Thresholds of vegetation cover change and regulatory strategies in the Hanjiang River basin
WANG Zhu
ZHANG Guanhua
WANG Yifan
YANG Wenjun
Abstract：The Hanjiang River basin is not only the core water source area for the Middle Route of the South-to-North Water Diversion Project but also a key ecological node within the Yangtze River basin.Vegetation change in this region is directly related to the implementation of major national strategies and regional sustainable development.Based on time-series NDVI data from 2000 to 2023,combined with the Geodetector model,Random Forest algorithm,and Partial Dependence Plot method,the driving mechanisms of vegetation change in the Hanjiang River basin were systematically revealed from three aspects:spatiotemporal variation characteristics,identification of driving factors,and analysis of response thresholds.Differentiated regulatory strategies for the upper,middle,and lower reaches were also proposed.The results show that vegetation in the basin has generally improved since 2000,but with marked spatial differences,presenting a pattern of continuous improvement in the upper reaches,fluctuating changes in the middle reaches,and intensified degradation in the lower reaches.Vegetation change in the upper basin is mainly influenced by natural factors,with elevation,annual precipitation,and mean annual temperature as the key drivers,while vegetation in the middle and lower reaches is affected by the combined influence of land use and geomorphological type.Nonlinear relationships exist between key drivers and NDVI.Optimal vegetation conditions in the upper basin occur under precipitation of 1600～1800 mm,elevation of 1500～2000 m,and mean annual temperature of 7～10℃.In the middle and lower reaches,NDVI shows dual inflection points at elevations of about 100 m and 500 m,reflecting sensitive areas and critical thresholds of vegetation ecosystems to external disturbances.Based on these findings,a"zonal classification and coordinated management"vegetation restoration pathway is proposed,establishing a comprehensive governance system integrating engineering measures,ecological restoration,and institutional safeguards to support ecological security enhancement and policy-making in the basin.
Keywords：normalized difference vegetation indexdriving factorsresponse thresholdsregulatory strategieswater source area of the Middle Route of the South-to-North Water Diversion ProjectHanjiang River basinvegetation regulation
Publication Date：2025-09-30
Online Publishing Date：2025-10-21(First online date of this platform, not the publication date of the document)
Pages：10( 59-67,72 )