The spatiotemporal pattern of grassland NPP in Inner Mongolia was more sensitive to moisture and human activities than that in the Qinghai-Tibetan Plateau

The Qinghai-Tibet Plateau (QTP) and the Inner Mongolia Plateau (IMP) are important ecological barriers in China, and their grassland ecosystems are extremely fragile. Recently, the grassland ecosystems in both regions have been at risk of degradation owing to climate change combined with anthropogenic disturbance. However, comparative studies on how the driving factors of natural and human activities affect grassland spatiotemporal patterns on the QTP and IMP have been limited. Therefore, net primary productivity (NPP) was chosen as an indicator to understand its spatiotemporal patterns and driving mechanisms in this study. The spatiotemporal variation and spatial autocorrelation of NPP in the QTP and IMP grasslands NPP from 2000 to 2018 were analyzed. The partial least squares structural equation model and geographical time-weighted regression model were used to develop a research framework to explore the influence of natural factors, human activities and their interactions on the grassland NPP of the QTP and the IMP. Overall, the results showed that the spatiotemporal variations in grassland NPP of the QTP and IMP increased, with localized degradation from 2000 to 2018, with a faster NPP recovery in the IMP grassland NPP than in the QTP grassland NPP. Both the QTP and IMP showed high degrees of spatial autocorrelation. The driving factors explained 78.2 % and 80.6 % of the QTP and IMP grassland NPP, respectively. Moisture was the dominant driver but had a greater impact on the IMP than on the QTP. Among the human activity factors, atmospheric acid deposition had a negative influence on the QTP grassland and a positive impact on the IMP grassland. Socioeconomic activities presented stronger direct negative impact on IMP grassland. The indirect effects of human factors on the QTP through terrain and climate were greater. The grassland NPP exhibited significant spatiotemporal heterogeneity in response to the main driving factors of the QTP and IMP. This study explores the divergent mechanisms driven by natural and anthropogenic attributes of grassland NPP and provides information to scientifically guide the restoration of grassland ecosystems.