## 5 Conclusions  
This research systematically disentangled the effects of RSM and PRE on GPP during the summer months from 2000 to 2022 within arid and semi-arid regions of China by employing a data binning approach. This methodological framework effectively controlled for the influence of individual variables on GPP, thereby allowing for the isolation of independent responses to variations in single factors while holding other environmental conditions constant. The findings revealed a significant upward trend in summer GPP, quantified at 0.455 gCm\({}^{-2}\)yr\({}^{-1}\), throughout the study region, whereas PRE did not exhibit statistically significant trends. Spatial analysis indicated that increases in GPP and RSM were primarily concentrated within grasslands, forests, and agricultural areas. Although coupled interactions between RSM and PRE were observed in China's arid and semi-arid areas,their respective influences on GPP operated independently of this coupling mechanism. Decoupling analysis demonstrated that under conditions of elevated RSM (\(SA_{RSM}>1\) and \(SA_{PRE}<-1\)), \(SA_{GPP}\) increased on average by 0.249, after accounting for confounding effects of E and RUM, a significantly greater increment compared to the \(-0.088\) change observed under high-PRE conditions (\(SA_{PRE}>1\), \(SA_{RSM}<-1\)). Regions dominated by RSM effects comprised 62.13% of the total study area, with particularly pronounced dominance in barren or sparsely vegetated lands, grasslands, and agricultural ecosystems. Furthermore, the influence of RSM on GPP intensified with increasing aridity; in extremely arid zones (\(SAI\leq 0.4\)), \(\Delta SA_{GPP}\) (\(SA_{RSM}\) \(|SA_{PRE}\)) peaked at 0.577, whereas this value declined to 0.409 in semi-arid-to-semi-humid regions (\(SAI\geq 0.9\)). These results underscore the critical role of RSM retention capacity in sustaining vegetation productivity under conditions of heightened moisture limitation. This research delineates the distinct response mechanisms of vegetation productivity to RSM and PRE within the arid and semi-arid areas of China. It offers a theoretical foundation for the optimization of water resource management strategies aimed at ecological restoration in dryland environments. The findings indicate that RSM constitutes the principal regulatory factor influencing vegetation carbon sequestration capacity in these areas. This insight is expected to substantially improve the precision of carbon cycle modeling in arid zones under scenarios of global environmental change. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/atmos1608993/sl](https://www.mdpi.com/article/10.3390/atmos1608993/sl)]([https://www.mdpi.com/article/10.3390/atmos1608993/sl](https://www.mdpi.com/article/10.3390/atmos1608993/sl)), Figure S1: Spatial distribution of mean values, and temporal variations of GPP, RSM, and PRE in the study area from 2000 to 2022. Figure S2: Absolute contributions of RSM, PRE, and RUM to MODIS GPP calculated via ridge regression. Figure S3: Decoupling the effects of RSM and PRE on MODIS GPP. Figure S4: The influence of RSM and PRE on MODIS GPP in the study area. Conceptualization, J.N. ; methodology, J.N. and Z.L. ; software, H.L. ([PERSON]) and Z.L. ; validation, H.L. ([PERSON]) and M.L. ; formal analysis, P.Z. ; investigation, Z.L. ; resources, P.Z. ; data curation, Z.L. ; writing--original draft preparation, Z.L. ; writing--review and editing, Z.W. and P.Z. ; visualization, H.L. ([PERSON]); supervision, J.N. ; project administration, H.L. ([PERSON]); funding acquisition, P.Z. All authors have read and agreed to the published version of the manuscript. The Faculty of Geographical Science at Beijing Normal University received funding from the National Natural Science Foundation of China (No. 42305148) to support this research. Not applicable. All data used in this study are openly accessible, with detailed data sources described in Section 2.2 of the article.