[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.
For many years, the exploration of natural gas in the large structural belts of the northern Qaidam Basin has yielded unsatisfactory results, which may be related to the traditional interpretation of deep-seated paleo-anticlinal traps based on the dual-layer structural model. Through seismic data interpretation and structural analysis, it is concluded that the dominant structural style of this area is mainly of synsedimentary compressional strike-slip structures that developed in the late Himalayan period. Strongly deformed structures occur as a ruptured anticlines with faults extending to the surface, resulting in low-abundance traps of underfilled gas accumulations. In contrast, the gentle anticline of Chahan, which developed as a synsedimentary overlying anticline over uplifted fault blocks associated with deep compressional strike-slip movement, exhibits more favorable conditions for hydrocarbon accumulation. Because deformation related with strike-slip belt is primarily concentrated along fault zones, the intervening sags generally experience relatively weak deformation, which is conducive to the preservation of gas reservoirs and therefore represents favorable targets for gas exploration as long as there is a gas source rocks. The Pingdong Sag, located between the Altun, Jianshan, and Eboliang structural belts, experienced gentle deformation during the Cenozoic and exhibits relatively complete distribution of three Mesozoic–Cenozoic tectonic layers, containing all geologic elements of a gas system. The deep-buried Jurassic source rocks within the sag are characterized by larger thickness and stable distribution and are currently in the stage of gas generation, suggesting that major gas accumulation occurred during the late Himalayan period. The fault-block structures developed in the lower Cenozoic tectonic layer provided effective migration and accumulation system. The lower Youshashan Formation (N21) delta front sandstone bodies and overlying mudstone intervals form favorable reservoir-caprock assemblages, while the lacustrine mudstones and evaporites in the upper tectonic layers (N22, N23, Q) offer an effective regional sealing conditions for gas preservation. The analysis suggests that the Chahan anticline, located above the source-rock and developed contemporaneously with major gas-generation phase, has the potential to host a large gas field. Furthermore, subtle traps beneath the regional sealing strata, including low-amplitude anticlines, fault-block traps, lithological traps on tectonic setting, and fault–sandstone combination traps within the sub-sags of the Pingdong Sag, constitute favorable exploration targets for natural gas. This study also has reference significance for natural gas exploration in regions characterized by tectonic settings similar to those of the Qaidam Basin.
[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.
[Objective]To improve the accuracy of ground point extraction from unmanned aerial vehicle structure-from-motion(UAV-SfM)point clouds,and to construct high-precision digital elevation model(DEM)for complex terrain in the hilly and gully region of the Loess Plateau.[Methods]At large spatial scales,this study utilized a spatial distribution feature-based ground extraction(SDFGE)method that considered near-ground point clouds using UAV-SfM data.It further investigated the effects of plot scale,terrain slope,vegetation coverage,and point cloud density on ground point extraction accuracy.[Results]1)The Type I error,Type II error,and total error of ground point extraction using the SDFGE algorithm were 13.68%,12.92%,and 13.40%,respectively,showing reductions of 1.16%,6.02%,and 2.79%,respectively,compared with the CSF algorithm.2)For DEM construction,the SDFGE algorithm had an average error of 0.56 m,23.29%lower than that of the CSF algorithm(0.73 m).The standard deviation was 1.57 m,13.26%lower than that of the CSF algorithm(1.81 m).3)A quantitative evaluation was conducted on the effects of plot scale,terrain slope,vegetation coverage,and point cloud density on ground point extraction.[Conclusion]The proposed SDFGE algorithm significantly improves the accuracy of ground point extraction in the hilly and gully region of the Loess Plateau by integrating the spatial distribution features of near-ground point clouds,offering a low-cost and efficient solution for obtaining high-precision DEM data for soil and water conservation monitoring.
