[Objective]This study aims to scientifically delineate land use functional zones in Anhui Province,identify the key driving factors of landscape ecological risk,and reveal the spatiotemporal evolution characteristics and spatial conflict patterns of ecological risk,providing scientific support for regional ecological security and territorial space planning.[Methods]Taking Anhui Province as the study area,a land use functional zoning scheme was developed by integrating the morphological spatial pattern analysis(MSPA),Conefor,and minimum cumulative resistance(MCR)models and applying the resistance threshold method.On this basis,This study combines the XGBoost model with the SHAP interpretation method to quantitatively analyze the effects of topographic conditions,climatic factors,and socio-economic factors on landscape ecological risks.[Results]1)According to land use functions,Anhui Province can be divided into three core areas,among which the ecological protection core area accounts for 30.96%,the agricultural production core area accounts for 35.52%,and the construction and development core area accounts for 33.52%.Spatially,the three areas are respectively concentrated in the southern Anhui region,the northern Anhui region,and the urban agglomeration in central Anhui.2)From 2000 to 2020,the overall landscape ecological risk in the region has been continuously intensifying,with the proportion of areas with high and very high risks increasing from 16.95%to 32.81%.In terms of spatial distribution,low-risk zones largely coincided with ecological protection zones,while high-risk zones were concentrated in construction development zones.3)The analysis of influencing factors showed that topographic factors exerted the greatest influence on the provincial risk pattern.Climatic factors were the dominant factors in ecological protection and construction development zones,whereas socio-economic factors had the most significant influence on risk in agricultural production zones.4)Ecological risk conflicts within the province were significant,with relatively high-and high-conflict zones accounting for 30.78%,mainly distributed in cities such as Anqing and Hefei.[Conclusion]Landscape ecological risk in Anhui Province shows an intensifying trend.The province is influenced by topographic factors,while different zones are driven by climatic and socio-economic factors,and high-risk zones are concentrated in construction development core zones.It is recommended to implement differentiated management strategies based on functional zoning,focusing on mitigating spatial conflicts in areas such as Anqing and Hefei to improve regional ecological security.The findings provide a scientific basis for the synergistic governance of territorial space planning and ecological risk.
[Objective]This study aims to reveal the spatiotemporal differentiation patterns of cultivated land landscape from the provincial scale to economic zones in Sichuan Province,and to quantify the contributions and interactive effects of natural and socio-economic factors on landscape pattern changes.[Methods]Based on multi-source remote sensing and geographic information system(GIS)technology,a spatiotemporal evolution model of landscape ecology was constructed on the ArcGIS and Fragstats platforms.Combined with the geodetector and entropy weight-TOPSIS method,the spatial heterogeneity characteristics and driving mechanisms of cultivated land landscape patterns in Sichuan Province and its five major economic zones from 2000 to 2022 were systematically analyzed.[Results]1)From 2000 to 2022,the cultivated land in Sichuan Province generally showed a trend of scale reduction,fragmentation intensification,and connectivity decline.The area of dryland decreased by 13 961.0 km²,with a higher reduction rate than that of paddy fields.The number of patches increased sharply,and landscape dominance continued to weaken.2)The five major economic zones exhibited significant differences.The Chengdu Plain Economic Zone showed quantity reduction and shape fragmentation.The Western Sichuan Economic Zone presented paddy field expansion and dryland shrinkage.Both paddy fields and dryland in the Northeast Sichuan Economic Zone decreased by more than 19%.The area of dryland in the Southern Sichuan Economic Zone decreased by 11.58%,with local retention of core cultivated areas.The area of dryland in the Panxi Economic Zone decreased by 27.49%,with the highest degree of fragmentation.3)In terms of driving mechanisms,the interactions between natural and socio-economic factors were dominated by two-factor enhancement and nonlinear enhancement effects.Among them,population density had the highest interactive explanatory power(0.97).The influence of human-driven factors generally increased across regions.Economically developed areas were mainly driven by urbanization and industrialization,ecologically sensitive areas were dominated by natural constraints and policy regulation,and traditional agricultural areas were trapped in a cycle of agricultural decline and population loss.[Conclusion]The findings of this study can provide a theoretical basis for the construction of an ecological security pattern for cultivated land and differentiated management strategies in Sichuan Province,thereby supporting the sustainable use of cultivated land landscapes and the process of territorial spatial governance.
