1. Institute of Scientific and Technical Information, Chinese Academy of Tropical Agricultural Sciences/ Key Laboratory of Practical Tropical Crop Information Technology in Hainan, Haikou 570000, China 2. Key Laboratory of Agricultural Remote Sensing, Ministry of Agriculture, Beijing 100100, China
Using MODIS normal difference vegetation index (NDVI) data from 2001 to 2015 and climate data acquired from 7 meteorological stations in Hainan Island, the authors analyzed vegetation variability under the influence of climate variations and human activities based on residual analysis method, unary trend curve regression model and relative role analysis method in Hainan Island. The results showed that NDVI observed by remote sensing (MODIS NDVI) increased over the past 15 years with a rate of 0.024 per ten years in Hainan Island. The proportions of increasing vegetation and decreasing vegetation areas were 77.77% and 22.23%, respectively. As identified by remote sensing observations in Hainan Island, the relative roles of climate changes and anthropogenic activities in vegetation increase areas were 31.04% and 68.96%, while the roles of climate variations and human activities in vegetation decrease areas were 35.03% and 64.97%, respectively, indicating that human activities played a major role in vegetation changes. The area of increased vegetation mainly influenced by human activities (relative role >50%) accounted for 80.79% of the whole increase vegetation area, which was associated with the large-scale rubber plantation in these areas. In contrast, the area of reduced vegetation mainly induced by human activities (relative role > 50%) accounted for 75.59% of the reduced vegetation regions, which may be induced by the increased urbanization and urban expansion in coastal regions. On the whole, climate changes could promote the vegetation growth, whereas human activities played a greater role in the vegetation increasing than in the vegetation decreasing.
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