Analyzing the spatiotemporal evolution and driving force of vegetation cover in the Baoji area from 2001

Vegetation influences the energy balance of the Earth-atmosphere system in the global change and is a sensitive indicators of natural and human factors to environmental impact. Analysis of the status of surface vegetation cover and exploration of the driving forces that affect vegetation change will promote the restoration of regional ecology and the development of the regional economy and regional ecological civilization. This study was based on the Moderate Resolution Imaging Spectroradiometer-Normalized Difference Vegetation Index (MODIS-NDVI) combined with temperature and precipitation data from 11 meteorological stations in Baoji, as well as net primary productivity (NPP) and Baoji statistical yearbook data. We applied trend analysis, Pearson correlation analysis, and principal component analysis to analyze the vegetation in Baoji area from 2001 to 2013. The spatiotemporal evolution of vegetation cover in Baoji area under the dual effects of natural and anthropogenic driving factors was analyzed comprehensively. Results showed that: (1) From 2001-2013, the annual average NDVI in Baoji increased by 0.025/10 years, which was faster than the growth rate of vegetation coverage in the Three-North Shelter Forest Program (TNSFP) from 1982 to 2006. There were two high recovery periods of annual NDVI, that is, 2001 to 2002 and 2003 to 2004; (2) Overall, vegetation cover was mildly improved, followed by unchanged and moderately improved, severely and moderately degraded. The restoration of vegetation cover exhibited a steady increasing tendency (except individual areas of the study site); (3) Precipitation and NPP of natural factors were the main aspects restricting vegetation growth. Human factors had more influence on vegetation coverage of Baoji area than natural factors, contributing about 90% and showing a decreasing then increasing trend.