Spatial and Temporal Patterns and Drivers of Grassland NEP in the Muri Region, 2000 to 2022

The Muri region of Qinghai Province is not only the source of important water sources, but also one of the key areas targeted by the ecological environment restoration project. The study of the Net ecosystem productivity (NEP) of grassland in the Muri region is of great importance in order to gain insight into the health of grassland ecosystems and to assess the carbon sink capacity. In this study, the net primary productivity (NPP) and NEP of the grassland in the Muri region from 2000 to 2022 were calculated using remote sensing data, meteorological data and land cover data, coupled with Carnegie-Ames-Stanford Approach (CASA) model and soil heterotrophic respiration model. The spatial and temporal patterns of NEP of grassland ecosystems over different periods from 2000 to 2022 were assessed following accuracy tests. The drivers affecting the spatial and temporal changes in NEP of grasslands in the Muri region were then explored with the help of Geogdetector. The study indicated that: (1) From 2000 to 2022, the mean annual NEP of grassland in the Muri region was 138.23 gC/m², exhibiting a significant increasing trend (p < 0.01). (2) Spatially, the NEP of grassland showed a pattern of distribution from south-east to north-west, from the center to either side and from high to low values, with 91.58% of grassland showing an increasing trend in all growth periods. (3) Climatic factors, altitude and slope are important drivers of changes in the NEP of grassland, with altitude being the most important factor influencing the NEP of grassland in this region. This study can provide valuable references for assessing the carbon sequestration capacity of grassland ecosystems and monitoring the health of grassland ecosystems in the Muri region, as well as for formulating future ecological protection policies and directions in the Muri region.