[Objective]To investigate the characteristics of extreme climate over the past 2005-2021 years in the Daheba river basin on the northeastern margin of the Tibetan Plateau and the mechanisms through which it influences landslide development.[Methods]Based on meteorological data from the Xinghai Station from 1960 to 2021,22 extreme climate indices were calculated using the RClimDex model to analyze the variation trends of temperature and precipitation.Multi-source remote sensing images and unmanned aerial vehicle(UAV)-derived digital surface model(DSM)data were used to interpret the spatiotemporal distribution of newly formed(Type Ⅰ)and expanded(Type Ⅱ)landslides in 28 debris flow gullies from 2005 to 2021.Pearson correlation analysis revealed the driving mechanisms of climate factors on landslide development.[Results]1)From 1960 to 2021,the climate showed significant trends of warming and wetting,with increases in the frequency and intensity of extreme high-temperature events and decreases in extreme low-temperature events.Precipitation patterns shifted toward high-frequency,short-duration heavy rainfall.2)Landslide activity intensified.From 2005 to 2021,the number of landslides increased from 218 to 1 125(average annual growth rate of 10.5%),and the landslide area expanded from 6.25×10⁴ to 44.69×10⁴ m²(average annual growth rate of 12.3%).Among them,Type Ⅰlandslides accounted for 56%(average thickness of 0.65 m),and Type Ⅱ landslides accounted for 44%(average thickness of 1.35 m).Landslide development accelerated after 2016,with engineering disturbances in 2018 caused a sharp increase in landslide density along roads.3)Newly formed landslides(56%)were correlated with extreme precipitation(Rx5day,r=0.68),while expanded landslides(44%)were driven by cold night frequency(TN10p,r=0.64)and dry day count(CDD,r=-0.67).4)The loess-cobble-sand structure regulated landslide types.Shallow landslides(0.65 m thick)were caused by the low permeability of loess(1.81 m/d),while the deep landslides(1.35 m thick)were associated with the high permeability of cobble layers(3.02 m/d).[Conclusion]Extreme climate events drive landslides through direct(rainfall)and indirect(freeze-thaw)effects,and the loess-cobble-sand structure and human engineering activities further aggravate disaster risks.The results can provide a reference for predicting debris flow material sources on the northeastern margin of the Tibetan Plateau.
[Objective]To investigate the influence of the coupling effects of parent material types and water temperature on red soil disintegration.[Methods]Soils developed from shale,siltstone,argillaceous nodular limestone,argillaceous limestone,and Quaternary red clay in a subtropical hilly region were selected as research objects.Laboratory disintegration experiments were conducted on undisturbed soils to analyze the disintegration characteristics of red soils under different water temperature conditions.Combined with soil pore structure and clay mineral composition,the influence mechanisms of parent material-water temperature coupling effect on red soil disintegration were explored.[Results]Water temperature was a key environmental factor influencing red soil disintegration.Increasing water temperature from 5 to 45℃significantly enhanced red soil disintegration.The disintegration rates of soils developed from argillaceous nodular limestone and quaternary red clay increased by 13.70%and 23.20%,respectively.These changes were mainly related to processes such as increased pore gas pressure,dissolution of cementing materials,weakening of inter-particle forces,and mass transfer driven by thermal gradients.At 25℃,the resistance to disintegration of red soils from different parent materials ranked from weak to strong as Quaternary red clay
[Objective]To analyze the carbon-water coupling characteristics of typical ecosystems on the Loess Plateau and to reveal the interannual and intra-annual dynamics,spatial patterns,and differences in water use efficiency(WUE)across different ecosystem types.[Methods]By integrating multi-source remote sensing and flux data,an optimized Biome-BGC model was employed to simulate and analyze the spatiotemporal evolution characteristics of WUE in three typical ecosystems on the Loess Plateau(forest,shrubland,and grassland)from 2000 to 2018 following the implementation of the Grain for Green Program(GFGP).[Results]1)The optimized model significantly improved simulation accuracy for gross primary productivity(GPP)and evapotranspiration(ET)across all ecosystem types,with forests showing the highest accuracy(R²=0.95 for GPP;R²=0.94 for ET).Grasslands,however,exhibited relatively greater uncertainty in simulations(R²=0.73 for GPP;R²=0.67 for ET).2)During 2000-2018,GPP,ET,and WUE all increased on the Loess Plateau.Notably,WUE in forests and grasslands increased significantly(growth rates of 5.38%and 18.45%,respectively),whereas WUE in shrublands declined.Spatially,the majority(70.23%)of the Loess Plateau showed increasing WUE,but the areas with significant increases in ET were much larger than those of WUE or GPP,predominantly located in the regions with markedly enhanced vegetation cover.3)All three ecosystem types showed a double-peak and single-trough pattern of intra-annual variation in WUE,with peaks in May and October and a trough in July.During the entire growing season,both WUE and GPP across all ecosystem types followed the order:forest>shrubland>grassland.Notably,ET in shrublands approached or even exceeded that of forests during the early and late growing seasons.[Conclusion]Compared to shrublands,forests and grasslands are more suitable as the priority types for vegetation restoration on the Loess Plateau.With past vegetation restoration projects,WUE increased in forests and grasslands but declined in shrublands.These findings provide valuable insights for ecological restoration and carbon-water resource management and regulation on the Loess Plateau.
