Quantitative analysis of relative impacts of climate change and human activities on Xilingol grassland in recent 40 years

Previous studies have shown that climate changes and human activities are the main external factors affecting grassland. Therefore, quantitative assessment of their dominant role is of great significance for grassland management. This study selected Net primary productivity (NPP) as an indicator and quantitatively analyzed the relative impacts of climate change and human activities on Xilingol grassland during 1982-2018 by establishing different analysis scenarios. The results showed that the annual average grassland NPP was 251.13 g center dot C center dot m-2 center dot a-1 from 1982 to 2018 and showed an increasing distribution pattern from west to east. During 1982-2018, the grassland NPP showed a slightly decreasing trend, with annual average decreases of 0.42 g center dot C center dot m-2 center dot a-1 and changed significantly in 1998. The changing trend of grassland NPP was a significant difference during the two periods around 1998. Approximately 94.95% of the grassland showed a restoration trend in 1982-1998, and 76.47% of the grassland showed a degradation trend in 1998-2018. The climate-dominated grassland accounted for 87.76%, 75.4%, and 73.68% of the total grassland area in 1982-1998, 1998-2018, and 1982-2018, respectively. In comparison, the human-dominated grassland was 12.24%, 24.6%, and 26.32%, indicating that climate change is the main factor leading to the grassland NPP change, and human activities affect the change of NPP in local areas. Further analysis identified precipitation as the dominant climate factor affecting grassland, and mining and reclamation became the main form of human activities accelerating grassland degradation.