Abstract:［Objective］This study aimed to explore the characteristics and functions of water conservation in karst regions， in order to provide theoretical support for understanding its intrinsic mechanisms and improving comprehensive assessment methods.［Methods］The conceptual development，ecological functions，assessment techniques，and research methods of water conservation were reviewed. Based on the ecological，geological，and hydrological characteristics of karst regions， the unique features and ecological functions of karst water conservation were discussed，insights and recommendations for future research were offered.［Results］1）Karst water conservation significantly differs from non-karst areas in terms of rock-soil structure，hydrogeological conditions，and eco-hydrological processes. 2）The main functions of karst water conservation include water storage，regulation，and supply. 3）Suggest utilizing high-precision geophysical detection technologies to enhance quantitative research on karst subsurface structures，improving understanding of karst underground systems，and strengthening research on the influence of karst subsurface structures on hydrological processes and water conservation capacity，and quantify their contributions to water conservation. Based on the characteristics of karst subsurface structures and the spatial development patterns of aquifers，optimizing existing models and developing new evaluation methods based on long-term watershed monitoring data from karst regions. Increasing awareness and emphasis on the importance of karst underground water conservation and advocating for its prioritization， suggesting that water conservation should be considered as equally critical as soil conservation in karst regions. ［Conclusion］Future research on karst water conservation should focus on subsurface hydrological processes， integrate multidisciplinary approaches to improve the karst water conservation assessment system and advance both theoretical and practical applications.

Abstract:［Objective］This study aimed to explore the effects of tillage practices on soil organic carbon loss/leaching process and their coupled synergistic mechanism in red soil slope farmland，and to provide a scientific basis for regulating soil organic carbon loss/leaching by optimizing tillage practices in red soil slope farmland. ［Methods］Four tillage practices were established，including plastic film mulching（PM），cross-slope ridge tillage（RT），downslope ridge tillage（DT）and conventional tillage（CT）. A refined indoor rainfall simulation experiment was conducted，and structural equation model（SEM）was employed to analyze the mechanism by which different tillage practices influence the process of soil organic carbon loss/leaching of the red soil slope farmland under the effect of rainfall erosion.［Results］The surface runoff and interflow under different tillage practices were ranked as PM>DT>CT>RT，and RT>CT>DT>PM，respectively. Among them，surface runoff accounted for 60.6%，34.9%，53.4% and 45.8% of the total runoff in PM，RT，DT and CT plots. The runoff form of PM and DT was mainly surface runoff，while the runoff form of RT and CT was mainly interflow. The runoff，sediment yield，and organic carbon loss/leaching were significantly affected by the interaction of tillage practices，crop growth stage，and rainfall intensity（p<0.01）. Among them，the total sediment yield of DT was the largest，which was 2.00-8.28 times higher than those of other tillage practices（p<0.05）. The soil organic carbon loss/leaching under different tillage practices and growth stages followed the order of DT>CT>PM>RT，and heading stage>flowering-grain stage>seedling stage. RT significantly reduced organic carbon loss/leaching by 4.9% to 52.8% compared to other tillage practices（p<0.05）. The loss/leaching of organic carbon through surface runoff，interflow，and eroded sediment accounted for 56.1%，18.1% and 25.8% of the total loss， respectively. SEM analysis showed that tillage practice and rainfall intensity indirectly affected soil organic carbon loss/leaching process by affecting surface runoff，interflow，and sediment yield. Among them，the influence of surface runoff was the greatest，followed by sediment yield and interflow.［Conclusion］Surface runoff and erosion sediment are the main ways of soil organic carbon loss/leaching in red soil slope farmland. RT has significant advantages in reducing surface runoff，sediment yield，and controlling soil organic carbon loss/leaching in red soil slope farmland，making it a preferable tillage practice for sustainable management of red soil slope farmland.

Abstract:［Objective］This study aimed to analyze the channel characteristics in a typical small watershed in the black soil region in northeast China，and to explore the methods for distinguishing gullies and stream channels. ［Methods］A small watershed（14.59 km²）in the typical black soil region of Bin County，Heilongjiang Province， was selected as the study area. Based on drone imagery and the high-resolution digital elevation model，the Strahler's stream order method was used to classify permanent channels.［Results］The channel density in the watershed was 3.87 km/km²，and the number of channels in the small watershed decreased exponentially as the stream order increased. The proportion of level 1 channels was the highest（64.60%），while the length and area of level 2 channels accounted for the largest proportion，37.62% and 29.57%，respectively. Channels at levels 4 and above had significantly greater width，length，and area than those at lower levels. Channel depth gradually increased from level 4 to level 6. The cross sections of channels at levels 1 to 3 were primarily "V"-shaped or "V"- "U"-shaped. All level 1 to 3 channels were classified as erosion gullies，and level 5 and 6 channels were classified as steam channels，while level 4 channels exhibited characteristics of both.［Conclusion］The Strahler stream order method is applicable for classifying channels in small watersheds of black soil regions. Erosion gullies and stream channels show distinct morphological differences. The findings provide a reference for erosion classification and management.

Abstract:［Objective］In order to explore the characteristics and influencing factors of snowmelt erosion on contour-ridge farmland in the black soil region of northeast China，a study was carried out to monitor the snowmelt process on farmlands with the same slope gradient but different slope lengths in the Mahuagou small watershed in Mudanjiang City，Heilongjiang Province. The aim was to explore the patterns and dynamics of such erosion process.［Methods］During the spring snowmelt season，the snowmelt erosion process was investigated on contour-ridge farmlands with three distinct slope lengths（5，20 and 100 m）. The changes in snow depth，runoff rates，sediment concentration，total runoff，and sediment yield were analyzed.［Results］1）Snow depth showed a significant downward trend during the snowmelt period，with a faster decrease in the mid-melt phase，and a relatively slow decrease in the initial and final phases. The complete melting times for slopes of 5，20 and 100 m length were 5，6 and 6 days，respectively. 2）During the snowmelt process，the 100 m slope started to produce runoff around 9：30 every day and stopped around 17：30；the runoff generation times for the 5-m and 20-m slopes were about an hour later，and the runoff generation ended about an hour earlier. The cumulative runoff durations for the 5，20 and 100 m slopes were 5，6 and 7 days，respectively. The runoff rate and sediment concentration both initially increased and then decreased，and both increased with increasing slope length，with the peak sediment concentration lagging behind the peak runoff rate by approximately 0 to 2.0 hours. 3）During the snowmelt process，the daily total runoff and sediment yield followed the order of 100 m slope> 20 m slope > 5 m slope，and they both initially increased and then decreased on all slopes.［Conclusion］During the snowmelt process，the patterns of change in snow depth，runoff，and sediment production exhibit similarities across various slope lengths. As slope length increases，there is a corresponding increase in runoff duration，runoff rate，sediment concentration，total runoff，and sediment yield. Investigating the snowmelt erosion process on contour-ridge sloping farmlands with different slope lengths offers valuable theoretical insights for mitigating soil and water loss on sloping farmland in the black soil region of northeast China.

Abstract:［Objective］ This study aimed to comprehensively analyze the spatial distribution and dominant influencing factors of soil erosion in the Three-River Headwater Region for ensuring regional ecological security. ［Methods］The average erosion rate for four decadal periods from 1983 to 2022 was simulated using a regionalscale process-based erosion model，PESERA. The optimal Parameters-Based Geographical Detector（OPGD） method was employed to evaluate the explanatory power of individual factors on erosion rates and the interactions between multiple factors.［Results］The accuracy of PESERA modelling results was acceptable in the Three-River Headwater region（NSE = 0.53，R² = 0.69）. The spatial distribution of erosion rates showed a gradual decrease from south to north. Severe erosion［> 150 t∕（hm²·a）］，mild erosion［< 5 t∕（hm²·a）］，and slight erosion［5-25 t∕（hm²·a）］were mainly concentrated in the headwater area of Lancang River（southern part of the study region），the headwater area of Yangtze River（northwestern part of the study region），and the headwater area of the Yellow River（eastern part of the study region），respectively. Other erosion intensities were mainly distributed across the southern parts of the Three-River Headwater Region. The analysis of individual factor detection revealed that terrain relief（0.43）and precipitation（0.35）were the most influential factors. Interaction analysis indicated that the combination of precipitation and vegetation cover had the highest explanatory power （0.73），while the interaction between terrain relief and other factors considerably enhanced their effects on erosion rates.［Conclusions］Between 1983 and 2022，mild erosion was the dominant type of soil erosion in the Three-River Headwater Region. Temporally，erosion rates exhibited an initial increasing trend followed by a subsequent decline. The main factors affecting soil erosion in the region were terrain relief，precipitation，and vegetation cover. The findings can provide valuable insights for soil conservation and ecological protection in the Three-River Headwater Region.

