Uncovering the impact of multiple determinants on vegetation NPP in Inner Mongolia

Vegetation in arid and semi-arid regions is a critical component of global ecosystems, providing essential ecological services both locally and globally. However, these regions are increasingly threatened by rapid vegetation degradation due to global warming and unregulated human activities. Understanding the determinants of dryland vegetation growth and their evolution under the influence of climate change and anthropogenic disturbances is therefore vital. Focusing on Inner Mongolia, the primary factors influencing grassland growth were systematically analyzed using Geodetector and structural equation modeling, leveraging multi-source remote sensing data and statistical information. We considered ten potential determinants, including six natural factors (elevation, slope, precipitation, temperature, solar radiation, and soil moisture) and four anthropogenic factors (land use, livestock population, GDP, and population density). The results indicate a significant upward trend in NPP across Inner Mongolia, with an average increase of 4.69 g·C/m² between 2000 and 2020, particularly in the southeast and southwest regions. Soil moisture emerged as the most influential factor affecting NPP, followed by land use, air temperature, and precipitation. While the influence of these primary drivers on NPP remained stable over time, the impact of livestock numbers showed a noticeable decline. Additionally, interactions among these factors generally amplified their individual effects, particularly the interaction between soil moisture and precipitation, which had a substantial impact on NPP. Notably, 93 % of solar radiation's influence on vegetation was mediated through its effects on other factors. The study also highlighted the critical role of land use changes, particularly the management of sandy land and the conversion of grassland to cropland, in enhancing NPP. The findings underscore the need to improve grassland management strategies, promote desertification control, regulate cropland development, and advance ecologically sustainable practices in response to climate change in arid zones.