Impacts of climate change and human activities on net primary productivity of grasslands in Inner Mongolia, China during 1982-2015.

We analyzed the impacts of climate change and human activities on the net primary productivity of grasslands in Inner Mongolia during 1982-2015. The results showed that the growth rates of actual net primary productivity (ANPP) were 1.08 and 1.36 g C · m · a in 1982-1998 and 1999-2015, respectively. Such changes were largely due to restoration, with restoration implementing in 81.6% and 76.3% of the total study area in 1982-1998 and 1999-2015, respectively. The area of degraded grasslands tends to increase. The effects of climate change and human activity varied across different types of grassland. Climate change was the main contributor to grassland restoration over the two periods, with the contribution rates being 79.3% and 94.1%, respectively. The ANPP was positively correlated with precipitation but not with temperature, indicating that precipitation was the main climate factor influencing grassland restoration. Human activities contributed most to grassland degradation over the two periods, with the contribute rate being 83.3% and 87.8%, respectively. Our results suggested that the climate change was the dominant contributor to grassland restoration, while human activities, such as increase in livestock numbers, cultivation and afforestation, accelerated grassland degradation.