Water Yield–Carbon Storage Trade-Offs Under Future Land-Use and Climate Scenarios in Heilongjiang Province: Implications for Regional Sustainability

Climate and land-use change can affect water provision and carbon storage differently, complicating the balance between agriculture and ecological conservation. CMIP6, PLUS, and InVEST were combined for six 2032 scenarios in Heilongjiang Province. Water yield increased and was generally higher under SSP585 than SSP245, while carbon storage declined. Cropland protection produced the highest water yield and ecological conservation the greatest carbon storage. Their contrasting responses matter to the region’s long-term sustainability. Among the examined influencing factors, the digital elevation model (DEM) had the highest explanatory power for the spatial differentiation of water yield (q = 0.3578). For carbon storage, the q statistic of water yield was the highest among the selected factors (q = 0.4648), suggesting a strong statistical explanation of spatial variation rather than a causal effect. The explanatory power was further enhanced by interactions among the examined factors. Overall, water yield and carbon storage in Heilongjiang Province exhibited different spatiotemporal patterns and a significant negative spatial association. These results provide a scenario-based reference for territorial spatial optimization and the coordinated management of water yield and carbon storage, while their interpretation should remain within the assumptions and parameter settings of the models used in this study.