Possible Influences of Land Use and Cover Change on Vegetation Cover: A Case Study in China's Yongding River Basin

Understanding the influence of land uses on vegetation cover can guide both the restoration and the historical reconstruction of vegetation communities. In this study, we developed a linear decomposition model for vegetation cover, with the model's endmembers determined using a pixel purity index. Using remote sensing images from 1978, 1987, 2000, and 2005, we calculated normalized-difference vegetation index (NDVI) values, and used the linear decomposition model to estimate the changes in vegetation cover in China's Yongding River Basin due to climate change. We performed regressions among NDVI values, climate factors, and slope, and reconstructed NDVI (thus, vegetation cover). Based on classification of the remote sensing images from the four dates, we analyzed the influence of land use and cover change on vegetation cover under two climate scenarios: (1) The climate in the previous period remains unchanged, so the precipitation and temperature in 1978, 1987, and 2000 replaced the values in 1987, 2000, and 2005, respectively. In this scenario, the decrease in vegetation cover from 1978 to 1987 in most of the basin ranged from 20 to 60 %. The vegetation cover in most of the basin increased from 1987 to 2000. From 2000 to 2005, vegetation cover decreased in northern parts of the basin but increased in the middle, eastern, and southern parts. (2) The 1978 precipitation and temperature values remain unchanged. In this scenario, vegetation cover increased by 40 to 60 % from 1987 to 2000 in the eastern part of the basin and by 0 to 40 % in the middle and western parts. From 2000 to 2005, vegetation cover decreased in most of the basin, but increased in some middle and eastern areas.