basin. [Methods] Using the land use data of the upper reaches of the Yellow River in Sichuan in 2000, 2010 and 2020, land use change was analyzed based on land use dynamic attitude and land use matrix, and the economic value of the ecosystem service value equivalent per unit area of the terrestrial ecosystem in China was revised. The effects of land use change on the ecosystem service value in the upper reaches of the Yellow River from 2000 to 2020 in Sichuan were quantitatively studied. [Results] (1) From 2000 to 2020, the land use area of forest, desert, wetland and water system in the upper reaches of the Yellow River in Sichuan showed an increasing trend, while the land use area of cultivated land, shrub, grassland and glacial and snow in the upper reaches of the Yellow River showed a decreasing trend, and the land use change in 2010—2020 was more significant than that in 2000—2010. (2) The ecosystem service value of the upper reaches of the Yellow River in Sichuan in 2000, 2010 and 2020, was 1.27×1010, 2.51×1010, 3.92×1010 yuan, respectively, showing an increasing trend. The sensitivity analysis showed that the analysis results were reliable. Amongall land use types, grassland made the most significant contribution to total ecosystem value, and the contribution rate of grassland ecological service was 93.90% and 72.90% in 2000—2010 and 2010—2020, respectively, followed by wetland and forest land. (3) In the study area, the value of each individual ecosystem service showed an increasing trend in the past 20 years, and the sub-value of regional ecological service function was regulatory service>support service>supply service>cultural service. Among the 11 individual functions, the significant service value was climate regulation, hydrology regulation, soil conservation and biodiversity. The sum of the four items accounted for more than 69.50% of the total value. Land use change in the upper reaches of the Yellow River in Sichuan affected the changes of regional ecosystem service value, and grassland was the most significant, followed by wetland and forest land. [Conclusion] The results showed that the results of ecological governance in the past 20 years have been gradually enhanced, and the ecological environment has continuously improved.

    • BI Yinli, KE Zengming, GAO Xuejiang

      2024,38(2):190-196, DOI: 10.13870/j.cnki.stbcxb.2024.02.018

      Abstract:

      [Objective] To explore the water use characteristics of typical plants under different ecological measures at the waste dump, improve plant water use efficiency, and accelerate the ecological restoration process in mining areas. [Methods] Six ecological measures (control, inoculation, green fertilizer, inoculation+green fertilizer, inoculation+weathered coal, inoculation+green fertilizer+weathered coal) were implemented at the waste dump of the Heidaigou Coal Mine to treat Amorpha fruticosa. Stable isotopes of hydrogen and oxygen in water were combined with other techniques. [Results] (1) The soil moisture content of the waste dump was 3% to 9%, which was lower in the 0-30 cm and 70-100 cm soil layers, and higher in 30-70 cm soil layer. (2) Amorpha fruticosa obtained water from precipitation and soil. The soil water undergoes significant fractionation processed in the 0-30 cm soil layer, and exhibited significant differences among different ecological measures, with the green fertilizer treatment showing the highest and inoculation+green fertilizer treatment being the lowest. (3) Significant differences existed in the water use characteristics of Amorpha fruticosa under various ecological measures. The inoculation treatment exhibited a higher water use ratio of 53.4% in the 50-100 cm soil layer; The green fertilizer treatment mainly utilized the soil water in the surface layer (0-20 cm), which was 42.6%; The treatment of inoculation and green fertilizer had a relatively uniform proportion of soil water use in each layer. [Conclusion] The inoculation + green fertilizer treatment optimized the water use characteristics of Amorpha fruticose plants, increased the utilization ratio of surface and deep soil water, and can be used as an ecological reclamation measure for waste disposal sites, which promoted the ecological recovery rate and effect of arid mining areas in the western region.

    • HAN Xiaoyang, WANG Yaping, ZHU Yuanjun, LIU Wenzhao

      2024,38(2):197-204,215, DOI: 10.13870/j.cnki.stbcxb.2024.02.029

      Abstract:

      [Objective] To investigate the spatial distribution and cooperative utilization characteristics of soil water under the orchard-farmland mosaic pattern in the southern Loess Tableland. [Methods] The 10-year-old, 21-year-old, and 25-year-old apple orchards (AO10, AO21, and AO25) and their adjacent farmland were selected in Changwu tableland were selected to quantitatively calculate the contribution of soil water storage to water consumption of orchard. By measuring the soil water content at relevant sites in the orchard-farmland interface zone after the rainy season in 2021. [Results] The precipitation in 2021 is 756 mm, which was a typical wet year. The rainfall infiltration depth of farmland and AO21, AO25 orchards reached 8.4, 7.0, and 5.0 m at the end of November, respectively. AO10 orchard-farmland boundary zone is 4 m deep, the soil water content in the lower part is larger than that in the upper part, and the average soil water content was 25.5% in the 4—10 m soil layer. In AO21 orchard, the average soil water content of the 0—7 m soil layer was 22.1%, and that of the 7—10 m soil layer was 15.0%. the average soil water content of the 0—5 m soil layer of AO25 orchard was 20.9%, and that of 5—10 m was 13.6%. The soil dry layer of AO21 and AO25 orchard was below 7.0 and 5.0 m, respectively. In the horizontal direction, the distance of soil water used by AO21 and AO25 orchards from adjacent farmland reached 5 and 8 m, respectively, and the water supply from fields to orchards at the agro-fruit interface was 0.08 and 0.25 m3/m2 when the soil profile was divided by the upper boundary of the dry layer. Below is the actual water supply, which is 0.45 and 0.81 m3/m2, respectively. [Conclusion] The mosaic layout of apple orchards and farmland in the Loess tableland region is a reasonable utilization structure, and factors such as the age of apple trees and the width of adjacent farmland should be considered in land planning and management. The research results will contribute to promote the sustainable utilization and spatial optimization of regional soil water resources.