Abstract:［Objective］To clarify the change characteristics of nitrate export flux and pattern driven by rainfall. ［Methods］Typical subtropical hilly watershed Longyan small watershed in Hunan Province was chosen as the research object. By monitoring the dynamic changes of watershed runoff and nitrate concentration with high frequency and combining with the C-Q relationship model，the differences in nitrate export flux and patterns among different rainfall types were clarified. On this basis，the key influencing factors of nitrate export were identified by using redundancy analysis and correlation analysis.［Results］The weighted average concentration of runoff nitrate of all rainfall events varied from 0.08 to 1.50 mg/L. Among them， the weighted average concentration of light rain events was only 0.35 mg/L，and the weighted average concentrations of heavy rain and rainstorm events werre 1.68 and 2.97 times that of light rain events，respectively. The variation range of nitrate export flux in rainfall events was 4.27-353.85 g/h，among them，the average export flux of moderate rain events was only 20.39 g/h，while the average export flux of heavy rain and rainstorm events was as high as 185.08 and 194.49 g/h， respectively. In the watershed， the main nitrate export pattern was the enrichment pattern， accounting for 75%. The variability of nitrate export patterns decreased with the increase of event intensity. The results of redundancy analysis and correlation analysis showed that，compared with rainfall duration，rainfall intensity and other factors，rainfall，rainfall within three days before the event and initial discharge were the key factors affecting watershed nitrate export，and their explanatory rates for nitrate export characteristics were 33.8%，17.1% and 13.1%，respectively. Among them，rainfall was significantly positively correlated with nitrate concentration and nitrate export flux（p<0.01 and p<0.05），and rainfall within three days before the event was significantly positively correlated with the nitrate export pattern（p<0.05）.［Conclusion］The combined action of rainfall，antecedent rainfall，and initial discharge changes the source and path of nitrate transport，making nitrate export more complicated. Scientific understanding of the patterns of nitrate export driven by rainfall is of great scientific significance to guide the prevention and control of non-point source pollution in the watershed.

Abstract:［Objective］To investigate the effects of intermittent rainfall conditions on the pore structure and aggregate turnover in the black soil topsoil.［Methods］Black soil topsoil was studied using a combination of rare earth element tracer method，artificial rainfall simulation，and CT scanning research method. The aim was to elucidate the responses of topsoil aggregate characteristics，turnover characteristics of topsoil aggregates，and topsoil pore characteristics to rainfall intensity and frequency.［Results］Under intermittent rainfall conditions， isolated pores were concentrated in the topsoil layer. With the increase of the number of rainfall events，the connected porosity was always greater than the isolated porosity at a rainfall intensity of 40 mm/h，and the maximum values of connected porosity and isolated porosity alternated at a rainfall intensity of 70 mm/h. For large aggregates，as the number of rainfall events increased，the ability of 5-2 mm aggregates to break up into 0.25-0.053 mm aggregates decreased when the connecting porosity decreased，while the ability of 5-2 mm aggregates to break up into <0.053 mm aggregates increased. The opposite was true when the connectivity porosity increased. For small aggregates，as the number of rainfall events increased，the ability of 0.25-0.053 mm aggregates to break up into <0.053 mm aggregates increased，while the ability of <0.053 mm aggregates to aggregate to form 0.25-0.053 mm aggregates gradually decreased.［Conclusion］With the increase in the number of intermittent rainfall，isolated pores tend to concentrate in the topsoil layer. Meanwhile，the ability of large aggregates to break up into small particle sizes gradually increases，while the ability of small aggregates to form large aggregates gradually decreases.

Abstract:［Objective］This study aimed to investigate the influence of rainfall intensity on runoff production of the slope of accumulation body of earth-rock mixing engineering in karst areas，in order to provide a deeper scientific basis for the study of hydrological characteristics and theoretical reference for ecological restoration of the accumulation.［Methods］The experimental materials were obtained from typical accumulation body of earth-rock mixing engineering in the study area，and runoff production characteristics of the engineering accumulation with typical slope（30° ）and gravel content（30%）were studied at different rainfall intensities（50，70，90 and 110 mm/h）by using indoor simulated rainfall experiment.［Results］1）The runoff production on the slope of the accumulation body of earth-rock mixing engineering included three types，namely surface runoff，interflow，and subsurface runoff，with interflow and subsurface runoff being the dominant forms. The proportion of surface runoff production decreased with the increase of rainfall intensity. 2）Surface runoff on the slope of the engineering accumulation body changed with the time of rainfall，first increased rapidly，then gradually decreased，and then gradually stabilized over time，with peak values appearing about 30 min after the start of rainfall. The interflow increased first and then stabilized over time，with the stabilization point delayed with the increase of rain intensity， showing a smoother trend compared to surface runoff. Subsurface runoff generally increased first and then decreased，with most of the turning points occurring between 70 and 90 min after the start of rainfall. 3）There was a significant positive correlation between rainfall intensity and runoff production of all runoff types on the engineering accumulation slope（p<0.01），and all correlation coefficients were above 0.7.［Conclusion］The runoff production on the slope of the accumulation body of earth-rock mixing engineering in karst areas includes surface runoff，interflow，and subsurface runoff，among which interflow and subsurface runoff are dominant. Changes in rainfall intensity have a significant impact on the runoff production on the accumulation slope，and the runoff of each type increases with the increase of rainfall intensity.

Abstract:［Objective］This study aimed to elucidate the characteristics of slope runoff paths and microtopography changes under continuous rainfall conditions，as well as their impact on erosion and sediment yield.［Methods］Indoor artificial simulated rainfall experiments were conducted on typical loessial soil slopes in western Shanxi Province，with rainfall intensities of 30，60 and 90 mm/h，a slope length of 3 m， width of 1 m，and gradient of 15°.［Results］The runoff generation rate increased from 144.84 mL/（min·m²）to 978.02 mL/（min·m²）with the increase of rainfall intensity，and the time to reach stability decreased from 24 min to 15 min as rainfall events increased. In terms of sediment yield，there were significant differences in the variation trend of sediment yield rate under different rainfall intensities. Under the rainfall intensity of 30 mm/h，the average sediment yield rate increased gradually from the initial 0.08 g/（min·m²）with the extension of runoff duration and then tended to be stable（0.13-0.42 g/（min·m²））. In contrast，under the rainfall intensity of 60 and 90 mm/h，the average sediment yield rate decreased gradually from 2.02 g/（min·m²） to 2.76 g/（min·m²），and then stabilized at 0.55-0.99 g/（min·m²）and 0.50-0.83 g/（min·m²）. Under 30 mm/h rainfall，the distribution of runoff paths on the slope was relatively random. After the fourth rainfall event at 90 mm/h，a main flow path with a length of 4.45 m formed and extended through the entire slope. The degree of runoff connectivity increased，and the flow paths developed steadily. The values of surface roughness and cutting degree increased from the upper to the lower part of the slope，and the proportion of high-value areas increased from 33.09% and 18.74% to 53.63% and 30.80%，respectively，as rainfall intensity increased.［Conclusion］The results provide a scientific basis for a deeper understanding of the runoff connectivity process and micro-topography changes on loessial soil slope surface in western Shanxi Province under continuous rainfall conditions，as well as for soil erosion control.

Abstract:［Objective］Exploring the characteristics of slope erosion on typical lateritic slope farmland in northern Guangdong is of great significance for local soil and water conservation and sustainable agricultural development. ［Methods］Taking the lateritic soil from slope farmland in the Nanxiong basin of northern Guangdong as the research object，the characteristics of runoff and sediment yield on the lateritic slope under individual rainfall events were analyzed based on artificially simulated rainfall experiments with three slope gradients（5°，10° and 15°）and five rainfall intensities（80，90，100，110 and 120 mm/h）.［Results］1）The initial runoff time of a gentler lateritic slope（5°）was 2-10 s longer than that of a steeper slope（10°，15°），and the influence of rainfall intensity on the initial runoff time was greater than that of slope gradient. 2）The runoff of steeper slopes was greater than that of gentler slope. The slope runoff of the three different slopes and five different rainfall intensities ranged from 22.86 to 34.78 L. The impact of rainfall intensity on slope runoff was greater than that of slope gradient. 3）The sediment yield rate of lateritic slope was relatively high at the early stage of runoff，and then tended to fluctuate and stabilize. Under the same slope gradient，the greater the rainfall intensity，the greater the sediment yield of slope erosion；under the same rainfall intensity，the greater the slope gradient，the greater the sediment yield. The maximum sediment yield occurred at the actual rainfall intensity of 119.5 mm/h and a slope gradient of 15°. 4）The sediment yield of lateritic slope was influenced by rainfall，rainfall intensity，runoff，and slope gradient，and the sediment yield was significantly positively correlated with runoff and rainfall，with a coefficient of determination （R²）above 0.56.［Conclusion］The initial runoff time on lateritic slope farmland is related with rainfall intensity and slope gradient，decreasing with increasing rainfall intensity and slope gradient. Both slope runoff and sediment yield increase with the increase of slope gradient and rainfall intensity. The relationships between slope sediment yield and runoff，rainfall，and rainfall intensity can be fitted using linear or quadratic function equations，with high coefficients of determination.

