Vegetation response to climatic variation and human activities on the Ordos Plateau from 2000 to 2016

Determination and analysis of the effects of climatic variation and human activities on vegetation changes since the implementation of intensive ecological projects in 2000 are critically important for the restoration of vegetation on the Ordos Plateau, one of the areas that suffer from the worst vegetation degradation, the most concentrated coal and gas exploitation, and the highest ecological risks in China. This study was performed to establish and validate a nonlinear regression model to express the relationships between the normalized difference vegetation index (NDVI), precipitation, and air temperature in areas with scarce human activities, as identified from the Global Human Influence Index Datasets. This model was then applied to the whole plateau with data on cumulative precipitation and average air temperature with the consideration of the delayed effects to simulate temporal NDVI changes induced by climatic variation. The residual trend was then computed as the slope of the difference between the actual NDVI and the simulated value to analyze the human impact on vegetation. The results show that the plateau’s vegetation had experienced a significant greening trend from 2000 to 2016 under a warmer and wetter climate and with the impact of human activities; compared to air temperature, precipitation played a leading role in vegetation greening in most parts of the plateau, and human activities had a significant positive impact in 22.0% of the plateau and a significant negative impact in 0.66% of the plateau ( p < 0.1). More effective programs of ecological protection and restoration must still be conducted by the government and other organizations.