Effects of natural and human factors on vegetation normalized difference vegetation index based on geographical detectors in Inner Mongolia

Exploring the regional vegetation cover change and its driving factors are of great importance for sustaining ecological safety. In this study, we divided banners and counties of Inner Mongolia into pastoral counties and non-pastoral counties. The linear trend analysis method and geographic detector modeling were applied to examine the effects of natural and human factors on vegetation NDVI(Normalized Difference Vegetation Index) values from 2000 to 2015. The results showed that the spatial and temporal variation of vegetation coverage decreased in the western of Inner Mongolia, while increased in the eastern and southern of Inner Mongolia from 2000 to 2015, with no significant changes in the other regions. The vegetation NDVI value was improved more in the non-pastoral counties than that in the pastoral counties. In the whole Inner Mongolia, annual precipitation and soil types were the main factors driving the change of vegetation NDVI, explaining the variation of more than 22%. The interaction among all factors was higher than the individual effect of each factor. Furthermore, in pastoral counties, the interaction among all factors tended to a nonlinear enhancement and double factor enhancement, with the strongest interaction between rural households and livestock numbers on the vegetation NDVI. The interaction among all factors showed a nonlinear enhancement in non-pastoral counties, with the strongest interaction between soil types and grain yield on the vegetation NDVI.