[Objective]This study aims to address the increasingly severe ecological challenges in Heilongjiang Province,including accelerated urbanization,landscape fragmentation,and biodiversity loss,thereby promoting healthy development of the ecosystem.[Methods]Based on land use data from 2000,2010,and 2020,landscape indices and landscape ecological risk indices were calculated to construct an ecological risk assessment model.The influence of ecological risk on ecological resistance was comparatively analyzed,and the ecological risk assessment results from 2020 were integrated into the comprehensive resistance surface.Ecological sources were identified and screened using the MSPA model and landscape connectivity analysis.Ecological corridors were extracted based on the minimum cumulative resistance(MCR)model and circuit theory.A multi-level ecological security pattern was constructed by integrating ecological risk zoning.[Results]1)From 2000 to 2020,the high-risk areas of landscape ecology in Heilongjiang Province showed an overall decreasing trend and exhibited a spatial distribution pattern of"high on both sides and low in the middle".2)Eleven ecological sources were identified and selected,and 24 ecological corridors with a total length of 6 443 km were established,providing a scientific basis for regional ecological protection and landscape optimization.3)A total of 85 ecological pinch points and 36 ecological barrier points were identified.Combined with territorial spatial planning and ecological risk zoning,an ecological security pattern of"dual-core leadership,three-axis linkage,four-zone coordination,and multi-point support"was proposed.4)The limitations of this study lay in the incomplete integration of ecosystem service functions and the lack of validation on the actual operational effectiveness of the ecological network.[Conclusion]The method and application of ecological security pattern construction based on ecological risk assessment proposed in this study can provide theoretical guidance and practical reference for Heilongjiang Province to promote the optimization of territorial space layout and enhance the sustainable utilization efficiency of territorial space.
[Objective]This study investigates the spatiotemporal evolution characteristics and trade-off/synergy relationships of ecosystem services in the Yanhe River basin,aiming to provide a scientific basis for targeted soil and water conservation and regional high-quality development.[Methods]Based on multi-source data,including land use data,soil data,meteorological data,and digital elevation model(DEM)data from 1980 to 2020,this study applied ArcGIS and the InVEST model to assess the spatiotemporal evolution patterns and trade-off/synergy relationships of four ecosystem services in the Yanhe River basin during this period.[Results]1)During the study period,the average annual water yield in the basin was 2.04×108 m3(with a runoff depth of 26.55 mm),showing an Ω-shaped trend,with the water yield per unit area increasing first,followed by a decline,and finally increasing again.Spatially,the water yield was generally higher in the middle reaches and lower in the upper and lower reaches.2)The total soil conservation displayed a U-shaped fluctuating increasing trend,with the highest per-unit-area values rising rapidly during 2010-2020.Spatially,high-value zones of soil conservation were scattered,following a distribution pattern of higher in the south and lower in the north.3)Carbon storage increased year by year,with high-value zones of carbon storage per unit area progressively expanding from south to north,showing a distribution pattern of higher in the south and lower in the north.4)The average habitat quality index of the basin showed a continuous decreasing trend annually,with overall low habitat quality.The habitat quality in the southern forested areas was relatively good,while low-value zones were distributed in strip patterns along river channels.5)Significant correlations(p<0.01)were observed among the four ecosystem services in the Yanhe River basin.Water yield and carbon storage,as well as water yield and habitat quality,demonstrated significant trade-off relationships.Soil conservation,carbon storage,and habitat quality demonstrated synergistic relationships with each other.The water yield-soil conservation relationship was a trade-off in 1980,then shifted to synergy,and returned to trade-off in 2010.Most regions exhibited no pronounced trade-offs or synergies.Overall,synergistic areas within the basin progressively diminished,while trade-off areas expanded.High-high synergy clusters were primarily concentrated in the mid-lower reaches,low-low synergy was mainly in the upper reaches,and trade-off relationships were predominantly scattered in the mid-upper reaches.[Conclusion]The quantitative assessment of this study reveals the spatiotemporal evolution patterns and trade-off/synergy relationships of ecosystem services in the Yanhe River basin,providing a scientific basis for enhancing the integrated benefits of ecosystem services and optimizing resource allocation on the Loess Plateau.
[Objective]To explore the soil moisture migration patterns influenced by ground fissures in coal mining subsidence areas on soil water migration and reveal their migration mechanisms,and clarify the regulatory roles of different vegetation types and soil physical and chemical properties in this process.[Methods]Typical vegetation types(Artemisia desertorum,Poa annua,and biological soil crusts)in the Caojiatan mining area were taken as the research objects.Soil infiltration rate and evaporation characteristics under different treatments were monitored using a double-ring infiltrometer and a micro-lysimeter.Combined with analyses of soil physicochemical properties(bulk density,porosity,mechanical composition,etc.),analyze the influence mechanisms of ground fissures on moisture migration were elucidated under different plant-soil system.[Results]1)Mining-induced ground fissures significantly affected soil moisture migration in surrounding areas.Their existence increased soil infiltration rate and evaporation,both of which rose significantly closer to the fissures and declined with increasing horizontal distance.2)The dynamic responses of soil moisture varies under different vegetation covers.Among them,the stable infiltration rate under A.desertorum was significantly higher than in other treatments,as its root system formed macropores that promoted the development of preferential flow.Infiltration rate and evaporation followed the order of A.desertorum>P.annua>bare land>moss crust.3)Both soil infiltration rate and evaporation showed extremely significant negative correlations with soil bulk density,but extremely significant positive correlations with total porosity and capillary porosity.Higher porosity enhanced soil water-holding capacity and hydraulic conductivity,thus promoting water infiltration and evaporation.[Conclusion]Mining-induced ground fissures significantly promote the migration process of surrounding soil moisture.This process is mainly controlled by pore structure,with total porosity and soil bulk density being the key influencing factors.The research results provide theoretical references for ecological restoration in coal mining subsidence areas.
