The influences of climate factors on net primary productivity of Gannan grassland, the Qinghai-Tibet Plateau, China

In the context of global climate change, the research on spatiotemporal dynamics of grassland productivity in Gannan and its influencing climate factors are of great significance for clarifying the role of grassland ecosystems in carbon cycling, regional ecological protection and ecological security. Based on meteorological and remote sensing data, the improved CASA model was used to simulate the grassland net primary productivity (NPP) in Gannan, and applies sensitivity analysis to explore the climate factors’ impacts on grassland NPP during 2000 to 2020. This study found that: (1) from 2000 to 2020, NPP increased at a rate of 1.82 gC/(m²·a) (P > 0.05) and temperature, precipitation, and solar radiation in Gannan demonstrated significant increases with the rates of 0.03 °C/a, 7.11 mm/a and 18.46 MJ/(m²·a) respectively. This suggested that the warming and humidification of climate has promoted the growth of grassland in Gannan; (2) temperature, precipitation, and radiation contributed to NPP changes by 29.9%, 32.4%, and 37.7%, respectively; (3) the regions where temperature, precipitation and solar radiation played leading roles are respectively distributed in the mid-west and southwest, the north and northeast, and the central and southeastern parts of Gannan, which implies spatial climate factors' disadvantage governs grassland NPP changes; (4) for the whole of Gannan, the areas of grassland NPP with positive sensitivity to temperature accounts for 91%, which indicates that climate change may facilitate Gannan grassland NPP in future.