    • ZHI Fei, ZHOU Zhenhong, ZHAO Ming, WANG Shiqi

      2024,38(2):205-215, DOI: 10.13870/j.cnki.stbcxb.2024.02.033

      Abstract:

      [Objective] To seek a new urban development plan of Hefei under the guidance of "double carbon" goal. [Methods] Based on the land use data of Hefei City in the 5th period from 2000 to 2020, under the guidance of territorial spatial Planning of Hefei City, the spatio-temporal evolution law of land use in 2035 was simulated by the PLUS model, and the spatio-temporal change characteristics of carbon storage in Hefei City under multiple scenarios were explored by coupling the InVEST model. And further explore the effect of the comprehensive land use on the carbon storage. [Results] (1) The main characteristics of land use change in Hefei City from 2000 to 2020 were the decrease of cultivated land and forest land, among which cultivated land was the main source of construction land expansion. The law of land change in the natural development and farmland resource protection scenarios was roughly the same, mainly represented by the reduction of cultivated land, forest land and water body. In the green urban development scenario, the area of forest land changed from decreasing to increasing compared with the other two scenarios. (2) Carbon storage in Hefei City decreased year by year from 2000 to 2020, and the carbon loss was the most 2005 to 2010. By 2035, the carbon reserves of natural development scenario, farmland resource protection scenario and green urban development scenario were 138.96×106 t, 140.13×106 t, and 139.81×106 t, respectively. Under the farmland resource protection scenario, the area with the lowest increase of carbon storage significantly slowed down the expansion of the construction land. under the scenario of urban development, forest land changes from carbon loss to carbon sequestration, which was the most potential trend of carbon sequestration. (3) The land utilization rate of green urban development scenario was the highest, which can effectively reduce the threat of comprehensive land use degree to carbon storage loss. [Conclusion] Both farmland resource protection scenario and green accumulation urban development scenario were conducive to urban carbon sequestration development. Implementing parallel policies of ecological protection and urban development, and adjusting comprehensive land use mode were conducive to improving urban carbon loss.

    • YU Wenguang, CHEN Yunzhi, TANG Lifang, WANG Xiaoqin

      2024,38(2):216-233,245, DOI: 10.13870/j.cnki.stbcxb.2024.02.034

      Abstract:

      [Objective] Simulating the change of runoff and sediment changes in the watershed under the influence of land use and climate in the future is conducive to making suitable management plans. [Methods] Based on land use and meteorological data, combined with CMIP6 climate model data, PLUS model and SWAT model, the temporal and spatial changes of land use and runoff and sediment under different climate scenarios in 2030 were quantitatively simulated. [Results] (1) The SWAT model exhibited good accuracy in monthly scale in simulation of Minjiang River Basin, in which the R2 and NSE (Nash-Sutcliffe Efficiency) ranged from 0.80 to 0.95 and 0.75 to 0.91, respectively. The R2 and NSE ranged from 0.75 to 0.98 and 0.64 to 0.94 respectively. (2) Using the land use data of 2020 to evaluate the accuracy of the PLUS model, the Kappa coefficient was 0.77, and the simulated construction land and cultivated land in the Minjiang River Basin in 2030 would increase by 325.64 km2 and 1 157.51 km2, respectively. (3) Under the SSP2-4.5 and SSP5-8.5 scenarios, the average precipitation in 2025—2035 would increase by 0.15% and 2.18%, and the average annual temperature would increase by 0.23 and 0.62 ℃, respectively. (4) In the low carbon and high carbon scenarios, only land use change led to an increase of 0.08% and 0.07% in annual mean runoff, and an increase of 0.24% and decreased of 0.05% in annual mean sediment transport, respectively, compared with the baseline period. Compared with the baseline period, the mean annual runoff decreased by 4.76% and 4.11%, and the mean annual sediment transport increased by 18.12% and 0.13%, respectively. The combined effects of land use and climate resulted in a decrease of 4.57% and 3.93% in annual average runoff and an increase of 18.28% and 0.33% in annual average sediment transport compared with the base period, respectively. (5) Under the scenario of future climate and land use comprehensive change, the areas with higher and larger increase in surface runoff and sediment yield were concentrated in the northwestern of the basin centered on Shaowu City in Nanping and the southwest of the basin centered on Jiangle County in Sanming. [Conclusion] These research results provide some reference for the reasonable development and construction of Minjiang River basin in the future.

    • TAN Hao, TUO Yunfei, FENG Yongyu, HE Lisha, CHANG Xiang, LU Qiwei, HE Xiahong

      2024,38(2):234-245, DOI: 10.13870/j.cnki.stbcxb.2024.02.016

      Abstract:

      [Objective] To reveal the vertical distribution differences of soil nitrogen components (total nitrogen, hydrolyzed nitrogen, ammonium nitrogen, nitrate nitrogen) in Liziping National Nature Reserve in Sichuan Province and their relationships with physicochemical factors. [Methods] In March, June, September and December 2022, the vertical variation characteristics of soil nitrogen components and physicochemical factors at altitudes of 1 800 m, 2 100 m, 2 400 m and 2 700 m in Liziping, Sichuan Province were determined and analyzed, and the relationship between environmental factors and nitrogen components and their seasonal differences were analyzed by multivariate analysis of variance and redundancy analysis. [Results] (1) Altitude, season and their interaction had significant effects on soil nitrogen composition, and in March, June, September and December the ammonium nitrogen content was 2 100 m>2 400 m>1 800 m>2 700 m above sea level, and the nitrate nitrogen content was 2 400 m>2 100 m>2 700 m>1 800 m above sea level, and the gradient increased over the month, the contents of total nitrogen and nitrate nitrogen showed a trend of increasing first, with the maximum content of total nitrogen and nitrate nitrogen being 1.25 g/kg and 8.26 mg/kg, respectively, in December, and the maximum content of hydrolyzed nitrogen and ammonium nitrogen in March being 185.14 mg/kg and 5.80 mg/kg respectively. The variation of total nitrogen, hydrolyzed nitrogen, ammonium nitrogen and nitrate nitrogen along the soil layer was consistent, and formed a "V" shape. (2) The vertical variation characteristics between physicochemical factors and nitrogen components in different seasons and altitudes were significantly different, and the contents of total phosphorus, available phosphorus and available potassium increased first and then decreased along the depth of soil layer. (3) Seasonal differences in the key factors affecting soil nitrogen composition, organic matter, non-capillary porosity, available potassium, total phosphorus, available phosphorus and capillary porosity in March and December, and organic matter, total potassium and capillary porosity, total phosphorus and available potassium in June and September. [Conclusion] This study provides a specific production practice basis for the response mechanism of soil nutrients to altitude and season and the comprehensive management of ecological conservation in nature reserve.

    • HUANG Tao, LIU Suhong

      2024,38(2):246-257, DOI: 10.13870/j.cnki.stbcxb.2024.02.013

      Abstract:

      [Objective] The forest coverage rate of Fujian Province is as high as 66.8%, ranking first in China. To investigate the impact of land use changes on carbon storage in Fujian Province is the theoretical basis for exploring the balance between social development and ecological protection. [Methods] Based on the carbon storage module of PLUS model and InVEST model, relationship between the spatiotemporal change characteristics of carbon storage and land use types in Fujian province during 2000—2020 was revealed, and the spatial and temporal changes of carbon storage in Fujian Province during 2020—2030 were predicted from three scenarios: natural development, ecological protection and urban development. [Results] The total carbon reserves in the study area in 2000, 2010 and 2020 were 214.77×107, 214.51×107 and 212.93×107 t, respectively, indicating a downward trend year by years. The development and transformation of land by human activities was the dominant factor leading to changes in carbon stocks, and the conversion of large areas of cultivated land and forest land into urban areas was the primary reason for the decline in carbon stocks. The prediction results showed that compared with 2020, carbon storage under natural development, ecological protection and urban development in 2030 would decrease by 1.47×107 t, increase by 0.17×107 t, and decrease by 1.85×107 t, respectively. The ecological protection scenario was the only development scenario that reversed the decline in carbon stocks. Compared with 2020, the forest area had expanded by 1 900.87 km2 and the forest carbon storage had increased by 2.08×107 t, which could effectively protect the ecology and meet the land requirements for urban development. [Conclusion] Prioritizing forest land protection and controlling the expansion of construction land are crucial prerequisites for Fujian Province to achieve carbon peaking and carbon neutrality goals.

