## 3 Results  
### Spatiotemporal Trends of RSM, PRE, and GPP  
Between 2000 and 2022, the multi-year average RSM within the study region was 0.143 m\({}^{3}\)/m\({}^{3}\), exhibiting an overall upward trend (Figure S1). Increases in RSM were primarily observed in grassland and forested areas, whereas declines were predominantly found in bare or sparsely vegetated lands (Figure 3). Spatial heterogeneity in RSM was pronounced; grasslands and forests displayed higher annual mean values coupled with lower local variability, in contrast to bare or sparsely vegetated regions, which generally had lower RSM but greater spatial variability among adjacent locations. Notably, the southwestern sector of the study area experienced a significant downward trend in RSM, which, when considered alongside precipitation data (Figure 3b), may be linked to decreased precipitation levels. Conversely, agricultural lands exhibited a marked increase in RSM, likely attributable to anthropogenic influences such as irrigation and land management practices. Regarding PRE, 57% of the study area showed increasing trends, with particularly significant rises in the southeastern region, predominantly affecting grasslands, forests, and agricultural lands. Conversely, 43% of the area experienced decreasing PRE trends, mainly concentrated in the northwestern and southwestern zones. The most pronounced PRE decline occurred in the southwest, potentially contributing to the observed reduction in RSM in that region. Over the 2000-2022 period, average summer precipitation accumulation ranged from 42 to 67 mm, characterized by notable interannual variability. GPP during summer also demonstrated a significant upward trend across the study area, increasing at a rate of 0.455 gCm\({}^{-2}\)yr\({}^{-1}\). Approximately 82% of the region exhibited rising GPP trends, while 18% showed declines. The most substantial increases in GPP were recorded in grasslands, forests, and agricultural lands. In contrast, bare and sparsely vegetated areas maintained consistently low GPP values due to limited vegetation cover. A notable decrease in GPP was observed in the northwestern portion of the study area, potentially linked to intensive human exploitation activities.  
An analysis of the spatiotemporal patterns within the study area revealed that in grasslands, forests, and agricultural lands, both relative RSM and PRE exhibited increasing trends, accompanied by significant upward trends in GPP across these regions. These findings suggest that increases in RSM and PRE contribute to the enhancement of GPP. Conversely, in the southwestern portion of the study area, GPP demonstrated a declining trend that corresponded with decreases in both RSM and PRE, indicating that concurrent changes in RSM and PRE may either promote or inhibit variations in GPP depending on their directional trajectories. Nevertheless, the spatial distribution of GPP increases did not entirely overlap with regions experiencing increases in RSM and PRE. This partial spatial decoupling implies that the independent influences of RSM and PRE on GPP warrant further detailed investigation to elucidate their distinct roles in driving vegetation productivity dynamics.