Abstract:［Objective］The relationship between annual runoff and sediment load in the Upper Yangtze River basin （UYRB）had a significant change under the operation of large reservoirs. There was no obvious variation in the annual runoff processes in the UYRB，while the annual sediment load decreased greatly.［Methods］Based on the annual runoff and sediment load observation series in the mainstream and main tributaries in the UYRB during 1950—2022，improved double mass curve method was utilized to calculate the deviation sequences of the double mass curves and introduce the scaling factors，thereby analyzing the cumulative mutation characteristics of the relationship between annual runoff and sediment load.［Results］The relationship between annual runoff and sediment load in the UYRB had significantly changed in 1985，1998，2002 and 2013，respectively. As a result， the average sediment content in the UYRB decreased from 1.20 kg/m³ to 1.02，0.77，0.12，0.03 kg/m³， respectively. Combined with the distribution of large reservoirs in the river network，the four mutations in the relationship between annual runoff and sediment load in the UYRB were caused by the operation of Baozhusi Reservoir and Wujiangdu Hydropower Station，Ertan Reservoir，Three Gorges Dam，Xiangjiaba and Xiluodu Reservoir. Operation of large reservoirs led to a reduction of annual sediment load by 515 million tons in the upstream，with a 97.17% sediment reduction rate in the upstream.［Conclusion］Improved double mass curve method can effectively quantify the cumulative change in the relationship between runoff and sediment load and identify mutation points across multiple temporal scales. The mutations in the relationship between annual runoff and sediment load in the UYRB were predominantly driven by sediment interception from reservoir groups，while the spatiotemporal superposition effects of reservoirs in both tributaries and the mainstream further intensified the cumulative variations. The research findings can provide a theoretical basis for regulation of runoff and sediment load in the basin.

Abstract:［Objective］The study aimed to investigate the effects of rice straw biochar on water infiltration and evaporation characteristics in compacted soils in mining areas，and to provide a basis for resource utilization of straw waste and soil remediation in mining areas.［Methods］Indoor soil column simulation test was conducted under simulated compaction treatments of 1.2，1.3，1.4，1.5 and 1.6 g/cm³（T_1.2 - T_1.6）at four different biochar application rates（0，2%，4% and 6%）.［Results］1）Different application rates of biochar all slowed down the downward migration rate of wetting front in different compacted soils. The cumulative infiltration of soil moisture increased first and then decreased with the increase of biochar application rate. The 2% biochar treatment increased the cumulative infiltration across all compaction treatments，with T_1.2，T_1.3，T_1.5 and T_1.6 showing increases of 10.73%，2.99%，11.96% and 2.39%，respectively，compared to the no-biochar treatment（p<0.05）. When the application rate was increased to 6%，the cumulative infiltration for all compaction treatments was less than that of the 2% biochar treatment. 2）Power function Power function provided a good fit for the wetting front movement in biochar-amended compacted soils. The Horton model was the most suitable for estimating the cumulative infiltration in biochar-amended compacted soils. 3）Biochar affected both stages of the evapotranspiration process of compacted soils，significantly affecting the rapid evaporation stage（p<0.05），resulting in a reduction in total evapotranspiration. The residual water content in soils with different compaction degrees significantly（p<0.05） increased at all biochar application rates compared to soils without biochar. 4）Compaction was the main factor affecting soil water infiltration and evaporation. The F-values under the interaction of biochar and compaction were reduced compared to compaction treatments alone.［Conclusion］The application of 2% biochar is most effective in improving the moisture availability in compacted soils in mining areas. The results of this study provide a scientific basis for using biochar to improve the hydrological process and soil remediation of compacted soils in mining areas.

Abstract:［Objective］The effects of soil physical properties on preferential flow vary significantly across regions. This study aimed to clarify the mechanisms to provide practical implications for assessing forest hydrological effects and guiding sustainable forest resource management.［Methods］Three forest stands（oak forest，pine forest，and bamboo forest）in Kongqingshan，Jiangsu Province，were selected. Dye-tracing experiments under simulated rainfall（50 mm/h）were conducted，and soil preferential flow patterns were analyzed using soil physical property measurements and image processing techniques.［Results］1）Significant preferential flow phenomena were observed in the soils of all forest stands（p<0.05）. The dyeing area ratios in different soil layers were 41.54%-90.00%，9.27%-90.11% and 18.19%-93.93% for oak forest，pine forest，and bamboo forest， respectively. The fractal dimensions of dye-stained patches were 1.23-1.59，1.62-1.96 and 1.68-1.97， respectively. The number of dye-stained patches were 2-12，13-160 and 22-360，respectively，with significant differences （p<0.05）. The widths of dye-stained patches were 2.50-3.27， 0.47-3.24 and 0.37-2.59 cm， respectively，with significant differences（p<0.05）. The preferential flow ratios were 91%±3%，27%±7% and 51%±7%，respectively，with significant differences（p<0.05）. The matrix flow depths were（14.5±7.3）， （17.9±3.9）and（16.8±3.8）cm，respectively. 2）In all three forest stands，the dyeing area ratio was negatively correlated with soil bulk density（p<0.001）and positively correlated with total porosity（p<0.05）. The fractal dimension of dye-stained patches was positively correlated with soil moisture content（p<0.001）. The number of dye-stained patches was positively correlated with clay content（p<0.05），while the width of dye-stained patches was negatively correlated with soil moisture content. 3）The dyeing area ratio and the fractal dimension of dyestained patches，as key parameters of preferential flow，showed high goodness-of-fit when modeled with soil physical properties using multiple linear regression equations. These two parameters were relatively more important in their correlations with soil bulk density and porosity.［Conclusion］The soil infiltration properties at different depths of oak forest，pine forest，and bamboo forest exhibited significant differences. Soil bulk density and total porosity are key drivers of preferential flow development.

Abstract:［Objective］To determine the influence of sample characteristics such as sample size，sample shape， and sample type on the shear strength of granite residual soil.［Methods］A series of large-scale direct shear tests were carried out on granite residual soil by using a large-scale direct shear instrument. Based on the shear stress-displacement curve，shear strength and its parameters，the influence of the above-mentioned sample characteristics on the strength characteristics of granite residual soil was studied，and a recommendation was provided for determining strength parameters in practical engineering applications.［Results］Both the shear strength and its parameters of granite residual soil decreased first and then tended to stabilize as the sample size increased. The soil strength obtained under the optimal sample size could effectively overcome the influence of size effect on the test results. The shear strength and cohesion of square samples were smaller，while the internal friction angle was larger，than that of cylindrical samples. The non-uniformity of stress distribution speeded up the failure process of square samples. The shear strength of the original sample was significantly higher than that of the reconstructed sample，and the difference in shear strength between the original sample and reconstructed sample decreased with the increase of normal stress. The exponential function can be used to well describe the relationship between sample strength and sample size.［Conclusion］In practical engineering applications，large-diameter samples or small-diameter samples considering shear strength error should be used for large-scale direct shear test to obtain strength parameters that are better in line with practical engineering.

Abstract:［Objective］This study aimed to analyze the temporal and spatial variation characteristics of soil moisture on the northern slope of the Tianshan Mountains and its influencing factors，with a focus on examining the impact of cropland expansion on soil moisture. ［Methods］ Based on 1 km daily soil moisture data， land use data， meteorological data，and other datasets from 2000 to 2020，the Theil-Sen Median trend analysis，Mann-Kendall significance test，and Pearson correlation analysis were employed to investigate changes in soil moisture within the 0-50 cm soil layer. Additionally，the Geodetector model was used to identify the main factors influencing soil moisture and their spatial differentiation characteristics.［Results］From 2000 to 2020，soil moisture in the 0-50 cm layer on the northern slope of the Tianshan Mountains exhibited an overall decreasing trend，with the most significant changes observed in the 0-10 cm layer. Under different land use types，soil moisture in croplands decreased significantly，while changes in forestlands and unused lands were not significant，and grasslands showed a slight increase in soil moisture. The average soil moisture followed the order of forestlands>grasslands>croplands> unused lands. Spatially，soil moisture decreased in most areas，but increased in the northern，southern，and eastern regions of the studied area. Soil moisture generally showed a downward trend across different elevation ranges，but gradually increased with rising elevation. When unused lands were converted to croplands，soil moisture increased at all depth levels，particularly at the 0-10 cm depth. The reduction in soil moisture was relatively small when grasslands were converted to croplands，whereas the decrease was more pronounced across all depth levels when forestlands were converted to croplands，particularly at the 40-50 cm depth. Vegetation type，precipitation，and potential evapotranspiration had the greatest impact on soil moisture，with influence values of 0.63，0.57 and 0.51， respectively. Among these factors，the interaction between precipitation and vegetation type had the most significant effect on the spatial heterogeneity of soil moisture.［Conclusion］From 2000 to 2020，soil moisture on the northern slope of the Tianshan Mountains showed a declining trend，with over 80% of the area experiencing a decrease in soil moisture. Soil moisture decreased significantly in croplands，it also declined when forestlands and grasslands were converted to croplands. Soil moisture variation was primarily significantly influenced by the interaction between precipitation and vegetation type.