    • LIU Jiayi, XU Dawei, XU Jia

      2024,38(2):258-267, DOI: 10.13870/j.cnki.stbcxb.2024.02.024

      Abstract:

      [Objective] Through the spatio-temporal dynamic analysis of landscape ecological pattern and habitat quality, the response of habitat quality before and after the implementation of soil and water conservation measures in PU River Basin of Shenyang City was deeply studied, aiming to provide scientific basis for soil and water conservation strategies in small river basins, so as to promote the coordinated growth of the eco-economy and the sustainable and healthy development of regional ecology. [Methods] Based on the land use data and Digital Elevation Model (DEM) of PU River Basin in 2000, 2010 and 2020, combined with the FRAGSTATS and InVEST models, land use transfer matrix, landscape pattern index, habitat quality and habitat degradation degree were used to analyze land use change and explore quality response situation. [Results] (1) During the period from 2000 to 2010, the cultivated land development activities in the PU River Basin were frequent, resulting in a significant decline in the proportion of forest, grassland and other land types; In the period from 2010 to 2020, the construction of the PU River ecological corridor will promote the change of land use, and the cultivated land area will flow to artificial surfaces, forests and grasslands. (2) During 2000 to 2020, the overall landscape pattern of the PU River Basin experienced a process of first becoming complete and then fragmentary. The landscape on both sides of the Puhe River formed a dense pattern of multiple elements, and the habitat in the northern edge of the urban center continued to fragment. (3) From the overall analysis of the basin, the average habitat quality in 2000, 2010, and 2020 was 0.349, 0.329, and 0.354, respectively, showing a trend of first decreasing and then increasing. The mean values of habitat degradation were 0.098, 0.112, and 0.086, which were consistent with the trend in habitat quality. With the construction of the PU River Ecological Corridor, the quality of habitat will be improved significantly in 2020, and the threats to the ecosystem will be reduced. From the analysis of spatial pattern, the northeast and southwest show obvious spatial distribution characteristics. The quality of habitat in the mountainous areas of northeast China and the wetlands of southwest China is generally good, but there is a threat of habitat degradation. [Conclusion] Under the influence of soil and water conservation measures, the ecological pattern of the PU River Basin can be and the degradation of habitat can be effectively inhibited.

    • ZHANG Longjiang, ZHAO Junsan, CHEN Guoping, LIN Yilin, LIU Fengru, PENG Sufen

      2024,38(2):268-277, DOI: 10.13870/j.cnki.stbcxb.2024.02.032

      Abstract:

      [Objective] Sustainable Development Goal 15.3.1 (SDG 15.3.1) is one of the important indicators to characterize land degradation.Exploring the impact of land use change and ecosystem service values (ESVs) on SDG 15.3.1 is a key factor to improve land degradation. [Methods] Based on land use and carbon stock changes, a new evaluation rule was established for SDG15.3.1 index, and the completion of SDG 15.3.1 was evaluated. The equivalent factor method was used to calculate the value of ecosystem services to quantitatively analyse the impact of land use change on ESV. [Results] (1) The land use type change was frequent in the study area, which mainly showed that high forest land, water body and construction land increased, cultivated land, grassland and shrub decreased, and unused land remained basically unchanged; (2) The spatial distribution pattern of ESV was high in the middle, low arround, high in the west and low in the east; From 2000 to 2020, the total ESV loss was 7.32×108 yuan. From 2000 to 2010, the ESV loss of land degradation area was 3.03×109 yuan. From 2010 to 2020, the ESV loss in land degradation areas was 2.28×109 yuan. (3) According to the evaluation results of SDG15.3.1, the indicators of SDG15.3.1 for 2000—2010 and 2010—2020 are 5.22 percent and 4.77 percent, respectively, while the net land restoration area was -1.62×105 hm2 and -2.4×105 hm2. The SDG15.3.1 target had improved, but the zero land degradation growed target is still not achieved. [Conclusion] The research results provided a reference for the impact of land use change on ecosystem services in the process of achieving SDG 15.3.1 in plateau urban agglomerations.

    • YIN Li, WEI Wei, BO Liming, ZHANG Ke, XIA Junnan

      2024,38(2):278-293, DOI: 10.13870/j.cnki.stbcxb.2024.02.025

      Abstract:

      [Objective] To scientifically understand the spatio-temporal evolution process and formation mechanism of urban space, agricultural space and ecological space in Qinling-Daba Mountain area is the key to promote the overall coordination of the national spatial development pattern and the rise of the central and western regions, and it is also an urgent need for high-quality transformation and development of the region. [Methods] Based on the methods of spatial transfer matrix, topographic location analysis and random forest regression, the spatial and temporal evolution characteristics and driving mechanism of Qinba Mountain region during 2000—2020 were studied from two dimensions of "pattern scale-topographic location". [Results] (1) In the past 20 years, the cities and towns in the Qinba Mountain area expanded dramatically, and the agricultural and ecological space continued to shrink. While the population of 58.33% of the counties decreased, the urban land was still expanding, and the "total population and urban size" showed a serious polarization. (2) The phenomenon was characterized by urban and agricultural space "climbing up the hills", while ecological space "descended into the valleys". The newly added urban and agricultural space was moved up 1 to 2 topographic positions on average. The dam elevation project of Danjiangkou Reservoir downstream had a significant impact on the overall spatial distribution gradient of the mountainous areas. (3) The dynamic adjustment and replacement of "agricultural space to ecological space" was the leading type of transformation in Qinba Mountain area, and the influence of fiscal expenditure was the most significant. Agricultural space was the main source of new towns, and the scale of urban degradation into agricultural and ecological space was significant in Qinba mountain area. (4) Land development policies, mountain terrain attributes, traffic location conditions and social and economic factors jointly restrict and affect the results of territorial spatial evolution in Qinba Mountain area, and there were obvious differences in the effect intensity and the number of significant factors of various types of factors in different conversion directions. [Conclusion] Promoting the concentration of new towns to the key development zones, scientifically guiding agricultural and ecological space to conform to the topographic gradient layout, carefully carrying out water conservancy project construction, and planning the overall regional layout of the "Three districs and Three lines" will have a positive impact on the optimization of territorial spatial pattern in Qinba Mountain area.

