NDVI-Based Analysis of the Influence of Climate Changes and Human Activities on Vegetation Variation on Hainan Island

The spatiotemporal characteristics of vegetation variation on Hainan Island were explored with normalized difference vegetation index (NDVI) data from 2001 to 2016 on the basis of a regression-analysis method. The impact of climatic factors and human activities on vegetation variation was assessed in different climate regions by residual analysis. Our study indicated that vegetation regions with significant improvement were primarily located in the coastal part of the semi-arid, central semi-humid, central mountainous humid, and parts of the humid regions. More serious vegetation degradation was observed in the northern part of the semi-humid region, eastern parts of the humid region, and the southern semi-arid and semi-humid regions. The relationship of NDVI with precipitation was stronger than that with temperature in the humid and semi-arid regions, and drought was the critical factor influencing vegetation changes in the semi-arid region due to comprehensive actions of rising temperature and declining rainfall. The findings of residual analysis highlighted that the degradation of vegetation was mainly triggered by anthropogenic factors: the rapid development of urbanization in the northern part of the semi-humid, and the southern semi-arid and semi-humid regions, and excessive aquaculture in the eastern parts of the humid region. The results are expected to provide an effective foundation of formulating environmental and ecological sustainability policies on Hainan Island.