Study on Spatiotemporal Variations of Vegetation Cover in the Western Qinling Mountain Areas During the Period from 2000 to 2010 -A Case of Longnan of Gansu,China
As the main topic of terrestrial ecosystem study,vegetation cover change gained extensive attention in the process of global climate change and sustainable development recently.Based on MODIS NDVI data from June to October during the period from 2000 to 2010,taking Longnan City as a case area,we developed the calculation method of vegetation cover(V_c)by using Pixel Dichotomy model and analyzed the spatiotemporal variations of vegetation cover in the western Qinling Mountain areas by using simple linear regression and standard deviation method.The results showed that vegetation cover remained stable and significantly correlated with temperature and precipitation during the decade.The vegetation cover of 90%of study area showed the stability with small annual variation and also was consistent with the spatial distribution of forest land;while the vegetation cover in other 10%of study areas showed the growing tendency with significant variations and also was consistent with the spatial distribution of farmland and grassland,especially in Huicheng Basin,Xili Basin and adret slope of Bailong River Valley,which indicates that the Grain for Green project has the great contribution to vegetation cover increase.This study proved the effect of ecological construction in the western Qinling Mountain areas since late last century.All the findings can also provide references for local ecological environment construction and sustainable development.