Quantitative analysis of the impacts of climate change and human activities on vegetation NPP in the Qilian Mountain National Park

The Qilian Mountain National Park（QMNP） is an important ecological security barrier and water conservation area, and exploring its vegetation Net Primary Productivity（NPP） variation is of great significance to the ecological security in Northwest China. We used methods, including unary linear regression, partial correlation analysis, and multivariate linear regression analysis and residual analysis, to analyze the space distribution of vegetation NPP and its relationship with precipitation, temperature and human activities based on the MOD17A3 remote sensing data in the QMNP from 2000 to 2019. In terms of this, we quantified the vegetation NPP influenced by the climate change and human activities, respectively. The results showed that:（1） from 2000 to 2019 vegetation NPP in the QMNP had an overall fluctuating upward trend and decreased from east to west, with a multi-year average of 113.14 g C m-2 a-1 and an average annual increase of 1.41 g C m-2 a-1;（2） The vegetation NPP was positively correlated with precipitation and temperature, with precipitation having a more significant effect on it;（3） In human activity area, the vegetation NPP presented an overall increasing trend, with 87% area increasing and 13% area decreasing of vegetation NPP in 2019 compared with those in 2016;（4） In the vegetation recovery area, climate change and human activities explained 92% and 8% of the vegetation recovery, respectively. While in the vegetation degradation area, they explained 29% and 71% of the vegetation degradation, respectively. The results can provide a scientific decision basis for ecological and environmental protection and management in QMNP.