Abstract:［Objective］To explore the relationship between the characteristics of soil strength and soil pore in the tidal flat reclamation areas under in-situ conditions.［Methods］Taking the soils in different reclamation areas of the coastal tidal flats in Jiangsu Province as the research object，the relationships among soil structure，in-situ soil shear strength （C_u） and sensitivity （S_t） were analyzed through in-situ vane shear tests and CT scanning technology.［Results］The S_t values in Binhai（BH）and Rudong（RD）were between 1.3 and 5.4，falling within the range from medium sensitivity（2-4）to sensitivity（4-8）. However，for the disturbed soil in these two places，the S_t values showed no significant changes under different depths and reclamation years. In contrast，the S_t values of the disturbed soil in Dongtai（DT）varied significantly. The S_t values in each soil layer were higher than those at BH and RD. Among them，the S_t value at DT1 was the highest，and the S_t value at BH3 was the lowest. The analysis of soil mechanical properties indicates that there was a positive correlation between soil bulk density，clay particle content and C_u（r=0.657 and 0.782，p<0.05），while there was a negative correlation between soil porosity and C_u（r= - 0.529 and - 0.414，p<0.05）. In addition，there was a significant negative correlation between soil sensitivity（St）and fractal dimension（FD），pore number（NOP）（r= - 0.611， p<0.05）. In the regression analysis，it is further revealed that there was a negative correlation between C_u and soil porosity，and St and NOP followed a logarithmic decreasing relationship. In the principal component analysis，the first principal component（PC1）was mainly dominated by the pore number，fractal dimension and clay content. PC2 was mainly composed of C_u and bulk density，and PC3 was jointly driven by soil porosity and soil shear strength. These indicators jointly highlight the importance of soil pore structure and physical properties in the evaluation of shear strength.［Conclusion］This study provides a scientific basis for an in-depth understanding of soil characteristics in coastal reclamation areas and offers important references for research on the stability of engineering construction，slope stability，evaluation of soil erosion resistance，and analysis of plant growth conditions in coastal areas，which is helpful to promote sustainable development of agriculture in coastal areas.

Abstract:［Objective］As a new type of soil amendment，the impact of water-storage clay on the hydraulic properties of soil on the Loess Plateau is still unknown. The aim of the study was to investigate the effects of different particle sizes and application rates of water-storage clay on soil hydraulic properties.［Methods］Silty loam from the topsoil of Xishan Mountain in Taiyuan City，Shanxi Province，was selected as the test soil for indoor physical experiment. Two particle sizes of water-storage clay（M：2-5 mm，L：5-10 mm）and four application rates of water-storage clay（0，5%，10%，20%）were set. By measuring the soil water characteristic curve and saturated water conductivity，the changes of soil hydraulic parameters under different particle sizes and application rates were analyzed.［Results］1）Compared to the control（CK），water-storage clay enhanced soil infiltration and retention capacity. The improvement in soil water retention was more pronounced with increasing application rates and particle sizes. 2）The particle size and application rate had different degrees of influence on the parameters of the Van Genuchten model. 3）With changes in the application rate and particle size of water-storage clay，the field capacity increased from 27.99% to 31.49%，the wilting coefficient increased from 5.85% to 12.66%，the air capacity increased from 19.15% to 24.68%，and saturated water conductivity increased by 96.56% to 1 150.76%. 4）The order of increase in specific water capacity was M20>L20>M10>L10>L5> M5>CK （M and L represent particle sizes of 2.5 and 5-10 mm for the water-storage clay；5，10 and 20 represent the mass application rates of 5%，10% and 20% for the water-storage clay；CK represents the control without the addition of water-storage clay）. The pore size distribution across different treatments showed the same pattern of storage pores>residual pores>transfer pores>crack pores.［Conclusion］The findings can provide theoretical support for the improvement of soil and water conservation on the Loess Plateau by adding water-storage clay.

Abstract:［Objective］The aim of this study was to reveal the species composition，community structure，and growth characteristics of herbaceous plants in the understory of mixed plantations in loess hilly areas，and to explore the impact of herbaceous plants on water interception in the understory，in order to provide a theoretical basis for ecological restoration and future forest management in the region. ［Methods］ A combination of field surveys and laboratory analysis was conducted in Wuqi County，Shaanxi Province. A pure Robinia pseudoacacia forest was selected as the control group to investigate the vegetation characteristics of the herbaceous layer and their effects on herbaceous interception under five different mixed plantation models （R. pseudoacacia×Armeniaca sibirica， R. pseudoacacia×Prunus mongolica， R. pseudoacacia×Pinus tabuliformis，R. pseudoacacia ×Hippophae rhamnoides，R. pseudoacacia×Caragana korshinskii）.［Results］1）Compared to pure R. pseudoacacia forest，mixed plantations significantly increased the species richness of understory herbaceous plants. The R. pseudoacacia×P. tabuliformis mixed plantation displayed the highest Margalef richness index. However，mixed plantations reduced the species evenness of understory herbaceous plants，with the R. pseudoacacia×P. tabuliformis mixed plantation showing the lowest Pielou evenness index. Different mixed plantations substantially increased species richness but slightly decreased species evenness. 2） Coverage and leaf area index （LAI） of the herbaceous layer varied significantly among different mixed plantation models. The herbaceous interception capacity of mixed plantations was generally lower than that of pure R. pseudoacacia plantation，with the R. pseudoacacia×P. tabuliformis mixed plantation showing the lowest interception capacity. 3）A significant positive correlation between herbaceous layer coverage and interception capacity was found，indicating that higher coverage provides a more effective rainwater interception function.［Conclusion］ While mixed plantation models improve the species diversity of understory vegetation，they may have a slight negative effect on the soil and water conservation capacity of the herbaceous layer，particularly in terms of rainwater interception by the herbaceous layer. Pure R. pseudoacacia plantations，in contrast，exhibit greater potential for rainwater interception， offering important management insights for the soil and water conservation functions of plantations.

Abstract:［Objective］Constructing a rational ecological network plays a crucial role in maintaining the sustainable development of regional ecological environment.［Methods］From the perspective of main functional zones，main functional scenarios with regional differences were established for three main functional zones. The PLUS model was used to simulate the land use patterns under the main functional scenario and the natural protection scenario in 2035. By coupling the InVEST and MSPA models，the ecological sources were comprehensively identified，and the ecological corridors were extracted using the circuit theory. The methods were used to construct multi-scenario ecological networks for Yunnan Province in 2020 and 2035，and evaluate the network structure. ［Results］1）Under the main functional scenario，cultivated land and forest land were effectively managed，and the regional expansion of construction land was strengthened，better meeting the needs of coordinated regional development. 2）The spatial distribution of ecological sources was similar under different scenarios，exhibiting a characteristic of“more in the west and less in the east”，with important ecological sources accounting for over 90% under each scenario. 3）In 2020，125 ecological corridors were constructed. In 2035，under the natural development scenario and the main functional scenario，the number of ecological corridors would be 113 and 133， respectively. The density of corridors showed a decreasing trend from southwest to northeast. 4）The ecological network structure indices under the main functional scenario were superior，indicating that the ecological network constructed based on this scenario is more ideal.［Conclusion］The proposed method and application of ecological network construction based on the main functional strategy can provide theoretical support and practical references for optimizing land space and building a "pioneer of ecological civilization " in Yunnan Province.

Abstract:［Objective］To analyze the trends of vegetation carbon storage（VCS）and soil carbon storage（SCS） of natural vegetation across different climatic zones and the driving mechanisms of environmental factors on the changes of carbon storage，in order to provide a basis for the development of vegetation management strategies adapted to climate change in the study area.［Methods］By constructing a hybrid model based on the LPJ-GUESS model and the random forest method，the dynamic changes of VCS and SCS of typical natural vegetation in China from 1851 to 2100 were simulated，and the carbon storage dynamics were analyzed by combining the Mann-Kendall trend test and Sen's slope estimation method.［Results］1）The determination coefficients of VCS and SCS of natural vegetation simulated by the hybrid model were 0.83 and 0.61，respectively，and the root mean square errors（RMSEs）were 2.42 and 3.73 kg/m²，respectively，which could accurately capture the ecosystem carbon dynamics. 2）Compared to the historical period，VCS，SCS and TCS in the whole study area were excepted to increase by 44.8%-88.1%，7.5%-13.4%，and 10.4%-19.8% by the end of this century， respectively，with the largest increase in the semi-arid plateau region. The increases under different SSPs climate scenarios followed the order of SSP119< SSP245< SSP585. 3）Under different SSPs scenarios，VCS of natural vegetation increased significantly at a rate of 4.6-9.7 g/（m²·a），while the trend of changes in SCS was not significant. TCS increased significantly at a rate of 14.6 and 18.0 g/（m²·a）under the SSP245 and SSP585 scenarios，respectively. 4）The degree of influence of environmental factors on carbon storage under different SSP scenarios followed the order of SSP119< SSP245< SSP585，with VCS being more sensitive to climate change than SCS. Precipitation was identified as the main driving factor enhancing the carbon sink function of typical natural vegetation in China.［Conclusions］The hybrid model can accurately characterize carbon storage changes. Precipitation is the key factor driving the enhancement of the carbon sink function of natural vegetation across China in the future，compared to temperature and atmospheric CO₂ concentration.

