Contributions of climate change and human activities to vegetation dynamics in Qilian Mountain National Park, northwest China

A series of policies have been implicated in the Qilian Mountain National Park (QLMNP) to combat climate change (CC). Distinguishing the impacts of CC and human activities (HA) on vegetation dynamics in QLMNP is crucial for policies implementation and ecological conservation. Here, we quantify the contributions of CC and HA to net primary productivity (NPP) using partial derivatives and dividing them into six different scenarios. The results indicated that the average annual NPP over the whole park significantly increased (2.14 g C m−2 yr−1) and a major portion of QLMNP (74.39%) exhibited a significant vegetation restoration; only 0.14% of the park underwent significant degradation during 2000-2019. Precipitation was the dominant climatic factor that influenced vegetation dynamics in QLMNP (56.66%), while the influences of temperature and solar radiation account for 28.92% and 14.42%, respectively. The climatic factors were positively correlated with NPP in most regions of the QLMNP. The relative contributions of CC and HA to the increase in NPP were 39.70% and 60.30%, respectively. The HA-dominated (NPP) areas contained most ecological restoration projects. In addition, substantial differences were observed in the CC-dominated and HA-dominated areas; 70.73% of the CC-dominated areas and 29.27% of the HA-dominated areas showed the decrease in NPP. Moreover, CC-dominated areas were mainly distributed in low-value NPP areas, and the precipitation was negatively correlated with NPP in this area. In general, CC and the ecological restoration projects made a positive contribution to the eco-environment of QLMNP.