[Objective]This study aims to investigate the morphological change process of scour holes at the headcut of ephemeral gullies on slopes with typical herbaceous communities and their main controlling factors.[Methods]Field runoff scouring experiments were conducted on slopes covered by three typical herbaceous communities in the loess hilly-gully region(Stipa bungeana,Lespedeza davurica,and Artemisia gmelinii).Close-range photogrammetry was applied to monitor morphological change processes of scour holes.[Results]1)Significant differences in root mass density and soil properties were observed among different herbaceous communities.In the topsoil layer(0～0.2 m),the Artemisia gmelinii community exhibited significantly higher root mass density,root length density,total porosity,saturated water content,and aggregate mean weight diameter than the other two communities,while soil bulk density,cohesion,and penetration resistance showed the opposite pattern.2)Herbaceous communities significantly affected the morphological characteristics of scour holes and their change processes.Morphological parameters,including width,height,depth,area,volume,shape factor,and depth-to-diameter ratio,showed fluctuating variations with scouring duration,following an increase-decrease-increase trend.Significant differences in morphological development of headcut scour holes at gullies were observed among different herbaceous communities,with the slowest development in the Artemisia gmelinii community,followed by Lespedeza davurica and Stipa bungeana.3)Pearson correlation and partial least squares(PLS)analyses showed that root mass density,root length density,total porosity,saturated water content,and aggregate mean weight diameter significantly affected scour hole depth.PLS structural equation modeling(PLS-SEM)indicated that vegetation root traits and aggregate mean weight diameter were key factors affecting scour hole depth development,with total effects of-0.65 and-0.53,respectively.Vegetation roots significantly increased soil aggregate stability,thereby inhibiting scour hole development.[Conclusion]The findings provide important theoretical support for understanding mechanisms by which vegetation restoration influences headward erosion in ephemeral gullies.
[Objective]This study systematically characterizes the spatial correlation network of new-type urbanization and examines its impact on territorial spatial utilization efficiency,aiming to provide theoretical support and references for improving new-type urbanization policies and promoting the efficient utilization of territorial space.[Methods]Based on panel data from 21 prefecture-level cities in Guangdong Province from 2005 to 2023,social network analysis was used to characterize the spatial correlation network of new-type urbanization.A super-efficiency model(SBM)was applied to measure territorial spatial utilization efficiency,and a panel data-based fixed effects model was constructed to empirically validate the impact of the spatial correlation network of new-type urbanization on territorial spatial utilization efficiency.[Results]1)The spatial correlation network of new-type urbanization in Guangdong Province formed a core-periphery stratification structure,with the Pearl River Delta as the core area and the remaining regions as peripheral areas.2)The network relevance score remained at 1 throughout the study period,and no island nodes were observed.Network density first increased and then decreased,but overall remained at a relatively low level.Network hierarchy showed a fluctuating declining trend,indicating a transition from a hierarchical structure to a flatter one.Network efficiency first increased and then gradually decreased,while network stability improved.3)The degree centrality,closeness centrality,and betweenness centrality of Guangzhou,Shenzhen,Foshan,and Zhuhai remained at relatively high levels.4)The spatial correlation network of new-type urbanization helped improve territorial spatial utilization efficiency.However,this enhancement effect was more pronounced in the Pearl River Delta region,plain areas,and in the dimension of urban spatial utilization efficiency.[Conclusion]It is necessary to internalize network-based thinking to guide the transformation of new-type urbanization and to encourage cities to formulate differentiated development strategies based on their own resource endowments and functional positions within the spatial correlation network of new-type urbanization,thereby strengthening the role of the network in promoting territorial space efficient utilization.
