Climate and Anthropogenic Influences on the Spatiotemporal Change in Degraded Grassland in China

Grassland ecosystems in China are generally fragile, and have suffered severe degradation and desertification in recent decades. Understanding these changes and their drivers is crucial for projecting ecosystem dynamics. This study investigated the spatiotemporal variation of grasslands in China, and quantitatively assessed the influence of natural and anthropogenic factors using net primary productivity (NPP) from 2000 to 2014. The results showed a net increase in total grassland area of 1.30 × 105 km2, and the annual NPP increased significantly from 119.37 to 140.67 g C/(m2·a). Restored grassland dominated the research area, but the spatial distribution of grassland health was highly heterogeneous. Climate change contributed most to the recovery of degraded grasslands, especially in Inner Mongolia and Qinghai, where it was the dominant influence for 83.21% and 87.06% of the total grassland areas, respectively. Meanwhile, human activities contributed to the mitigation of grassland degradation in Tibet and Xinjiang. The opposite occurred in some localized areas of Inner Mongolia and Xinjiang. This suggested that restoration projects should be tailored to alleviate local grassland retrogression and adapt to unexpected events such as concentrated degradation.