Abstract:［Objective］ To analyze the effects of photovoltaic （PV） arrays on climate and soil in rocky desertification areas and the underlying mechanisms，and to provide a scientific basis for“PV+ ”initiatives and ecological restoration in rocky desertification areas.［Methods］Taking Yunnan Shilin photovoltaic power station as the research object，based on meteorological station observations and soil property measurements，we analyzed the dynamic changes in microclimate and soil physicochemical properties between PV array area and non-PV array area in dry and wet seasons through analysis of variance（ANOVA），Mantel test，and Partial Least Squares Structural Equation Modeling（PLS-SEM），in order to explore the process and mechanism of the impacts of PV modules on microclimate and soil.［Results］1）Across different seasons，PV arrays significantly affected local microclimate factors and soil physicochemical properties（p<0.05）. Compared with non-PV array areas，during the rainy season，PV array areas significantly increased air humidity（4%）and soil temperature（7%），and decreased wind speed（77%），soil moisture（10%），light intensity（59%），soil bulk density（21%）SOC （55%），TN（14%）and HN（52%）. In the dry season，PV array areas significantly increased AK（32%）and decreased wind speed（89%），soil bulk density（11%），SOC（27%）and HN（37%）. 2）Within the PV arrays， soil hydrothermal and nutrient changes were mainly promoted by light intensity，air temperature，wind speed，and pH. The PV arrays had a direct positive effect on microclimate，soil hydrothermal conditions，and soil nutrients， and at the same time，indirectly improved soil chemical properties through improving microclimate and soil hydrothermal conditions.［Conclusion］The installation of PV panels in the rocky desertification area of central Yunnan can reduce wind speed and block light，increase air humidity，maintain soil temperature and moisture， increase soil bulk density and available potassium content，thereby contributing to the improvement of ecosystem stability.

Abstract:［Objective］To explore the impact of large-scale ecological projects on the dynamics of grassland vegetation cover，and to elucidate the constraining effects of vegetation changes on ecosystem services，in order to provide a reliable scientific basis for the sustainable development of the region and the improvement of ecological restoration projects.［Methods］Taking the Xinjiang region，which is located in the arid zone，as an example， trend analysis was used to explore the impact of ecological restoration projects on vegetation cover. Based on the InVEST model and the CASA model，four grassland ecosystem services，namely，water production，carbon storage，soil conservation，and net primary productivity（NPP），were evaluated to reveal the constraining effects of vegetation cover on these services under ecological restoration projects.［Results］1）Driven by ecological restoration projects， 79.2% of regional grasslands showed positive normalized vegetation index （NDVI） residuals，and there was a fluctuating increase in grassland vegetation cover. 2）Grassland ecosystem services in Xinjiang region showed an overall upward trend. Water production and soil conservation services reached their maximum values in 2010，and then decreased，with the high-value areas clustered in the Yili River Valley and the northern side of Altai Mountains. Carbon storage and NPP services showed an increasing trend，with uniform spatial distribution of high-value areas. 3）Three constraints between vegetation NDVI and the four ecosystem services were presented as left parabolic，humpbacked，and right parabolic，respectively. The thresholds between vegetation NDVI and Carbon storage service and NPP were 0.49 and 0.35，respectively.［Conclusion］NDVI of the grassland vegetation in the growing season has shown an increasing trend，and grassland ecological restoration projects have significantly improved vegetation cover from 2000 to 2020. When vegetation cover to ecosystem services threshold reaches 0.3-0.5，grassland integrated ecosystem services can be the optimal. Future ecological restoration policies can be improved based on regional grassland vegetation cover thresholds.

Abstract:［Objective］To explore the changes in soil organic matter in the short term during vegetation restoration in bauxite mining areas and their driving factors，in order to provide basic data for rapidly increasing soil organic carbon in mining areas.［Methods］Taking a typical bauxite mining area in Guizhou Province as the research area， we analyzed soil environment，soil organic carbon and its active organic carbon components（particulate organic carbon，POC；readily oxidizable organic carbon，ROC；light fraction organic carbon，LFOC），carbon pool management index（CPMI），and the factors driving changes in soil organic carbon and its active components during the short term of vegetation restoration（recovery years include the current year，1 year，2 years and 3 years）.［Results］1）Soil organic carbon content in the bauxite mining area was low，ranging from 13.781 to 24.566 g/kg，with the proportion of readily oxidizable organic carbon to total organic carbon increasing with the recovery years. 2）Compared to the current year of recovery，short-term vegetation restoration significantly increased the carbon pool management index，with specific values ranked in the order of 3 years（39.46）>1 year （38.88）>2 years（32.26）>current year（16.65）. 3）Redundancy analysis showed that soil pH and bacterial community richness explained 40.2% and 22.8% of the variation in the content of organic carbon and its active organic carbon components，respectively.［Conclusion］During the short term of vegetation restoration in bauxite mining areas，readily oxidizable organic carbon is an important indicator of soil carbon pool，short-term vegetation restoration has increased the carbon pool management index，and the main factors influencing changes in soil organic carbon and its active organic carbon components are pH and bacterial richness.

Abstract:［Objective］Developing a rational ecological risk assessment methodology is of great significance for the establishment of ecological security patterns and the optimization of national land space planning.［Methods］Based on land use data from 2000，2010 and 2020，the PLUS model was employed to simulate land use under the natural development scenario in 2030. The InVEST model was utilized to assess four ecosystem services，i.e. water yield， carbon storage， soil conservation， and habitat quality. Four ecological risk indicators， including ecological degradation degree，transition probability，service change，and trade-off and synergy indices，were extracted to construct an ecological risk assessment model. The assessment was conducted in conjunction with the ecological security pattern of Yunnan Province to explore risk prevention strategies.［Results］1）Although the land use changes under the natural development scenario in Yunnan Province in 2030 would be different，the degree of change would be the same. The conversion between cultivated land，forest land and grassland would be obvious，and the construction land would continue to expand. In terms of spatial distribution，the natural development scenario would be similar to the historical land use data，with the degraded areas of ecological land mainly distributed around urban development and construction areas or agricultural regions. 2）The ecosystem service functions in Yunnan Province would show a pattern of "low in the east and high in the west"，with the northwest and southwest regions being high-value areas，and the central and northeast regions being low-value areas，and the overall service function showing a downward trend. The ecological service functions of Nujiang，Baoshan，Dehong and Xishuangbanna would show an increasing trend，while the trade-off and coordination indices of central and northeastern regions would be high，and the functional conflicts between ecosystem services would be obvious. 3） There would be significant spatial differences in potential ecological risks in Yunnan Province from 2020 to 2030. High-risk areas would be mainly distributed in the central Yunnan urban agglomeration，while low-risk areas would be located in the southeast and southwest. The formation of high-risk areas would be affected by natural factors such as topography and land use distribution，as well as human activities such as urban development and construction. Ecological protection measures tailored to regional specificities are needed to promote sustainable development.［Conclusion］The results can not only provide a more accurate understanding of the potential ecological risks in Yunnan Province，supply fundamental decision-making information for the establishment of ecological security patterns and ecological restoration，but also provide innovative ideas for the expansion of ecological risk assessment methodologies.

Abstract:［Objective］Under the "dual carbon" goals，exploring the spatio-temporal variations of land use carbon intensity and ecosystem services，as well as their spatio-temporal interactive correlations，can provide decision-making references for carbon emission reduction and high-quality coordinated development of ecology and economy in the region.［Methods］Taking the Poyang Lake Eco-Economic Zone as the study area，this study analyzed the spatio-temporal variations of "Land-Demographic-Economic" carbon intensity and ecosystem services at the county scale from 2000 to 2020. The decoupling index was used to calculate the interactive relationship between carbon intensity and ecosystem services，and the "3D magic cube" model was applied to comprehensively evaluate the interactive zoning of carbon intensity and ecosystem services across different dimensions.［Results］ 1）From 2000 to 2020，the "Land-Demographic" carbon intensity in the Poyang Lake Eco-Economic Zone generally exhibited a continuous upward trend，while the "Economic" carbon intensity showed a declining trend. In addition，various ecosystem services also experienced varying degrees of decline. 2）There was a spatio-temporal interaction between carbon intensity and ecosystem services. The "Land" carbon intensity and ecosystem services shifted from decoupling to negative decoupling， while the "Demographic-Economic" carbon intensity and ecosystem services returned to an ideal decoupling state after undergoing negative decoupling. 3）At present，the largest proportion（47.4%）of interactive zones fell under the one-dimensional non-ideal category for "Land" carbon intensity，mainly concentrated in Nanchang and Jiujiang cities. The proportions of three-dimensional and two-dimensional ideal interactive zones increased slightly，accounting for 15.8% and 2.6% respectively，with recessive decoupling being the dominant ideal interactive relationship.［Conclusion］The findings reveal the spatio-temporal interactions between carbon intensity and ecosystem services in the Poyang Lake Eco-Economic Zone，clarify key issues in the coordinated development of economy and ecology，and provide a scientific foundation for the formulation of regional economic development and ecological conservation policies.