    • SONG Xiaomei, CHANG Xiaoli, DING Chen

      2024,38(2):294-303, DOI: 10.13870/j.cnki.stbcxb.2024.02.035

      Abstract:

      [Objective] In order to understand the spatiotemporal changes in the wetland of the Genhe Basin, the impacts of climate change and land use change on wetland landscape pattern was clarified. [Methods] The driving factors of changes in wetland landscape pattern in the Genhe Basin between 1990 and 2019 were investigated by analyzing the changes in wetland extent and combining them with climate change during the same period. [Results] The results showed that over the past 30 years, the area of wetlands in the Genhe Basin had decreased by 31.89%, the number of patches had increased by 3.74%, and the landscape fragmentation index had increased by 4.48. The overall degradation of wetland areas in the watershed was significant, while the overall number of wetland patches in the watershed had increased. From 1990 to 2004, wetland areas in the watershed showed a significant degradation trend (p<0.05). There was a significant positive correlation between wetland areas and annual precipitation, while there was a significant negative correlation between landscape fragmentation index and annual precipitation. It was inferred that annual precipitation was the main factor causing significant changes in wetland landscape patterns in the Genhe Basin. From 2004 to 2019, the degradation trend of wetlands in the watershed was not significant (p>0.05), and the average annual temperature showed a non-significant increasing trend (p>0.05). There was a significant negative correlation between landscape fragmentation index and average annual temperature, which might be due to the melting of shallow permafrost in the watershed due to rising temperatures, leading to a decrease in wetland fragmentation during this period. [Conclusion] The research results are of great significance for maintaining biodiversity and stability of wetland ecosystems in the Genhe Basin, promoting coordinated and interactive wetland-dryland relationships, and ensuring sustainable development of wetland resources.

    • LI Zhuyu, LI Zhicheng, XU Guiqian, DUAN Xu, ZHANG Guanghe, ZHAO Yangyi

      2024,38(2):304-315, DOI: 10.13870/j.cnki.stbcxb.2024.02.012

      Abstract:

      [Objective] To investigate the impact of soil aggregate structure on the formation of preferential pathways in the gully system of the dry-hot valley of the Jinsha River to enhance our understanding of soil moisture and solute transport in the gully system. [Methods] We selected different sections (i.e., catchment area, gully head, gully bed, and gully bottom) of both active and stable gullies in the dry-hot valley of the Jinsha River as our research subjects. We used staining tracers and morphometric image analysis techniques to extract the preferential pathways from the soil level profile. RDA (Redundancy Analysis), gray correlation, and coupled coordination were used to explore the relationship between soil aggregate structure and preferential pathways. [Results] (1) The stability of soil aggregates in stable gullies were higher than those in active gullies. Except for specific soil layers, the contents of mechanically stable aggregates (>0.25 mm, [QX(Y12#]DR[QX)]0.25), water-stable aggregates (>0.25 mm, [QX(Y12#]WR[QX)]0.25) and average mass diameter (MWD) in active gully were significantly lower than those in the stable gully ([QX(Y12#]p[QX)]<0.05). The aggregate destruction rate (PAD) and unstable aggregate index ([QX(Y12#]E[QX)]LT) showed the opposite trend. As the gully system extends from the catchment towards the gully bottom, the fraction of large soil and the stability of aggregates all decreased. (2) The number and connectivity of preferential pathways in active gullies were higher than those in stable gullies. However, the connectivity of the preferential pathways in the gully system deteriorated as it extended from the catchment to the bottom of the gully. The preferential pathways with a diameter>10 mm served as primary channel. The Simpson index of active gullies exhibited an increase by 3.12% compared to stable gullies, indicating a higher richness of preferential pathways across different diameter classes. (3) The formation and distribution of preferential pathways were affected by the stability of soil aggregates, and MWD and WR0.25 were strongly correlated with the number of preferential pathways and had the most significant influence ([QX(Y12#]p[QX)]<0.01). (4) As the gully system extended from the catchment to the bottom of the gully, the coupling coordination between the soil aggregate structure and the preferential pathways decreased. Overall, the order of performance was as follows: gully head>catchment area>gully bottom>gully bed. [Conclusion] Soil aggregate structure is an of the important driving factors for the formation of preferential paths, and the distribution of preferential paths has significant impact on the development of gully systems in dry-hot valleys.

    • LU Zhaoyang, MA Weiwei, DU Jianan, CHANG Wenhua, HE Wanpeng, LI Shuzhuo

      2024,38(2):316-325, DOI: 10.13870/j.cnki.stbcxb.2024.02.020

      Abstract:

      [Objective] To examine the response characteristics of soil carbon and nitrogen fractions in alpine wetland soil to climate warming and nitrogen deposition. [Methods] Using open-top box warming (OTC) and adding exogenous nitrogen (NH4NO3) to simulate future climate warming and nitrogen deposition tests, four treatments were established, namely control (CK), warming (W), nitrogen application (N), and warming nitrogen (WN). The soil carbon and nitrogen levels were quantified after 1.5 years. [Results] (1) The utilization of the open top box warming device resulted in a notable elevation of the mean temperature at 0—20 cm soil layer by 1.126 ℃. Additionally, this intervention led to a significant decrease in the water content (SMC) and pH levels, as well as the concentrations of soil total nitrogen (TN), microbial nitrogen (MBN), ammonium nitrogen (NH4+—N), organic carbon (SOC), and dissolved organic carbon (DOC) at the 0—10 cm soil layer. Conversely, there was an observed increase in the concentration of nitrate nitrogen (NO3-—N). (2) Nitrogen application considerably lowered the contents of NH4+—N and SOC in all the soil layers, as well as those of the contents of microbial biomass carbon (MBC) and DOC in soil layers 10—20 cm deep, but increased the contents of TN, MBN, and NO3-—N. (3) The application of nitrogen through warming conditions resulted in a large rise in SMC, TN, NO3-—N, and MBC content. Conversely, it led to a significant reduction in MBN, NH4+—N, and DOC. (4) Correlation analysis showed that there was a positive correlation between soil moisture and all physicochemical factors, and soil carbon and nitrogen components were positively correlated. [Conclusion] The results indicated that the simulated warming application of nitrogen alleviated the temperature and nitrogen limitation of plant growth in the Gahai wetland, promoted the accumulation of TN, and had a greater impact on the soil microbiota biomass carbon and nitrogen , which led to the conversion of soil microbial biomass carbon and nitrogen activities and distribution characteristics.

