The Relationship between NDVI and Residential Sites across "Three-River-Source" Area
三江源地区植被盖度与居民点的关系研究

Human activities have strong impacts on vegetation. This paper analyzed the relationship between NDVI and the distribution of population and residential sites in Sanjiangyuan area. First, correlation analyses were done to analyze the relationship between population/village density and NDVI at the town/township level. Second, a buffer zone analysis for NDVI was carried out for different buffer widths and distances from residential sites. Population data for the year 2000 came from the Fifth National Census, while population data for 2008 came from a drinking water survey by the Bureau of Water Resources, Qinghai Province. NDVI data came from NOAA satellite data. We found that population density and residential density are positively correlated with NDVI, reflecting the rational selection of people to live in better conditions. Different relationships between NDVI and distance from village were found for different village densities. At the highest village density, NDVI increases along with the distance from villages, revealing that heavy human activities have damaged vegetation. At low village density NDVI does not change with distance; at medium village density NDVI decreases along with distance. For pastoral villages in pure pasture areas, NDVI decreases along with distance within 2 km, and NDVI increases for distances 2 km to 4 km; NDVI decreases again at distances larger than 4 km. There is a increasing trend of NDVI in Sanjiangyuan from 1998-2009 and shows that vegetation has improved in the first phase of the ecological rehabilitation project.