Monitoring and evaluation of the effects of Grain for Green Project in the upper and middle reaches of China's Yangtze River.

Abstract

Based on the comprehensive interpretation of GIS, we analyzed the normalized vegetation index (NDVI), land use types and digital elevation model (DEM), and revealed the results achieved by the Grain for Green Project in 84 prefecture-level regions in the middle and upper reaches of the Yangtze River. The results showed that the NDVI was growing in this area from 2000 to 2015. Compared with 2000, 2.1% of the farmland was no longer cultivated. 25% of the farmland with slope more than 35°, and 2.7% of the farmland with the slope of 25° to 35°, and the most part of moderate slope farmland had been converted. Arable land was mainly converted to woodland and grassland. The coverage of forest and grassland significantly increased, with an enhancement of 21.9%. The land area of low vegetation coverage was greatly reduced. The area with vegetation coverage less than 10% decreased by 95.3%, while the land area of high vegetation coverage significantly increased. The soil erosion intensity generally reduced. The land area with mild, strong, extremely strong soil erosion grade were all reduced by more than 10%, whereas severe soil erosion had not been alleviated. The proportion of forest coverage was 60% in this area. The magnitude of vegetation coverage changes varied in different periods. The spatial distribution was uneven, with higher coverage in the east than in the west. More works are needed to strenthen the management of Grain for Green Project in this area.