    • LU Lianxin, WANG Keqin, LI Zhuyu, ZHAO Yangyi, WANG Shuaibing

      2024,38(2):326-338, DOI: 10.13870/j.cnki.stbcxb.2024.02.027

      Abstract:

      [Objective] To study the effect of contour reverse-slope terrace (CRT) on micro-ecological characteristics of rhizosphere soil in maize continuous cropping and maize-kidney bean rotation system. [Methods] With corn bean wheel as the study object and corn bean joint as the control, the crop root exudates and soil microbial community composition and structural characteristics of were analysed by GC-MS and high-throughput sequencing technology by combining field in-situ monitoring and sampling with laboratory analysis. To study the effects of CRT on the species and content of root exudates and the composition and diversity of soil microbial community in maize continuous cropping and maize-kidney bean rotation. [Results] (1) The relative content change of root exudates was more prominent in CRT measures and more significant in crop rotation mode. (2) CRT2 treatment had a more significant effect on improving the quantity, richness and diversity of soil microbial community. (3) Under the interaction between root exudates and soil microorganisms, the pair-based correlation between root exudates, soil microorganisms, and soil environmental factors was more significant under CRT2 treatment. [Conclusion] CRT changed the root soil microecological environment of crops by changing the root secretion content of maize continuous cropping and maize-kidney bean rotation, and improved the number, diversity and richness of soil microorganisms. Moreover, the combination of this measure and corn-kidney bean rotation can improve the micro-ecology of root soil more significantly. The research results provide theoretical basis for crop planting, cultivation method selection, soil microenvironment improvement and soil erosion control.

    • ZHU Zhengqing, MAN Xiuling

      2024,38(2):339-350,363, DOI: 10.13870/j.cnki.stbcxb.2024.02.031

      Abstract:

      [Objective] Due to the large differences in understorey vegetation and soil physicochemical properties of Larix gmelinii forest in the cold temperate zone of the Rreater Khingan Mountains, the characteristics and availability of soil phosphorus morphological changes of Larix gmelinii forest under different forests were studied, so as to provide scientific data for scientific evaluation of soil phosphorus supply level and phosphorus cycle in the cold temperate zone forest. [Methods] Four kinds of understory vegetation in the cold temperate zone of the Greater Khingan Mountains, namely, Larix gmelinii forest (Rhododendron simsii-Larix gmelinii forest, Rhododendron tomentosum-Larix gmelinii forest, Carex schmidtii-Larix gmelinii forest and Moss-Larix gmelinii forest) were selected as the research objects. Soil samples from the 0—5 cm, 5—10 cm and 10—20 cm soil layer were collected from June, August and October 2022. Hedley phosphorus classification method was used to determine the phosphorus content of different forms in soil. [Results] (1) During the observation period, soil active phosphorus (H2O—Pi, NaHCO3—Pi, NaHCO3—Po) and medium active phosphorus (NaOH—Pi, NaOH—Po) of the four understorey vegetation Larix gmelinii forest showed a decrease trend from June to October, and the content of medium active phosphorus accounted for 30.08% to 52.80% of total phosphorus.The content of inorganic phosphorus was higher than that of organic phosphorus. The content of active phosphorus and medium active phosphorus in 0—20 cm soil layer of Rhododendron simsii-Larix gmelinii forest and Rhododendron tomentosum-Larix gmelinii forest were higher than those of the Carex schmidtii-Larix gmelinii forest and Moss-Larix gmelinii forest. The soil stability phosphorus (HCl—Pi, HCl—Po, and residual—P) in the Carex schmidtii-Larix gmelinii forest was significantly higher than that in the other three larix forests, and the stable state phosphorus accounted for 58.86%~65.81% of the total phosphorus. (2) Soil total phosphorus (TP), available phosphorus (AP) and phosphorus activation coefficient (PAC) in Larix gmelinii forest were 391.81 to 1 081.02, 7.34 to 83.90 mg/kg, and 1.62% to 7.76% from June to October, respectively. The content of AP and PAC in the soil of the Rhododendron simsii-Larix gmelinii forest and Rhododendron tomentosum-Larix gmelinii forest were higher than those of the other two larix forests, showing higher phosphorus availability. On the other hand, there was insufficient phosphorus supply in the soil layer of the Carex schmidtii -Larix gmelinii forest and Moss-Larix gmelinii forest from 5—10 cm and 10—20 cm in August and October. (3) Soil moisture contentwas the main influencing factor of soil phosphorus in the Rhododendron simsii-Larix gmelinii forest and the Rhododendron tomentosum-Larix gmelinii forest, soluble carbon was the main influencing factor of the Carex schmidtii-Larix gmelinii forest, and ammonium nitrogen had a greater influence on the Moss-Larix gmelinii forest. [Conclusion] Understory vegetation had a significant effect on soil phosphorus morphological form and phosphorus availability in Larix gmelinii forest. The content of active phosphorus, medium active phosphorus and available phosphorus in the soil of Rhododendron simsii-Larix gmelinii forest and Rhododendron tomentosum-Larix gmelinii forest was higher, and the activation coefficients of P were all above 2.00%; However, the content of stable phosphorus in soil of the Carex schmidtii-Larix gmelinii forest was higher, and the availability of soil phosphorus was lower. This results are of great significance for the study of ecological function of understory vegetation and soil nutrient cycle in the cold temperate forest ecosystem.

    • YANG Hualei, WANG Xiaoqing, ZHANG Meiwei, GUO Qian, WANG Huili, ZENG Lingtao, CUI Yupei, SUN Xiaolin

      2024,38(2):351-363, DOI: 10.13870/j.cnki.stbcxb.2024.02.037

      Abstract:

      [Objective] In order to investigate the influencing factors and variation rules of accuracy of various two-step models of 3D mapping methods. [Methods] Soil organic carbon in a forest with an area of about 5 km2 in a typical hilly region of South China was mapped. Spline functions, exponential functions and power functions were used as depth functions, ordinary kriging and random forest were used as horizontal mapping methods and two different mapping forms (called forms A and B) were used. The 3D prediction mapping of soil organic carbon was carried out, and the influence of different depth functions, horizontal mapping methods and mapping forms on the 3D mapping results of two-step model was explored. [Results] (1) The depth function largely determined the variation of mapping results in vertical and horizontal directions, which showed that the variation of the mapping results was significantly different among the three depth functions. Exponential function had the largest variation and power function had the weakest variation, while horizontal mapping methods (ie.ordinary kriging and random forest) had little influence on the vertical variation of mapping results. However, the spatial variation of surface layer was greatly affected by the horizontal mapping methods. (2) The accuracy of spline function was the best because the simulated depth curve was in the best agreement with the measured values. The consistency correlation coefficients (CCC) of the 3D mapping based on the spline function were 0.72 and 0.75, which were higher than the other functions in the same form of 3D mapping (CCC were between 0.64 and 0.74). For the horizontal mapping methods, the accuracy of the ordinary kriging was better than that of the random forest, the CCC of the former was between 0.67 and 0.75, the latter was between 0.64 and 0.72; (3) The two mapping forms of the two-step model had little influence on accuracy. Only in the case of prediction for bottom layer, form A (i.e., horizontally mapping simulated walues of a depth function was better than form B (i.e., simulating parameters of a depth function).(4) Among all 3D mapping methods, the form A, with ordinary kriging and spline functions, had the highest accuracy, generating coefficient of determination (R2) of 0.76, CCC of 0.75, and root mean square error (RMSE) of 3.50 g/kg. [Conclusion] In the two-step model of 3D soil mapping, firstly, the spline function should be considered as the depth function. Secondly, the horizontal mapping method should be considered according to the landscape conditions and sample size. Finally, the first mapping form of the two-step model should be adopted as far as possible.