Abstract:［Objective］The objective of this study was to investigate the transpiration responses of Populus simonii with different degradation degrees to meteorological factors in the Bashang area.［Methods］Populus simonii with different degradation degrees in Zhangbei County，Bashang area were taken as the research object. The sap flow of P. simonii with different degradation degrees（no degradation，light degradation，moderate degradation，and severe degradation）was monitored by the thermal dissipation sap flow probe. Meteorological factors such as photosynthetically active radiation，precipitation，wind speed，air temperature，vapor pressure deficit and relative humidity were simultaneously monitored. The transpiration characteristics of P. simonii with different degradation degrees and their relationship with meteorological factors were studied.［Results］1）The transpiration rate of P. simonii with different degradation degrees during the growing season showed a unimodal trend，peaking during the day and decreasing at night. The initiation time of transpiration of undegraded and lightly degraded P. simonii was earlier than that of moderately and severely degraded P. simonii，and the peak transpiration rate of undegraded P. simonii was significantly higher than that of the other three degrees of degraded P. simonii. 2）The daily water consumption of P. simonii with different degradation degrees during the growing season showed a seasonal trend of first increasing and then decreasing， and the daily water consumption generally followed the order of undegraded > lightly degraded > moderately degraded > severely degraded. The peak daily water consumption of undegraded P. simonii（197.19±38.99）L was 2.4，3.3，and 3.9 times that of lightly degraded（82.43±5.30）L， moderately degraded （62.06±6.79） L， and severely degraded P. simonii （51.02±7.00） L， respectively. Degradation shortened the growing season of P. simonii，with the growing season of moderately and severely degraded P. simonii lasting from May to September. 3）The transpiration rate and daily water consumption of P. simonii with different degradation degrees during the growing season was extremely significantly correlated with photosynthetically active radiation，wind speed，air temperature，vapor pressure deficit and relative humidity. The daily water consumption of undegraded and lightly degraded P. simonii during the growing season showed a significant negative correlation with precipitation. There were differences in the responses of transpiration rate and daily water consumption to meteorological factors among P. simonii with different degradation degrees，and multiple meteorological factors jointly controlled the transpiration rate and daily water consumption of P. simonii. ［Conclusion］The results can provide a theoretical basis for estimating the ecological water demand and selecting appropriate stand density of P. simonii plantations in the Bashang area under balanced water conditions.

Abstract:［Objective］Accurate assessment of the value，distribution characteristics，composition and influencing factors of regional forest carbon storage and sequestration is an important basis for scientific formulation of forest management and corresponding regulation policies.［Methods］Ecotype counties belonging to typical subtropical forest areas were selected as the study area. A total of 97 sample plots with different tree species and age groups were selected to carry out field measurement of above-ground and below-ground carbon storage and sequestration， analyze the composition of carbon storage and the relationship between carbon storage and site factors，and compare the measured carbon sequestration values with those calculated by the CASA model. The aim was to provide a reference for the assessment of carbon storage and sequestration in typical subtropical forests.［Results］1）In 2020， the average forest carbon density，total carbon storage，and total carbon sequestration of vegetation layer in the study area were 158.05 t/hm²，4.07 ×10⁷ t and 28.41×10⁵ t/a，respectively. Betula forests had the highest forest carbon density，Hardwood forests and other evergreen broadleaf forests had the highest forest carbon storage and vegetation carbon sequestration. Among age groups，young forests had the highest carbon storage. The overall distribution of carbon density was ranked in the order of soil layer（56.19%）>vegetation layer（42.94%）>litter layer（0.87%）. 2）Among the site factors，soil thickness was significantly positively correlated with soil carbon density and negatively correlated with litter density. 3）Except for shrublands，the CASA model significantly underestimated carbon sequestration compared to the measured values from the sample plots，with the measured values being 96.49% higher than the model estimates.［Conclusion］In typical subtropical forests，Betula has a significant advantage in vegetation carbon density. Soil layer carbon storage is the largest part of forest carbon storage，and soil layer thickness is the most important driving factor affecting soil carbon density and litter carbon density. Additionally，except for shrublands，the model calculations underestimated the forest carbon sequestration in the study area.

Abstract:［Objective］The Zedang wide valley basin of the Yarlung Zangbo River is one of the regions where desertified land is difficult to manage. The key to address this issue is to establish a scientific model of desertification prevention and control.［Methods］ Remote sensing images were used to identify the spatial distribution and temporal evolution characteristics of desertified land. The geographical detector was employed to assess the factors influencing desertification，propose management zoning and modes，and establish priorities for future management areas.［Results］1）Desertified land was mainly distributed along both banks of the Yarlung Zangbo River，with desertification on the north bank being significantly more severe than that on the south bank. In 2020， the desertified area was 407.20 km²， a decrease of 47.13 km² compared to 2000， indicating that desertification prevention and control had achieved certain effectiveness. 2）The main factors influencing land desertification were annual average wind speed，annual average temperature，annual evaporation，and altitude， and socio-economic factors had a relatively great impact on local desertification. 3）Based on factors such as altitude，slope，and human activity，the Zedang wide valley basin was divided into eight management zones， including fixed and semi-fixed sandy lands on gentle slopes at mid-low elevations，mobile sandy land，and mountain sandy land near the airport. Eight management modes were proposed，including windbreak and sand-fixation forests，artificial enclosure and restoration，and sand industry development. The region was designated into priority management areas，key management areas，and secondary management areas.［Conclusion］The findings of this research can provide valuable insights for desertification prevention and control in the Zedang wide valley basin of the Yarlung Zangbo River in the future.

Abstract:［Objective］This study aimed to better enhance our understanding of soil enzyme activity characteristics and microbial nutrient limitations within estuarine wetland ecosystems.［Methods］Four representative habitats in the Minjiang Estuarine Wetland，including salt marshes（Phragmites australis marsh，Cyperus malaccensis marsh），bare mudflats，mangrove wetlands，and restored ponds，were selected for investigation. Variations in soil extracellular enzyme activities and enzymatic stoichiometric characteristics across these habitats were explored. ［Results］1）The activities of soil β-1，4-glucosidase（βG），cellobiohydrolase（CBH），and β-1，4-N-acetyl-glucosaminidase（NAG）were significantly higher in P. australis marshes，C. malaccensis marshes，and mangrove wetlands than in bare mudflats and restored ponds（p<0.05）. Soil enzyme activities in all habitats decreased with increasing soil depth and stabilized below 50 cm. 2）The vector angle（VA）of soil enzymes across different habitats remained consistently<45° ，suggesting that soil microbes in this area might be primarily nitrogen （N）-limited. Compared to the unvegetated bare mudflats and restored ponds，enzyme vector lengths（VL）were longer in P. australis and C. malaccensis marshes as well as mangrove wetlands，indicating stronger carbon（C） limitations in these habitats. 3）Redundancy analysis revealed that the activities of surface（0-40 cm）soil enzymes were mainly regulated by soil organic matter content，temperature，electrical conductivity，and pH， while the enzyme activities at deeper soil layers（40-100 cm）were more influenced by soil bulk density and ammonium-nitrogen content.［Conclusion］ Soil enzyme activities in the Minjiang Estuarine Wetland differ significantly across habitats and soil depths，with distinct regulatory factors influencing surface and subsurface enzyme activities. Overall，soil microbes in the region are subject to dual limitations of N and C. These findings contribute to a deeper understanding of the complex soil microenvironment in estuarine wetlands and provide valuable data for ecological protection and restoration of these areas.

Abstract:［Objective］This study aimed to study the effects of different tillage practices on the growth and development of soybean root system，the rate of root secretion，and soil physicochemical properties in the black soil region of Songnen Plain，and to clarify the differential transmission processes by which tillage practices influence crop yield through changing soil physicochemical properties and root characteristics.［Methods］A soybean variety from the northeast black soil region was used as the test materials. Four tillage treatments， including no-tillage straw mulch（NTS），no-tillage（NT），deep tillage（DT）and conventional tillage（CK）， were set. Their effects on soil physicochemical properties，soybean root morphology，and crop yield were studied. ［Results］1）NTS and DT increased soil nitrogen and phosphorus levels by exogenous straw incorporation. Compared with CK，inorganic nitrogen and available phosphorus were increased by 35.8% and 26.3% under NTS，and by 42.1% and 33.7% under DT，respectively. 2） Soil nutrient level and compactness jointly determined soybean root morphological characteristics. The direct influence of soil compactness on root morphology（path coefficient was 0.89）was greater than that of soil nutrient（path coefficient was 0.86）. Compared with CK，NTS promoted the growth and development of soybean roots under high nutrient availability and high soil compactness，NT inhibited the growth and development of soybean roots under low nutrient availability and high soil compactness，while DT promoted the growth and development of soybean roots under high nutrient availability and low soil compactness. 3）Without fertilizer application，the rate of root secretion was significantly positively correlated with root length and surface area，but significantly negatively correlated with soil nutrient concentration. 4）The explanation effect of tillage practice on soybean quality was 81%. Compared with CK，the yields under NTS，NT and DT increased by 24.7%，14.8% and 36.2%，respectively.［Conclusion］ NTS can ensure yield while reducing tillage，improving soil resistance，and promoting the recovery and retention of soil available nutrients.

