Spatiotemporal analyses and associated driving forces of vegetation coverage change in the Loess Plateau
ZHAO An-zhou1,2,3, LIU Xian-feng2,3, ZHU Xiu-fang2,3, PAN Yao-zhong2,3, CHEN Shu-chen2,3
1. College of Resources, Hebei University of Engineering, Handan 056038, China;
2. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China;
3. College of Resources Science and Technology, Beijing Normal University, Beijing 100875, China
Based on the MODIS-NDVI data, this study investigated the patterns of spatiotemporal variation of vegetation coverage in the Loess Plateau during 2000~2014, using the methods of linear regression, Mann-Kendall, correlation analysis and Hurst. In addition, potential factors affecting NDVI variations were identified. The results are as follows: 1) the Normalized Difference Vegetation Index (NDVI) of this study region was significantly increased significant, with a linear tendency being 0.0693/10a during 2000~2014, and vegetation restoration was characterized by three fast-growing periods. 2) As for spatial distribution, NDVI showed a decreasing trend from southeast to the northwest. High values of NDVI were mainly found in Southeast soil stone mountain area and valley plains area. 3) The area with improved NDVI was larger than the degraded area, and accounting for 88.24% and 11.76% of the total study area, respectively. 4) Result of Hurst analyses indicated 50.07% of the study area will keep the current NDVI change tendency in the future. The area with a continuous NDVI increase was predicted to account for 43.98% of the study area. The area, in which NDVI was changed from increase during 2000~2014 to decrease in the future, was predicted to account for 44.28% of the study area. 5) The spatial variation of NDVI was affected by Digital Elevation Model (DEM) and slope. The NDVI was best in the region with the altitude around 3500m and the region with the altitude below 500m. The NDVI was increased with the increase of the slope. 6) The NDVI was mainly affected by the precipitation, and the NDVI was increased with the increase of the precipitation. 7) Human activities can induce both negative effect (through urbanization) and positive effect (through the implementation of Grain to Green).
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