[Objective]This study investigates the response characteristics of water storage at gully heads to rainfall in the black soil region of Northeast China,reveals the variation patterns of water storage at gully heads before and after rainfall,and establishes a quantitative prediction method for its changes before and after rainfall.[Methods]Four gully heads with similar developmental stages and scales in three study areas(Jiusan,Binxian and Jiutai)were selected as research objects.Differences in soil hydraulic parameters,decay coefficients of water storage,and variation patterns of water storage before and after rainfall were investigated through transient water release and imbibition method(TRIM),numerical fitting,and prediction model construction.[Results]Obvious hysteresis effects were observed in soil-water characteristic curves(SWCC)of soils at gully heads,with the intensity ranking as gully 1 ≈ gully 2＜gully 3＜gully 4.After rainfall,water storage decayed exponentially over time,showing rapid decline in the initial stage and slower decline in the later stage.The decay coefficient(Kd)of water storage decreased progressively with increasing soil depth.Model simulations showed that water storage changes at 85.7%of the monitoring sites were best predicted using 1 h maximum rainfall intensity(I1 h)as the rainfall input parameter,whereas 14.3%of the sites were better simulated using 2 h average maximum continuous rainfall intensity(I2 h)as input.Therefore,in predicting soil water storage changes,I1 h could be selected as the rainfall input parameter for sites with good infiltration performance,such as gully heads or severely eroded sites.However,I2 h should be selected as the rainfall input parameter for sites with poor infiltration performance or strong water redistribution.[Conclusion]The evolution of water storage at gully heads after rainfall in the black soil region of Northeast China can be effectively characterized using exponential decay patterns and short-duration rainfall indices.The constructed model can accurately and quantitatively predict short-duration water storage changes at gully heads at the event scale,which provides methodological support for prediction and early warning of gully erosion processes.
[Objective]This study aims to examine whether and how conservation tillage improves the climate adaptability of grain production,revealing its heterogeneous effects from a dual-dimensional perspective of proactive response and passive adaptation.[Methods]Based on panel data from 44 sample counties in Heilongjiang Province,China,from 2012 to 2022,a dual-dimensional evaluation framework was established incorporating proactive response and passive adaptation.The Tobit models,system generalized method of moments(GMM),double machine learning,and spatial Durbin models were employed to empirically test the impacts of conservation tillage on climate adaptability.[Results]1)From 2012 to 2022,the climate adaptability of grain production in Heilongjiang Province exhibited an overall evolution pattern of first declining and then rising,with 2017 as a key turning point.Spatially,the pattern evolved from a scattered distribution of high-value areas in the early stage to a distinct east-west differentiation,with high-value areas in the east and low-value areas in the west.2)Conservation tillage had a significantly positive effect on proactive response,but no significant effect on passive adaptation.The system GMM results showed that the first-order lag term of climate adaptability was significantly positive,indicating that the adaptability improvement showed evident path dependence and dynamic accumulation characteristics.Spatial analysis further demonstrated that the direct and indirect effects of conservation tillage on proactive response were 0.119 and 0.711,respectively,with indirect effect playing a dominant role,indicating a significant spatial spillover effect.3)The effect of conservation tillage on improving proactive response was more pronounced in regions with higher levels of economic development and flatter terrain.[Conclusion]Conservation tillage can significantly improve the climate adaptability of grain production,mainly by strengthening proactive response,and exhibits evident path dependence and spatial spillover characteristics.The research findings provide a basis for optimizing agricultural climate adaptation policies from a dual-dimensional perspective and for enhancing the resilience of grain production systems.