Abstract:［Objective］This study aimed to investigate the effects of water-fertilizer management and greenhouse intercropping on soil microecology and the quality of cucumber and celery.［Methods］ A three-year field experiment was conducted. Two water-fertilizer modes，including continuous fertilization in irrigation（CF）and alternating fertilization in irrigation （AF），were employed. There were three planting patterns，including cucumber monoculture（CU），celery monoculture（CE），and cucumber-celery intercropping（CC）. The impacts of different treatments on crop quality， soil physicochemical properties， and microbial communities were systematically evaluated.［Results］The CCCF treatment significantly enhanced the vitamin C content in both cucumber and celery（16.6%-200%），while the CUCF treatment exhibited advantages in soluble sugar accumulation. XGB model analysis revealed that available potassium and pH were the key factors regulating vitamin C and soluble sugar content，respectively. Microbiome analysis indicated that intercropping treatments enriched specific ASVs（7 371-7 526）and significantly increased the abundance of plant growth-promoting bacteria，including Steroidobacter and Flavobacterium，while inhibiting pathogenic fungal growth. Functional prediction showed that water-fertilizer management primarily influenced nitrogen cycling functions，whereas intercropping enhanced methanotrophy functions. Microbial co-occurrence network analysis further revealed that CF formed tight bacterial networks，AF increased network modularity，and CC maintained high connectivity while preserving moderate modularity.［Conclusion］Different water-fertilizer and planting management practices differentially influenced crop quality through the regulation of soil physicochemical properties， microbial community structure，and ecological networks. Specifically，CCCF and CUCF were suitable for enhancing vitamin C and soluble sugar content，respectively，providing new insights for precise quality regulation in protected agriculture.

Abstract:［Objective］From the perspective of soil phosphorus（P）bioavailability in dryland soils，this study evaluated the effects of different P application rates and methods on soil P bioavailability and winter wheat P uptake and utilization ，aiming to provide a theoretical basis for optimizing P fertilization modes to enhance yield and P-use efficiency on the Loess Plateau.［Methods］Using the wheat variety "Changhan 58" as the test material， a two-factor experiment was implemented. The experiment included three P（P₂O₅）application rates，0（P0），60 （P60）and 120 kg/hm²（P120），and two application methods，broadcast application（S）and strip application （T）. The study investigated the effects of P application rate and method on soil P fractions，winter wheat yield， biomass，P uptake，and P-use efficiency. The impact of changes in soil P bioavailability on yield formation and P-fertilizer efficiency was analyzed.［Results］Under both application methods，winter wheat yield，biomass，and P uptake significantly increased with increasing P application rate. Under the broadcast method，the P120 treatment significantly increased the yield，biomass，and P uptake by 22.69%，29.57% and 157.06%，respectively， compared to P0；these increases were 15.56%，14.92% and 31.84%，respectively，compared to the P60 treatment. Similarly，under the strip application method，P120 significantly increased the yield，biomass，and P uptake by 38.77%，43.57% and 133.54%，respectively，compared to P0；these increases were 17.98%，23.67% and 34.26%，respectively，compared to P60. At different P application rates，strip application improved the yield， P-fertilizer partial productivity and agronomic efficiency，compared to the broadcast application method；under P120， these increases were 13.11%， 13.24% and 128.71%， respectively， with significant differences. Phosphorus application significantly increased soil total P（TP），available P（AP），hydrochloric acid-extractable P（HCl-P），enzyme-extractable P（Enzyme-P），calcium chloride-extractable P（CaCl₂-P），and microbial biomass P（MBP）contents；compared to the broadcast application，the strip application significantly increased Enzyme-P and MBP contents，which were the highest under P120. The distribution of AP in the soil under strip application better matched the root growth pattern of winter wheat. Correlation analysis revealed that winter wheat yield was significantly positively correlated with AP and strongly positively correlated with TP，MBP，HCl-P， and Enzyme-P.［Conclusion］Phosphorus fertilization significantly increases soil P content and availability. Strip application improves the distribution of available P，facilitating nutrient uptake by winter wheat and increasing yield，P uptake，and P-use efficiency. The application of 120 kg/hm² via strip application is a more effective mode for achieving high yield and agronomic P efficiency.

Abstract:［Objective］The aim of this study was to explore the possibility of extracting surface microtopographic features on crop-covered slopes， and realize three-dimensional modeling and dynamic monitoring of microtopography under crop-covered conditions.［Methods］Using the SfM-MVS（Structure from motion with multi-view stereo）method，the maize-covered slope was used as the research object，and the bare slope was used as the control. Based on the markers of bare slope and simulated microtopography，the extraction and accuracy evaluation of surface microtopography under maize-covered conditions were carried out.［Results］1）The errors of the control points on the maize-covered slope were less than 0.002 m，and the number of sparse point clouds and dense point clouds were 2.1 and 2.6 times that of the bare slope，respectively. 2）The results based on C2C（Cloud to Cloud）showed that 85.12% of the distances between maize-covered slope and bare slope point clouds were less than 0.001 m. The results of DOD（DEM of Difference）method showed that 96.07% of the height differences between maize-covered slope and bare slope DEM were less than 0.003 m，and the overall accuracy reached millimeter level. 3）The microtopographic extraction of bare slope markers were closer to the actual values，and the accuracy of length，width，and depth of markers in all directions was above 98%. Although the accuracy of the lateral markers on the maize-covered slope decreased due to the superposition of vegetation，the accuracy was still above 97%.［Conclusion］The measurement method based on SfM-MVS can be used as a high-accuracy measurement method to extract the microtopographic fluctuation characteristics of maize-covered slopes.

Abstract:［Objective］Slope vegetation is susceptible to different degrees of collapse under the action of external forces such as water flushing and wind. The aim of the study was to investigate the influence of vegetation collapse angle on the dynamic characteristics of thin-layer flow and erosion and scouring process on slopes.［Methods］Acrylic cylinders were used to simulate the stems of the plants，and an indoor flume scouring test was carried out to set up six groups of collapse angles（45°，75°，90°，105°，135°，150°）and three sets of flow conditions（0.23，0.52，0.76 L/s），and a high-frequency Particle Image Velocimetry（PIV）system was used to capture and map the flow field，so as to analyze the effects of different stem lodging angles on the characteristics of the flow field，turbulence characteristics and vortex structural features.［Results］1）The presence of stalks caused the flow velocity at the symmetry plane of the upstream of the stems to change，forming negative flow zones along the upstream of the bed and downstream of the stalks in the near-bed region（x/D=-0.1 to x/D=-0.4，y/D=0 to y/D=0.4），and both forward and backward tilting of the stems weakened the negative flow of the water. 2）The turbulence intensity of the vertical flow increased and then decreased with increasing water depth，and the locations where the maximum turbulence intensity occurred were all located near y/D=0.2，indicating that the vortex microstructure played a strong role in this region. 3）The presence of stems led to the generation of Horseshoe Vortex（HV）structures at the upstream symmetry plane. Due to the weakening effect of the forward and backward tilting of the stems on the descending flow，the HV system became obvious with the increase of the tilting angle，the vortex volume increased and gradually approached to the column，and the strength of the HV system decreased with the continued tilting of the column after it reaches 90°. The change pattern of the vortex volume with the column tilting angle of HV1 showed a parabolic pattern of increasing first and then decreasing. The maximum value of vortex was 90° > 105° > 75° > 135° > 45° > 150° .［Conclusion］The synthesis shows that，in the early stage of slope current development，tilting the plant stems can weaken the reverse flow of water at the bottom of the stems to a certain extent，inhibit the generation of downward flow，weaken the structure of horseshoe vortex，and then reduce the erosion of the bed by thin-layer flow，and the greater the degree of tilting of the stems，the better the inhibition effect on soil erosion.

Abstract:［Objective］Post-fire debris flow is a specific type of debris flow with universal common characteristics， originating from large forest fires. It is found that there is a "roasted pigskin effect" in post-fire debris flows，which is primarily attributed to the fire-calcined effect of wildfires on the underlying surface vegetation and rock-soil media.［Methods］Numerical simulation was used to analyze the fire-calcination effect on the underlying surface and reveal the temperature conduction process and changes of temperature stress on the underlying surface following the wildfire disaster.［Results］The depth of influence of wildfire on the underlying surface could reach 3 m，and the temperature stress could reach 405 MPa，which could easily cause thermal cracking and decomposition of the underlying rock and soil . The concept of the post-fire material sources was proposed，and a structure model of the post-fire material sources was established，which included two parts，namely，the volcanic ash layer and the fire-calcined layer，with the former being the primary source of the initial stage of post-fire debris flow，and the latter being the primary source of the mid-and late-stage of the post-fire debris flow. Based on the post-fire material sources，the mechanism of post-fire debris flow formation was explored，i.e.，the stage of surface-washing evolution for ash material sources and the stage of gully erosion evolution for the fire-calcined layer，the former appeared in about two years after the wildfire，while the latter spanned a much longer time scale，potentially reaching millennium to ten thousand years. From the perspective of "roasted pigskin effect" of post-fire debris flow，strategies for prevention and control of post-fire debris flow were explored.［Conclusion］The research results have positive significance for studying the formation mechanism and targeted management of post-fire debris flow.

