Vegetation dynamics influenced by climate change and human activities in the Hanjiang River Basin, central China

Assessing the dynamics of vegetation and its response to environmental changes is essential to understanding ecosystem changes and the sustainable use of natural resources. In this study, we investigated the impacts of climate change and human activities on vegetation growth in the Hanjiang River Basin. We classified the basin into the portion mainly affected by climate change (VClimate) and the portion affected by both climate change and anthropogenic activities (VClimate+Human). Using an improved residual trend method that considers both lag effect and nonlinear response, we analyzed the relative contributions of climate change and human activities to observed NDVI changes. Results suggest that the basin experienced a statistically significant increase in growing -season NDVI during 2001-2016 (0.047 decade-1). Precipitation was the dominant climatic factor for NDVI change in VClimate+Human, whereas precipitation and temperature were nearly equally important for NDVI change in VClimate. On average, both climate change and human activities promoted vegetation growth during the study period, and their average contributions were 41.4 % and 15.5 %, respectively. In particular, climate change and human activities in general enhanced vegetation growth in non-urban areas, while human activities mainly reduced vegetation growth in urban areas. The findings of this study can benefit regional ecological restoration and environmental management projects.