Detecting and analysis of spatial and temporal variation of vegetation cover in the Loess Plateau during 1982-2009

Time-series GIMMS and SPOT VGT NDVI datasets, which served as an evaluation index of the vegetation cover, were used in this paper to detect and analyze the spatial and temporal variation of vegetation cover in the Loess Plateau from 1982 to 2009. Results showed that before the large-scale implementations of vegetation construction (1982-1998), the annual mean NDVI of the Loess Plateau fluctuated in a narrow range yearly; most places indicated no significant changes in NDVI except for some improvement in a few places. However, since the large-scale implement of vegetation construction in 1999, the annual mean NDVI of the Loess Plateau has increased significantly. Most regions (covering 66.12% of the total area) on the Loess Plateau showed significant positive correlation between NDVI and time over the past decade, especially in the part traversed by the Loess Hilly-gully Region, where the achievements of vegetation construction were quite noticeable. Moreover, the vegetation cover in 15°～25° and 6°～15° slope areas experienced great improvement from 1999 to 2009, which may be helpful to control soil and water losses. The large-scale implementations of vegetation construction accelerated the vegetation restoration in the Loess Plateau. Nevertheless, regions with sparse vegetation on the Loess Plateau still covered a great part by 2009, so it is necessary to further strengthen the ecological environment construction in the future.