Climate change enhances the positive contribution of human activities to vegetation restoration in China

Ecological projects have huge impacts on vegetation restoration (VR) in China. However, are all of the effects due to human activities (HA) without the contribution of climate change (CC)? It is unclear what role CC plays in VR. Here, we quantitatively evaluate the contributions of climate change and human activities (CC_con and HA_con) to the net primary productivity (NPP) by the method of partial derivative and six different scenarios. HA contributed 61.19% to the NPP trend and controlled 32.84% of the NPP growth in China. Among the climate factors, temperature made the largest contribution to the NPP (45.89%) and had the largest control area (36.36%). CC promoted the positive HA_con in 54% of China, and in 68.35% of the area, the enhancement effect reached more than 50%. Our results answer a longstanding question and emphasize the important role of CC in enhancing the positive HA_con to VR.