Temporal And Spatial Characteristics Analysis Of Soil Conservation Function In Gannan Region Based On InVEST Model

The southern of Jiangxi province is the upper reaches of the Ganjiang River in the Poyang Lake Basin,an important part of the southern hills in China.The systematic analysis of the Time-space characteristics of soil conservation in Gannan Region is of great significance for improving the soil conservation capacity and maintaining the ecological security barrier of the southern hills.In this study,utilize the InVEST model,calculate the soil erosion capacity and soil retention capacity of different land use types,different elevations,different slopes,different counties in Gannan Region with the data observed among 2000,2010,and2018.Analyze the spatial correlation between soil conservation capacity and NDVI(normalized differential vegetation index),analyze the spatial features and temporal changes of soil conservation functions in Gannan Region.Determination of the main influencing factors of soil conservation function by geo-detector.Research shows:(1)From 2000 to 2018,With the development of the economy and the expansion of the city,cultivated land,irrigated forest land,water area,and unused land decreased trend,while urban land and rural residential land increased greatly.(2)The mean value of soil erosion capacity in the study area from 1.09×10~3t/(km~2·a)to 1.02×10~3 t/(km~2·a),the forest soil erosion area was the largest,accounting for 75.01%of the total erosion area in Gannan Region,and the highest erosion was32.13×10~6t/a.The value of soil retention capacity ranged from 18.99×10~3 t/(km~2·a)to19.05×10~3 t/(km~2·a),and the peak value exhibited in forest land,25.98×10~3 t/(km~2·a)to 26.20×10~3 t/(km~2·a).(3)The value of soil retention capacity in the boundary was higher than that in the central,increase first and then decrease with altitude,is a single peak curve with an extreme value of 52.85×10~3 t/(km~2·a),increase with the slope.The distribution of industries under development intensity is different,resulting in different soil retention intensity.(4)Soil retention capacity and NDVI was positive correlated(p<0.01).High-high agglomeration area distributed in the northern,western,and southern parts,high-low agglomeration area distributed in Central Region,including Yudu County,and low-low agglomeration area distributed in Zhanggong County,Gan County,Nankang County.(5)From 2000 to 2018,slope had the most significant impact on soil retention capacity,followed by elevation and NDVI;among the Two-Factor Interaction Detector,elevation∩slope had the highest impact intensity,indicating that the synergistic effect of slope and elevation had the greatest impact on soil retention capacity.After strengthening soil and water conservation management measures in Gannan Region,the soil erosion capacity of other woodlands decreased the most(27.32%),indicating that soil and water conservation management measures played an important role in improving soil conservation function in in Gannan Region.The soil retention capacity in Gannan Region was highly associated with land use type,elevation,slopes,NDVI,and economic development level.Among them,slope,elevation and NDVI are the most critical influencing factors.To improve the value of soil retention capacity,in low-altitude and low-slope areas soil,protection measures were suggested to enhanced,reduce the soil erosion and ecological risk in mountainous areas.