    • LU Rui, ZHANG Mingjun, ZHANG Yu, CHE Cunwei, QIANG Yuquan, LIU Lingling, WANG Zhilan, GU Lailei

      2024,38(2):364-376, DOI: 10.13870/j.cnki.stbcxb.2024.02.039

      Abstract:

      [Objective] Precipitation is the main source of soil water in arid and semi-arid regions. By combining field observation and model simulation to study the regularity of rainfall infiltration, the soil water deficit can be mastered more systematically. [Methods] Through fixed point observation, the Hydrus-1d model was applied to simulate the dynamic change of soil water in Platycladus orientalis on the artificial of Nanshan Mountain in Lanzhou, evaluate the applicability of the model in arid region, and analyze the soil water response and infiltration mechanism under different rainfall conditions. [Results] The Hydrus-1d model had good applicability in the artificial side of Nanshan in Lanzhou, and the deep simulation effect was better. When the rainfall was less than 30 mm, the soil moisture content at 10 cm has the strongest response to rainfall, while the influence of rainfall at 30 and 50 cm was relatively small and had an obvious lag, and there was no response below 70 cm. There was a wetness peak when the rainfall was more than 8.2 mm. During the simulation period, the maximum infiltration depth was 70 cm and the maximum infiltration volume was 23.7 mm. The infiltration depth increased with time, while the infiltration volume and infiltration rate decreased with time. Rainfall was positively correlated with infiltration volume, infiltration depth and infiltration rate (p<0.05). When the rainfall was less than 20 mm, the rainfall intensity had a significant effect on the infiltration amount, infiltration depth and infiltration rate. [Conclusion] The Hydrus-1d model can be used to simulate the dynamic change of soil water in Platycladus orientalis on the artificial of Nanshan in Lanzhou and calculate the infiltration amount, infiltration rate and infiltration depth. Moreover, it is found that the rainfall has a more significant effect on the soil water infiltration process.

    • HE Lingyun, CHEN Fusheng, ZHENG Zhiyu, LIU Qiao, WANG Shengnan, WANG Fangchao

      2024,38(2):377-386, DOI: 10.13870/j.cnki.stbcxb.2024.02.023

      Abstract:

      [Objective] To explore how phosphorus input regulates the effects of atmospheric nitrogen deposition on soil aggregate organic carbon content and the relationship between carbon and phosphorus. [Methods] A long-term monitoring test platform for nutrient addition was established in evergreen broad-leaved forest soil for 6 years (2015—2021), including 4 treatments: Control [P0+N0, P 0 kg/(hm2·a)+N 0 kg/(hm2·a)], nitrogen addition [P0+N100, P 0 kg/(hm2·a)+N 100 kg/(hm2·a)], phosphorus input [P50+N0, P 50 kg/(hm2·a)+N 0 kg/(hm2·a)] and nitrogen and phosphorus were simultaneously input (P50+N100, P 50 kg/(hm2·a)+N 100 kg/(hm2·a)\], and each treatment was repeated 3 times, and a total of 12 plots were obtained. 0—10 cm soil samples were collected from the sample site in August 2021 to determine the basic physical and chemical properties, soil particle size distribution, phosphorus components of soil aggregates of different particle sizes, and organic carbon (SOC) content. [Results] (1) Under P0 treatment, nitrogen addition significantly increased the proportion of large aggregates, decreased the clay and powder contents, and increased the SOC content in each aggregate particle size. Nitrogen addition significantly decreased and increased the content of labile phosphorus (LP) and residual phosphorus (RP) in aggregate clay and powder, respectively. (2) Under P50 treatment, nitrogen addition significantly increased the geometric mean diameter (GMD) of soil aggregates, but had no significant effects on phosphorus components and SOC contents in aggregates of different particle sizes. (3) Under P0 treatment, soil aggregate SOC was positively correlated with refractory phosphorus. There was no significant correlation between SOC of soil aggregates and functional phosphorus components under P50 treatment. It was concluded that under P0 treatment, nitrogen addition could increase soil organic carbon retention by increasing the refractory phosphorus in soil aggregate clay and powder particle size of evergreen broad-leaved forest. Under P50 treatment, the effect of nitrogen addition on organic carbon in each particle size may be regulated by biological factors and has nothing to do with the availability of phosphorus. [Conclusion] The effect of nitrogen deposition on the internal relationship of carbon and phosphorus in soil aggregates in evergreen broad-leaved forests was regulated by phosphorus. The results of this study provide data supported for forest soil carbon cycling in response to global climate change.

    • LI Chuanfu, XU Jialin, MING Yufei, GAO Shu, LÜ Xin, YANG Yuxuan, LI Yongqiang, JIAO Shuying

      2024,38(2):387-397, DOI: 10.13870/j.cnki.stbcxb.2024.02.021

      Abstract:

      [Objective] In order to investigate the effects of mushroom residue organic fertilizer and desulfurized gypsum on organic carbon components and carbon pool management index (CPMI) of saline-alkali soil. [Methods] The newly reclaimed wheat-maize rotation land in the Yellow River Delta was used as the research subject, and the randomized block experiment method was conducted to set up four treatments: no fertilization (CK), conventional farming fertilization (CN), mushroom residue organic fertilizer (MCOF), mushroom residue organic fertilizer and desulfurized gypsum (MCOG), which were treated by field fertilization for 3 years. [Results] The combined application of mushroom residue organic fertilizer and desulfurized gypsum significantly reduced the salinity of 0—20 cm soil layer, and increased the soil nitrogen, phosphorus and potassium nutrition content and cation exchange capacity (p<0.05). The contents of total organic carbon (TOC), easily oxidized organic carbon (EOC) and microbial biomass carbon (MBC) in 0—20 cm soil layer were higher than those in 20—40 cm soil layer, while the water-soluble organic carbon (WSOC) was lower than that in 20—40 cm soil layer. In the 0—20 cm soil layer, compared with the CN treatment, the MCOG treatment significantly increased soil TOC, EOC, WSOC, and MBC by 15.48%, 23.50%, 18.98%, and 51.40%, respectively. The effective rates of EOC and MBC increased by 13.94% and 30.49%, respectively. There was no significant effect on the effective rate of WSOC. The combined applicationof organic fertilizer and desulfurized gypsum significantly increased the soil CPMI, which increased by 15.38% and 20.00% compared with the CN and the CK treatments, respectively. The sensitivity index of MBC was higher than that of other organic carbon components, and the MBC value of MCOG treatment was the highest. Correlation analysis showed that soil TOC content depended on its active components, while the main factors affecting the content and effective efficiency of organic carbon active components, as well as the CPMI, are pH, CEC, and EC. [Conclusion] Therefore, the combined application of mushroom residue organic fertilizer and desulfurized gypsum can significantly decrease soil alkalinity, improve soil fertility and enhance carbon sequestration efficiency of saline-alkali soil. This research provides a theoretical basis and data support for expanding organic improvement methods in saline-alkali soil of the Yellow River Delta.

