Spatiotemporal Change of Vegetation Coverage in Shaanxi Province from 1998 to 2008

The vegetation coverage is an important indication of the situation of ground vegetation,and it is the foundation data for describing ecological system,and is also the main factors affecting soil erosion.Based on 372 images of SPOT4 VEGETATION(S10) data from April 1998 to July 2008,the change trend of the yearly maximum NDVI,the inter-annual changes of yearly maximum NDVI and monthly maximum NDVI,and the dynamic change and spatial distribution of vegetation coverage in Shaanxi Province are analyzed by means of maximum value composites(MVC),one-dimensional linear regression and differential approach.The results show that the yearly maximum NDVI of Shaanxi Province is on the whole improved from 1998 to 2008,but the inter-annual change trend of the monthly maximum NDVI has a great difference among different months,the changes during the adjacent two years of both the yearly maximum NDVI and the monthly maximum NDVI have a great difference,and the vegetation degradation and improvement appear fluctuantly.The change of vegetation coverage is obviously during 1998 to 2008,and the vegetation is best in August and September.Vegetation coverage of most regions is increased,the obviously increased regions mainly appear in northern parts of Shaanxi Province(southeast parts of Yulin and north part of Yan’an),in south central of Baoji,parts of Xi’an,Shangluo,Ankang are also improved.