[Dynamics and Attribution of Vegetation Coverage in the Water-source Area of the Central South-to-North Water Diversion from 2000 to 2022].

Abstract

The water-source area of the central South-to-North Water Diversion （WSA-CSNWD） is a nationally strategic water source and an important ecological function protection area in China. Studying the dynamics and causes of fractional vegetation coverage （FVC） is crucial for the protection and restoration of the ecological environment in WSA-CSNWD, as well as for ensuring the successful operation of the central South-to-North Water Diversion project. By utilizing MODIS NDVI data from 2000 to 2022, combined with land use data, meteorological data, human footprint data, and water body data, this study employs trend analysis, correlation analysis, regression analysis, and statistical analysis to explore the spatio-temporal dynamic changes of FVC in WSA-CSNWD and its underlying causes. The results indicate that： ① The WSA-CSNWD exhibited high vegetation cover with a significant increasing trend of FVC during 2000-2022 at an average annual growth rate of 0.004 0 per year. From 2000 to 2022, there was a significant decrease in FVC area within WSA-CSNWD accounting for 1.301%, primarily located in urban areas； meanwhile, there was a substantial increase in FVC area accounting for 84.965%, mainly distributed across grasslands and areas influenced by human activities. ② Surface temperature and human activities were identified as key factors influencing FVC change within WSA-CSNWD. In areas with significant increases in FVC, surface temperature exhibited a negative correlation with FVC change, while human footprint intensity showed a positive correlation with FVC change-indicating that human activities played an important role in promoting changes to vegetation coverage. ③ Human land use management, including water conservation, ecological environmental protection, and restoration projects, was identified as the primary driver behind vegetation greening in this area. Forests, grasslands, and farmlands accounted for 45%, 47%, and 4%, respectively, of areas where FVC significantly increased. These findings indicate that the observed increase in FVC was primarily attributed to human land use management practices, as WSA-CSNWD is located in a temperate subhumid North subtropical monsoon climate region and serves as both a nationally strategic water source and an important ecological function protection area in China.