[Objective]To investigate the differences in moisture swelling characteristics between residual soil and colluvial soil in the granite red soil Benggang area and to clarify their driving mechanisms for rill development.[Methods]Using soil ring samples and undisturbed whole-section soil box samples,the swelling displacement and swelling force of four types of soil-residual red soil,residual sandy soil,colluvial red soil,and colluvial sandy soil-were dynamically monitored during water absorption.Four degrees of dry-wet variation,ranging from saturated to air-dried,were established.The disintegration rate was quantified using a static water disintegration test,and rill development morphology and soil loss characteristics were tracked through runoff scouring tests.[Results]1)The moisture swelling stress of the residual soil(residual red soil and residual sandy soil)was higher,reaching 5.9,and 4.6 kPa,respectively,with stable swelling displacements of 1.0,and 0.3 mm.The swelling stress of colluvial soil(colluvial red soil and colluvial sandy soil)was only 2.5,and 0.1 kPa,with stable swelling displacements of 0.5,and 0.2 mm.2)The residual soil did not completely disintegrate,but its disintegration rate significantly increased with an increasing degree of initial dry-wet variation.In contrast,the colluvial soil was not affected by dry-wet variation and completely disintegrated within a short period.3)Rill development in the residual soil was strongly dependent on dry-wet variation.There was almost no rill development without dry-wet variation,and the rill size increased with an increasing degree of dry-wet variation.Under an extremely high degree of dry-wet variation,the rill depths for the residual red soil and residual sandy soil were 2.2,and 5.3 cm,respectively.Rill development in the colluvial red soil and colluvial sandy soil was not affected by the degree of dry-wet variation,with maximum rill depths exceeding 6,and 8 cm,respectively.4)The rill in the residual soil underwent only one minor development during the initial scouring stage and then stopped expanding.In contrast,the rills in the colluvial soil exhibited continuous and fluctuating development with increasing scour time.[Conclusion]The original mosaic structure of granite residual soil has strong resistance to scouring,but the moisture swelling damages its thin surface layer,serving as the trigger for minor rill development.Colluvial soil,due to its inherent characteristics,is more prone to disintegration and continuous rill development.The findings of this study provide a theoretical basis for the prevention and control of erosion in granite red soil.
[Objective]Shallow landslides caused by heavy rainfall occur frequently in the mountainous areas of China,particularly in areas with vegetation cover,posing a serious threat to the safety of public infrastructure and human activities.However,the mechanisms by which root structure and transpiration affect slope instability are still not fully understood,and the synergistic effects between root instability characteristics,seepage characteristics,and soil pressure parameters during rainfall remain unclear.[Methods]To address the unclear mechanisms of tree species with plank roots on slopes in Malipo County,Yunnan Province,this study employed a rainfall centrifuge model test system to simulate the instability and failure process of a slope with plank roots subjected to five intermittent rainfall events.The instability evolution characteristics of the slope with plank roots were analyzed,and the impact of transpiration on water migration paths within the slope was investigated.By establishing relationships between water content,soil pressure,and instability characteristic parameters within the slope,the instability evolution mechanisms of the slope with plank roots were revealed.[Results]After five intermittent rainfall events,more than 90％of the slope surface with plank roots collapsed,and the maximum failure depth reached 2.89 times the plank root depth.Only a local area on the left side of the slope surface retained its original morphology.During the rainfall infiltration process,transpiration led to the formation of a low-water-content zone centered on the root system on the surface of the slope with plank roots.The shape of this zone evolved gradually from a"cup-shaped"pattern to"semi-elliptical"and"triangular"patterns as the rainfall stages progressed.After the five rainfall events,the low-water-content zone on the slope completely disappeared.Meanwhile,changes in soil pressure were primarily affected by changes in the volumetric water content of the overlying soil.When the soil on the slope surface experienced a dynamic fluctuation characterized by first increasing and then decreasing,the soil pressure exhibited a phased"increase-decrease-increase"pattern in response to the changes in water content within the slope.[Conclusion]The findings of this study can provide valuable references for the design and implementation of ecological slope protection projects with plank roots in mountainous areas.