[Objective]To explore the characteristics of soil labile organic carbon(LOC)fractions in Larix gmelinii forests with different understory vegetation types and to provide a scientific basis for studying forest soil LOC and its stability in the Daxing'an Mountains.[Methods]Four types of L.gmelinii forests with distinct understory vegetation were selected as study sites,Rhododendron dauricum-L.gmelinii forest(DJL),Ledum palustre-L.gmelinii forest(DXL),Carex tristachya-L.gmelinii forest(TCL),and Sphagnum palustre-L.gmelinii forest(TXL).From May to September of 2024,the mass fractions of soil LOC fractions in the 0-30 cm soil layer were measured,as well as the carbon and nitrogen mass fractions of litter and mattic epipedon.The mass fraction variation patterns of soil LOC fractions of L.gmelinii forests were analyzed across different understory vegetation types,and their key influencing factors were identified.[Results]1)From May to September,the overall mean mass fraction of soil microbial biomass carbon(MBC)in the 0～30 cm soil layer of TCL(612.40 mg/kg)was significantly higher than that of the other three forest types(p<0.05),with the lowest value observed in DXL(355.07 mg/kg).TXL exhibited the largest increase,whereas DXL showed the smallest.2)The mass fractions of easily oxidized organic carbon(EOC)peaked in July across all forest types.Among them,TXL consistently had higher EOC mass fractions in the 0-5,5-10,and 20-30 cm soil layers compared with TCL and DXL,and significantly higher than DJL(p<0.05).Furthermore,the variation of EOC mass fractions in TCL and TXL from May to September was greater than in DJL and DXL.3)Soil dissolved organic carbon(DOC)mass fractions of four forest types declined from May to September in a fluctuating pattern,ranging from 72.23 mg/kg to 284.36 mg/kg.The reduction in TCL was significantly greater than in DJL and DXL(p<0.05),but did not differ significantly from TXL(p>0.05).4)In July,the mass fraction of particulate organic carbon(POC)in the 0-30 cm soil layer of TCL was higher than that in other forest types,with the lowest value in DJL.The overall mean POC mass fractions in TCL and TXL were significantly higher than those in DXL and DJL(p<0.05),while differences between TCL and TXL,and between DXL and DJL,were not significant(p>0.05).5)In DJL and DXL,soil LOC fractions were significantly positively correlated with total organic carbon(TOC)and total nitrogen(TN),but negatively correlated with soil bulk density(BD)and soil ammonium nitrogen(AN)(p<0.05).BD and TOC were identified as dominant factors influencing soil LOC fractions in TCL and TXL.[Conclusion]Understory vegetation has a significant impact on the soil LOC fractions of L.gmelinii forests.The mean mass fractions of soil EOC,DOC,and POC in TCL and TXL are significantly higher than in DXL and DJL,while the soil MBC mass fraction in TCL is significantly higher than in other forest types.From May to September,the variation of soil LOC mass fractions in TCL and TXL is larger than that in DJL and DXL.The research results are of great significance for understanding soil carbon pools and their stability in L.gmelinii forests with different understory vegetation types.
Controlling film morphology remains an inherent challenge limiting the performance of all-small-molecule organic solar cells (ASM-OSCs), primarily due to excessive donor-acceptor compatibility restricting further improvements. Here, we introduce a novel strategy employing rhodanine-based film-forming kinetic modulators-specifically tailored for the high-performance donor BTR-Cl- including 3-methylrhodanine (C1), 3-ethylrhodanine (C2), 3-butylrhodanine (C4), and 3-hexylrhodanine (C6). We demonstrate that the C2 modulator uniquely optimizes morphology by extending film-formation time and fine-tuning donor-acceptor miscibility, leading to enhanced molecular ordering, uniform vertical distribution, and optimal phase separation. This synergistic morphological control significantly boosts BTR-Cl crystallinity and facilitates efficient three-dimensional charge transport networks. Consequently, C2-treated BTR-Cl:N3 ASM-OSCs achieve an outstanding power conversion efficiency (PCE) of 17.12 %, ranking among the highest reported for this system. Crucially, this work introduces a novel "donor-modulator structural matching" strategy, providing a powerful new avenue for controlling film-forming kinetics to realize high-performance ASM-OSCs. (c) 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
