Spatio-Temporary Variations of Grassland Carrying Capacity Derived from Remote Sensing NPP in Mongolia

The increase in livestock numbers and insufficient precipitation have led to a decline in pasture biomass, resulting in grassland carrying capacity (GCC) and pasture degradation. In this study, net primary productivity (NPP) data, which were derived from the Global Land Surface Satellite (GLASS) and Moderate Resolution Imaging Spectroradiometer (MODIS) datasets spanning from 1982 to 2020, were firstly converted into aboveground biomass (AGB) and then used to estimate and assess long-term trends of GCC across Mongolia. Between 1982 and 2020, Mongolia's climate exhibited a warming and drying trend. Although livestock number have generally increased since 1982, certain years experienced declines due to winter dzud and summer droughts. These climatic changes reduce net primary productivity (NPP), further weakening the regenerative capacity of grasslands. Simultaneously, the increasing livestock number intensifies grazing pressure, surpassing the GCC. Finally, this grassland carrying capacity exceeded (GCCe) leads to reduced vegetation cover and desertification of grassland. Spatially, vegetation productivity and precipitation exhibited a declining gradient from north to south, whereas temperature increased progressively from to north to south. GCC assessments revealed that the eastern region of Mongolia could support current livestock number sustainably. In contrast, the western and southern regions, as well as parts of northern Mongolia, exhibited moderate to critical levels of grassland utilization. This study enabled a detailed analysis of grassland dynamics and climatic impacts, providing an assessment of temporal changes in Mongolia's GCC.