[Objective]As a high water-consuming industry,agriculture relies on the coordination of blue and green water for crop water use.Future climate change will disturb the blue and green water cycles by affecting crop water requirements(ETc)and threaten agricultural water security.Therefore,in the face of severe challenges for sustainable water resource management,predicting agricultural water security is of great significance.[Methods]Taking northeast China as the study area,based on the CMFD reanalysis dataset from 1998 to 2024 and meteorological data under two emission scenarios(SSP245 and SSP585)from 2031 to 2090 derived from five climate models in CMIP6,the Hargreaves equation and crop coefficients were used to calculate ETc,and a dual-index evaluation system for blue and green water was constructed.Combined with the crop water deficit index(CWDI),the spatiotemporal evolution trends of agricultural water security in northeast China under future climate scenarios were analyzed.[Results]The spatiotemporal characteristics of agricultural green and blue water security in northeast China differed significantly under future climate scenarios.Temporally,the green water risk decreased significantly under both SSP245 and SSP585 scenarios.In the long term,the green water risk under SSP245 was 12.4％lower than that under SSP585,while the blue water risk was 4.1％higher.Spatially,under the SSP245 scenario,high-green-water-risk areas were concentrated in Liaoning Province,and blue water stress intensified significantly in Liaoning Province and the four eastern leagues of Inner Mongolia.Under the SSP585 scenario,the overall green water risk decreased,and areas with extremely high blue water stress were concentrated in Liaoning Province.Under the SSP245 scenario,the green water risk in Jilin,Liaoning,and Heilongjiang decreased by 2.2％,13.4％,and 1.6％,respectively,compared to the SSP585 scenario,while the blue water risk in the four eastern leagues of Inner Mongolia,Liaoning,and Heilongjiang increased by 13.1％,55.1％,and 15.0％respectively.The concentration of agricultural water use risk in the early growth stage under future climate scenarios was attributed to the mismatch between water supply and demand and unstable water recharge.[Conclusion]The imbalance between the supply and demand of crop green water further strengthens the compensatory demand for blue water.The uncertainty and risk of agricultural water use are higher under the high-emission scenario.The findings of this study provide scientific support for enhancing regional agricultural climate resilience and achieving food security and sustainable water resources utilization.
[Objective]This study aims to enhance the spatial estimation accuracy of soil organic carbon(SOC)and total nitrogen(TN)in the 0-30 cm soil layer in the Zhangye region and to identify the key driving factors and their directional effects.[Methods]Multi-source covariates,including climate,topography,vegetation,and soil physicochemical properties,were integrated to construct a feature set based on field sampling data(N=979).Nine types of machine learning models were systematically compared,from which XGBoost,gradient boosting regression trees(GBRT),and random forest(RF)were selected as representative tree-based models.Three ensemble strategies were adopted to establish ensemble models,including auto-weighted,blending,and bagging.Their performance was comprehensively evaluated using 10-fold cross-validation and an independent test set.SHapley Additive exPlanations(SHAP)values were applied to quantify variable contributions and their directional effect.[Results]For single models on the test set,SOC estimation yielded R2 values of 0.768,0.773,and 0.729,root mean square error(RMSE)values of 0.472,6.421,and 7.011,and mean absolute error(MAE)values of 0.314,4.319,and 4.641 for XGBoost,GBRT,and RF,respectively.For TN estimation,the single models produced R2 values of 0.636,0.645,and 0.629,RMSE values of 0.602,5.381,and 5.498,and MAE values of 0.360,3.225,and 3.265,respectively.Overall,the ensemble models outperformed the single models.The auto-weighted demonstrated the best performance(SOC:R2_test=0.887 9,RMSE=4.607 9,MAE=2.948 2;TN:R2_test=0.775 8,RMSE=4.330 8,MAE=2.418 6),followed by blending(SOC:R2-test=0.848 7,RMSE=5.107 2,MAE=2.991 9;TN:R2_test=0.734 6,RMSE=4.576 2,MAE=2.337 3).SHAP analysis revealed stable positive contributions from precipitation and vegetation indices,negative contributions from temperature factors such as minimum temperature,and prominent contributions from soil properties including cation exchange capacity(CEC)and the proportions of clay and silt.Spatially,areas with high SOC and TN values were mainly distributed in mountainous regions characterized by relatively sufficient moisture,lower temperatures,and better vegetation coverage.In contrast,low-value areas were concentrated at oasis margins and desert transition zones.[Conclusion]The integration of tree-based ensemble modeling and SHAP interpretation enables highly accurate,robust,and interpretable regional mapping of SOC and TN.This approach provides a quantitative basis for carbon and nitrogen assessment and zonal management in arid-semiarid transition zones.
