Vegetation NDVI Change and Its Relationship with Climate Change and Human Activities in Yulin, Shaanxi Province of China
Journal of Geoscience and Environment Protection
Yulin is a typical ecological fragile area in China, and its vegetation ecosystem is so fragile that could be vulnerable to climate change and human activities. Spatial and temporal change of vegetation Normalized Difference Vegetation Index (NDVI) and its relationship with climate change and human activities were analyzed based on MODIS NDVI data from 2000 to 2015, as well as annual temperature and precipitation data from 2000 to 2014, and linear trend analysis, correlation and buffer analysis
... and buffer analysis were used. Result showed: 1) NDVI value was small and vegetation cover was low, but NDVI had a linear growth rate of 0.0096/annum from 2000 to 2015 in Yulin area. The area of growth trend accounted for 97.06% of the total area, while the area with decreased rate was small, which mainly had correlation with human activities, and was distributed in the southwest mountain area, urban neighborhood, and river valley in the middle and east of Yulin area. 2) Correlation analysis between NDVI and temperature, precipitation, respectively, reflected that negative correlation was between NDVI and temperature, while positive correlation was between NDVI and precipitation. Furthermore, the role of precipitation was higher than that of temperature in the process of interaction between NDVI and temperature, precipitation. 3) NDVI change process in the range of human activities indicated that the intensity of human activities in buffer_city area was higher than that in buffer_county area. Buffer_city area was divided into within 5 km area with dramatic impact by human activities, and from 5 km to 9 km area with less impact by human activities, and outside 9 km area with mini-affected by human activities.