Abstract:［Objective］Contour Reverse-Slope Terraces（CRT）are ecological engineering measures designed to mitigate soil and water loss on sloping farmland. This study aimed to explore and evaluate the improvement effects of CRT on the quality of red soil on slopes，and to provide a reference for selecting suitable soil and water conservation measures and improving soil quality in sloping farmland in the region.［Methods］Using sloping farmland in the Yizhe watershed Songhua dam in Yunnan as the study area，16 soil indicators were measured to analyze the differences in soil physical，chemical，and biological properties between control（CK）and CRT-treated sloping farmland. A minimum data set（MDS）was established to evaluate soil quality.［Results］1）In sloping farmland with CRT measures，the soil water content，geometric mean diameter，and total aggregates increased by 79.30%，11.36% and 11.43%（p<0.05），while soil bulk density decreased by 15.09% compare to those in sloping farmland of CK（p<0.05），respectively. 2）In sloping farmland with CRT measures，the soil total nitrogen，nitrate-nitrogen，total phosphorus，and total organic carbon contents increased by 33.34%， 112.58%，25.86% and 66.14%（p<0.05）compare to those in sloping farmland of CK，respectively，indicating effective nutrient retention by CRT. 3）In sloping farmland with CRT measures，total glomalin（T-GRSP）， easily extractable glomalin（EE-GRSP），leucine aminopeptidase（S-LAP），and β-1，4-N-acetylglucosidase . （S-NAG）increased by 17.45%，111.11%，92.57% and 307.36% compare to those in sloping farmland of CK （p<0.05）. 4）Three indicators，including high easily oxidizable carbon（H-EOC），S-NAG，and EE-GRSP， were identified as the main indicators for soil quality evaluation in the minimum data set. The verification of total data set suggested that the minimum data set reflected the effective information and accuracy evaluation for soil quality.（5）Overall soil quality l was ranked as CRT>CK，with the soil quality index of CRT sloping farmland increasing by 146.28%-266.34%（p<0.05），compared to that of CK.［Conclusion］CRT measures make the soil quality of sloping farmland below the terrace better than that above the terrace，elevating the soil quality below the terrace from a relatively low level to a high level. In conclusion，the implementation of CRT measures significantly improves the soil quality and productivity of sloping farmland.

Abstract:［Objective］This study aimed to investigate the response of water quality to land use and landscape patterns at different scales during the flood and non-flood seasons in the Taihu Basin.［Methods］Based on water quality data from 31 monitoring sites in the Jiangsu section of the Taihu basin from 2020 to 2023 and land use data in 2020，six water quality and pollution indicators were selected，including potassium permanganate，dissolved oxygen，ammonia nitrogen，total phosphorus，total nitrogen，and turbidity. Then land use and landscape pattern characteristics within multi-scale circular buffer zones（100，300，500，1 000，1 500 and 2 000 m）were extracted. Finally，redundancy analysis was employed to determine the optimal spatial scale and key influencing factors that explain water quality during the flood and non-flood seasons.［Results］Water quality was generally better during the flood season than during the non-flood season. However，dissolved oxygen levels were significantly higher in the non-flood season than in the flood season（p<0.05）. The spatial distribution of water quality within the study area revealed relatively good water quality in and around Taihu Lake，while water quality was relatively poor in the eastern and southern regions. This spatial variation in water quality was likely associated with the region's uneven economic development，which was characterized by "higher in the south and lower in the north，stronger in the east and weaker in the west". The 300-m buffer zone explained the strongest relationship between landscape metrics and water quality during both the flood and non-flood seasons，with the explanation rate for the flood season reaching 55.9%. The aggregation index of construction land，the percentage and division of farmland at the class level，along with Shannon's diversity index and edge density at the landscape level，were the principal factors influencing water quality in the Jiangsu section of the Taihu basin. Within the optimal 300-m buffer zone，the mean patch area，the aggregation index of construction land，and the percentage of farmland were negatively correlated with water quality and pollution indicators，including potassium permanganate，total nitrogen，total phosphorus， and turbidity. This suggests that more fragmented landscape，more dispersed patches of construction land，and the absence of dominant farmland patches，are associated with the deterioration of water quality.［Conclusion］The findings of this research provide theoretical support for the scientific formulation of land use planning and landscape pattern optimization strategies，thereby enhancing the scientific basis and precision of water quality management. In particular， the implementation of dynamic regulatory measures under varying seasonal conditions can significantly improve water quality.

Abstract:［Objective］To exploring the spatio-temporal changes of long time series in habitat quality of the Wujiang River Basin in Guizhou Province，in order to provide a theoretical reference for high-quality green development of the region.［Methods］Based on four periods of land use data from 1990，2000，2010 and 2020， the landscape pattern and habitat quality of the Wujiang River basin in Guizhou Province were calculated and the driving factors were analyzed，by using the moving window method，InVEST model，and geographic detector. ［Results］1）From 1990 to 2020，the fragmentation and patch shape complexity of the landscape pattern increased within 30 km of the main stream in the south of the upstream，while the patch dominance and landscape connectivity decreased. The fragmentation and patch shape complexity of the landscape decreased at a distance of 30-60 km from the main stream in the south of the midstream，while the landscape connectivity increased. 2）The annual mean value of habitat quality was 0.67，with an increase of 1.67% in high habitats，0.17% and 1.46% in medium low and low habitats，respectively. The proportion of high habitats in the upstream and medium low and low habitats in the midstream increased the most. The proportion of high habitats at the distance of less than 30 km from the main stream and medium low and low habitats at the distance of 30-60 km increased the most. 3）Land use intensity was the main driving factor for spatial heterogeneity of habitat quality，while temperature and rainfall were secondary factors.［Conclusion］The overall habitat quality of Wujiang River basin in Guizhou Province is medium high，and the changes in some areas are due to the trade-off between ecological protection and economic development.

Abstract:［Objective］Exploring the evolution of spatio-temporal patterns of land use benefits and its coupling and coordination relationship is crucial for the balanced allocation of resources and the transformation of land use mode. It is of great significance to achieve high-quality improvement of land use benefits and accelerating the development of new-quality productive forces in Anhui Province.［Methods］Panel data of 16 prefectural-level cities in Anhui Province from 2011 to 2020 were selected，and the entropy method and TOPSIS model were integrated to complete the measurement of land use benefits of each prefectural-level city，to analyze the spatial differentiation characteristics of the comprehensive benefits and the changes of the sub-system benefits. The spatio-temporal pattern and evolution trend of land use benefits，as well as the coupled and coordinated development level of sub-system benefits were analyzed empirically using the spatial autocorrelation and coupled coordination model. ［Results］1）From 2011 to 2020，the comprehensive land use benefits in Anhui Province showed a spatial pattern of "high in the south-low in the north，high in the center-low at the edge". The economic and social benefits were enhanced by different magnitudes with prominent regional differences，and the ecological benefits of most areas fluctuated within a certain range. 2）Land use benefits in each prefecture-level city showed a negative spatial autocorrelation and a significant convergence of differences. 3） The spatial differences in the coupling and coordination of sub-system benefits were obvious，showing a spatial pattern with Hefei City as the center，Wuhu City and Fuyang City as the sub-centers，and the degree of coupling and coordination decreasing towards the periphery. The factors limiting the level of coupled and coordinated development in Anhui Province were mainly compound factors，and the number of prefecture-level cities affected by compound factors was as high as 14 in 2020.［Conclusion］Based on the evolution trend of spatio-temporal patterns，completing targeted allocation of land resources，achieving integrated coordination and sustainable development of social，economic and ecological benefits，and constructing the linkage and synergistic layout among regions are key to comprehensively improving the land use benefits in Anhui Province and becoming a strong province of high-quality development in the future.

Abstract:［Objective］Studying the impact of extreme climate change on vegetation in the Red River basin at different time scales is of great significance for the protection and adaptive management of watershed ecosystems in the context of climate change.［Methods］Based on NDVI data from 1982 to 2022 and daily meteorological data from 38 weather stations，16 extreme climate indices were calculated using the RClimDex model. Trend detection and partial correlation analysis were used to investigate the response characteristics of NDVI to extreme climate events at annual，seasonal，and monthly scales.［Results］1）The annual average NDVI in the Red River basin was 0.68，showing a significant upward trend at a rate of 0.035 per decade（p<0.01，R²=0.78）. Spatially，NDVI exhibited a distribution pattern of "high in the south，low in the north，and high in the west，low in the east". 2）Extreme high-temperature events increased in both frequency and intensity， while among the extreme precipitation indices，only the consecutive wet days decreased significantly at a rate of 0.42 day per decade， indicating an overall warming and drying trend in the basin. 3）The increase in extreme warm indices significantly promoted vegetation growth，while the increase in extreme cold indices had a significant inhibitory effect on vegetation. The diurnal temperature range（DTR）showed a positive correlation with NDVI at a short-term scale and a negative inhibiting effect on NDVI at a long-term scale. Most extreme precipitation indices were significantly positively correlated with NDVI at the annual scale，while they mostly exhibited negative correlations at the seasonal and monthly scales.［Conclusion］There are significant differences in the response of vegetation NDVI to extreme climate indices across different time scales. Overall，temperature plays a dominant role in the dynamic changes of vegetation，with extreme temperature contributing more significantly to NDVI changes than extreme precipitation，while vegetation exhibits good adaptability to extreme precipitation events.