    • RUAN Guojie, HU Qi, SHI Qian, GAO Xiaodong, LI Changjian

      2024,38(2):398-405, DOI: 10.13870/j.cnki.stbcxb.2024.02.009

      Abstract:

      [Objective] The aim of this study is to investigate the effects of different residue amounts on nitrogen utilization efficiency and losses. [Methods] The experiment involved five different residue amounts (0, 180, 360, 720, 1 440 kg/hm2) and two types of residues (polyethylene and biodegradable residues). Through pot experiments, the study examined the impact of different residue contents on soil total nitrogen, nitrogen gas losses, nitrogen fertilizer utilization efficiency, and tomato growth indicators. [Results] The research indicates that with an increase in residue content, the cumulative emissions of ammonia and nitrous oxide in the soil show a trend of first increasing and then decreasing. When the residue content reaches 720 kg/hm2, the cumulative ammonia emission significantly decreases by 11.31% to 13.70%, and nitrous oxide emission decreases by 4.74% to 5.13%. There was no significant difference in nitrogen residue in the soil. When the residue content is below 180 kg/hm2, the residue promotes tomato growth; when the residue content is above 180 kg/hm2, it inhibits tomato growth. Low residue content has no significant effect on nitrogen fertilizer utilization efficiency. However, when the content is higher than 360 kg/hm2, nitrogen fertilizer utilization efficiency shows a negative correlation with residue content. Through comprehensive analysis, it is suggested that soil residue content should be controlled within 180 kg/hm2 to avoid negative effects on crop growth. Furthermore, due to the degradable nature of biodegradable residues, their adverse effects on nitrogen absorption by plants and nitrogen fertilizer utilization efficiency are weaker than those of polyethylene residues. [Conclusion] Therefore, replacing polyethylene residues with biodegradable residues is considered feasible.

    • WANG Kaili, ZHANG Hanyu, FANG Nufang, LIU Qianjin, LI Jingjiang

      2024,38(2):406-413, DOI: 10.13870/j.cnki.stbcxb.2024.02.010

      Abstract:

      [Objective] To explore the effects of degradable mulch film mulching on runoff and loss of dissolved nitrogen and phosphorus. [Methods] Polyethylene film mulching (PF) with a thickness of 0.003 mm, degradable film mulching with a thickness of 0.006 mm (BF1), 0.008 mm (BF2), 0.010 mm (BF3) and 0.012 mm (BF4), and no mulch (CK) were set up. In in-situ runoff plots, using mulching on ridge tillage peanut planting as the study object, the runoff and concentration of ammonium nitrogen (NH4+—N), nitrate nitrogen (NO3-—N), and available phosphorus (PO43-—P) in runoff under natural rainfall conditions were measured, and the runoff and nutrient loss characteristics under different thickness of degradable mulch film were analyzed. [Results] (1) The degradation time of degradable film increased with the increase of film thickness. (2) The order of cumulative runoff was BF1<BF2<BF3<PF<CK<BF4, and there was significant difference between BF1 and BF4 (p<0.05). (3) Compared with CK, different film mulching can reduce the cumulative loss of nitrogen and phosphorus to varying degrees. BF1 had the most significant effect on reducing the loss of NH4+-N and NO3-—N, while BF2 had the most significant effect on reducing the loss of PO43-—P. (4) Among the five laminating treatments, the NO3-—N and PO43-—P loss in BF4 treatment was the highest, while the NH4+-N loss in BF3 treatment was the highest. [Conclusion] The research results can provide a theoretical basis for the prevention and control of water, soil, and nutrient loss in sloping farmland mulching with plastic film and solving the problems of agricultural non-point source pollution, and have important significance for green agricultural development and ecological sustainable development.

    • ZHAO Le, SU Rui, HE Honghua

      2024,38(2):414-422, DOI: 10.13870/j.cnki.stbcxb.2024.02.040

      Abstract:

      [Objective] In order to explore the effects of soil phosphorus (P) fertilizer and salt and their interaction on the plant growth, P nutrition and salt tolerance of alfalfa (Medicago sativa). [Methods] Alfalfa "Gannon Ⅶ" was planted by adding phosphate fertilizer (0, 40, 80, 160 mg/kg, in the form of KH2PO4) and NaCl (0, 0.4, 0.8, 1.6 g/kg) with different concentration gradients to the loess soil. [Results] The aboveground and underground biomass of alfalfa increased with the increase of P application level, but decreased with the increase of NaCl addition level. When P was added, P uptake by plants increased. When P was added at 160 mg/kg, P concentrations in roots, stems, and leaves all reached the maximum. However, the addition of salinity inhibited the absorption of P. When NaCl was added at 1.6 g/kg, P concentrations in roots, stems, and leaves all significantly decreased, when compared with that without NaCl. The content of tartrate in rhizosphere of alfalfa decreased with the increase of P compared with that without P, and the addition of exogenous salt significantly increased the content of tartrate in rhizosphere. The rhizosphere soil pH of most treatments was lower than that of non-rhizosphere pH, the decrease of soil pH under salt stress might increase the availability of soil P and P uptake by plants. A high-dose (160 mg/kg) of P significantly reduced the P-uptake efficiency of P-utilization efficiency of alfalfa. [Conclusion] In summary, there was a significant interaction between soil P fertilization and salinity, and the increase in salinity exacerbated plant P deficiency. Appropriate application of P-fertilizers can improve the salt tolerance of alfalfa and enhance its productivity in saline soils.

