三江源地区植被盖度与居民点的关系研究

The Relationship between NDVI and Residential Sites across "Three-River-Source" Area

本文基于人口与环境相关联的地理视角,运用最大化合成法、缓冲区分析法,研究三江源地区植被分布与人口、居民点的关系。研究表明:①从大的空间尺度看,居民点主要分布在NDVI条件好的区域;NDVI条件差的区域,居民点分布较少;②在几十公里距离范围内,植被盖度与离居民点的距离的关系是:居民点密度大的地区,随着距居民点距离的增加NDVI呈上升趋势;居民点密度居中的地区,随着距居民点距离的增加NDVI呈下降趋势;居民点密度小的地区,NDVI与距离居民点远近没有明显相关关系;③对典型牧业居民点小尺度范围内人口分布与NDVI关系的研究发现,距居民点2km范围内,由于人类的放牧活动造成了植被的退化,NDVI较低;2～4km范围内,植被受人类放牧活动影响越来越小,随着距离的增加NDVI呈显著上升态势;4～10km范围内,因为自然条件的差异,NDVI随着距离的增加逐渐变小;④在1998年-2009年即三江源生态治理工程期间,NDVI总体上是上升的。

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.