    • LI Jingang, HE Pingru, CHEN Jing, ZHANG Na, DU Bin, LIU Chuang, ZHOU Mingqiang

      2024,38(2):423-436, DOI: 10.13870/j.cnki.stbcxb.2024.02.036

      Abstract:

      [Objective] To explore the optimal salt composition and salt concentration of irrigation water suitable for tomato field cultivation in arid and semi-arid areas. [Methods] Three salinity levels (1, 2, and 3 g/L) and five Na∶Ca molar concentration ratio levels (1, 3, 5, 7, and 9) of irrigation water were used in a 3-year field experiment of drip irrigation under tomato film in Yinbei irrigation district of Ningxia, China. [Results] The experiment found that with lower irrigation water salinity (1 g/L), appropriate increases in the Na∶Ca molar ratio of irrigation water were beneficial for the accumulation of tomato plant dry matter and nutrients. Tomato fruit weight, marketable yield, and total yield decreased linearly with the increase of irrigation water Na∶Ca molar ratios. Moreover, with each increase in Na∶Ca molar ratio of irrigation water, the tomato marketable yield decreased by 5 761.7 to 6 036.7 kg/hm2. Irrigation water with "high salinity (2, 3 g/L) and low Na∶Ca molar ratio (1 and 3)" was more profitable for tomato yield increase than irrigation water with "low salinity and high Na∶Ca molar ratio". The soil sodium adsorption ratio in 0—40 cm and the amount of soil salt accumulation in 0—100 cm increased linearly with the increase of irrigation water Na∶Ca molar ratio. [Conclusion] To alleviate the soil salt accumulation and obtain a relatively high fruit yield during the growth period of field cultivated tomatoes in Yinbei irrigation area of Ningxia, irrigation water with salinity of 2 g/L and Na∶Ca molar concentration ratio of 5 was recommended for mulched drip irrigation, under the control limit of soil matrix potential at -20 kPa.

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    • Multi scenario simulation of land use and carbon stock assessment in the Pearl River Basin in the next decade

      lanjian

      Abstract:

      [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.

      • 1
    • The Effect of Wind Speed on the Characteristics of Rill Erosion on Windward Slope under Rainfall Conditions

      Zhang Wenbo, Han Yuguo

      Abstract:

      [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.

      • 1
    • Effects of biocrusts on water evapotranspiration of shrub-grass ecosystem in water-wind erosion crisscross region of Loess Plateau

      zhangxudong, zhaoyunge

      Abstract:

      Evapotranspiration is the main way of soil water loss. However, as a widely distributed surface cover in arid and semi-arid regions, how biocrusts (biological soil crusts) affect ecosystem evapotranspiration was still not clear to date. Thus, we investigated the effect of biocrusts on evapotranspiration of shrub-grass ecosystem in water-wind erosion crisscross region of Loess Plateau by using soil columns in the study. The bare soil column was used as control, and three treatments were set up, they were shrub-grass (single plant shrub-20% grass), shrub-grass-30% biocrust and shrub-grass-50% biocrust. The results showed that after 12 hours of simulated 30 mm precipitation infiltration, the water content of 0 ~ 20 cm soil layer in the shrub-grass-biotic crust treatment was 15.4 % higher than that in the bare soil treatment and 12.8 % higher than that in the shrub-grass treatment. Compared with bare soil, shrub-grass and shrub-grass with different coverage biocrusts significantly increased soil water dissipation. Among them, shrub-grass treatment increased by 120.3 % compared with bare soil, and shrub-grass-biocrust increased by 116.5 % on average compared with bare soil. The biological crust reduced the water dissipation of the shrub-grass ecosystem. Compared with the shrub-grass treatment, the water dissipation of the shrub-grass-biological crust decreased by 1.7 % on average, and the degree of reduction was related to the coverage, time period and soil depth of the biological crust. Among them, the water dissipation of shrub-grass-30 % biological crust and shrub-grass-50 % biological crust treatments increased by 5.3 % and decreased by 8.7 %, respectively, compared with shrub-grass treatment. The effect of biological crusts on the reduction of water dissipation in shrub-herb ecosystem was obvious in 1-4 days after rain. Biological crusts mainly reduce evapotranspiration and evapotranspiration rate by reducing water dissipation in the soil layer below 20 cm of shrub-grass ecosystem. Compared with the shrub-grass treatment, the evapotranspiration loss of 0-20 cm soil layer in the shrub-grass-biotic crust treatment increased by 14.4 %, and the water dissipation in the soil layer below 20 cm decreased by 15.5 %. This paper further improves the study of the effect of biological crusts on soil moisture and provides a scientific basis for improving the accuracy of evapotranspiration model prediction.

      • 1
    • Spatial and temporal variation and potential of NPP in terrestrial ecosystems in Shaanxi Province from 2000 to 2020

      Wang, wang, DengLei

      Abstract:

      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.

      • 1
    • Identification of key areas for ecological restoration and division of restoration zones in Qinghai Province

      MA Zeyu, LI Peng

      Abstract:

      [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.

      • 1
    • Spatial and temporal variation characteristics of vegetation greenness in rocky desertification and non-rocky desertification areas of Chongqing

      LI Hui, WEI Xingping

      Abstract:

      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

      Abstract:

      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

      Abstract:

      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

      Abstract:

      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

      Abstract:

      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

      Abstract:

      [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

      Abstract:

      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

      Abstract:

      [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

      Abstract:

      [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

      Abstract:

      [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

      Abstract:

      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

      Abstract:

      [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

      Abstract:

      [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

      Abstract:

      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

      Abstract:

      [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

      • 1
    • 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

      Abstract:

      [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.

      • 1
    • Analysis of Hydrological Characteristics and Influencing Factors of Typical Lakes in the Qinghai Tibet Plateau from 1985 to 2021

      zhangjiaqi, zhanghuilan

      Abstract:

      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.

      • 1
    • 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

      Abstract:

      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.

      • 1
    • The impacts of extreme climate events on vegetation dynamics in the Qinling-Daba Mountains

      CHEN Chaonan, ZHU Wenbo

      Abstract:

      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.

      • 1
    • Multi-scenario Simulation and Water Resource Effects of Integrated Utilization of Saline-alkali Land in Western Jilin Province

      liwenbo

      Abstract:

      [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.

      • 1
    • Regulatory mechanisms of nitrogen and phosphorus transformation and maize growth in soils of the black soil zone: based on field experiments

      gongpinxiang, fuqiang

      Abstract:

      [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 tillage + 3t/hm2 biochar (D3), 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 deep 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 of biochar 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’

      Abstract:

      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

      Abstract:

      [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

      Abstract:

      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

      Abstract:

      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..

      • 1
    • Modeling and Analysis of Hydraulic Erosion in Slope Farmland Using Gradient Lifting Tree Model

      litongliang

      Abstract:

      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

      Abstract:

      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

      Abstract:

      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

      Abstract:

      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

      Abstract:

      [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

      Abstract:

      [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

      Abstract:

      [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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Editor in Chief:LIU Baoyuan
Founded in:1987
Governing Body:Chinese Academy of Sciences
Sponsor:Institute of Soil and Water Conservation, CAS & MWR;
Soil Science Society of China
Publisher:Editorial Department of Journal of Soil and Water Conservation
Phone:029-87012707
029-87010802
Address:Editorial Department of Journal of Soil and Water Conservation, No. 26 Xinong Road, Yangling District, Shaanxi Province, China
Postcode:712100
Email:stbcxb@nwsuaf.edu.cn
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