Identification of ecosystem service trade-off mitigation zones and nonlinear response mechanisms in natural and planted forests in the context of climate change

Forests, as ecological land, serve as vital carriers for improving the ecological environment and mitigating trade-offs in ecosystem services (ESs), offering a natural solution for achieving sustainable ecosystem development. Clarifying spatial heterogeneity in mitigating ES trade-offs between natural forests (NF) and planted forests (PF) (PF refer to forests established through planting or deliberate seeding, including ecological restoration forests, and shelter forests) under climate change, and differences in dominant factor regulation, remains urgent. This study focused on China's NF and PF, with carbon storage (CS) and habitat quality (HQ) as the target ESs. Climate variables were considered indicators of natural environmental conditions, and population density was used as a proxy for human activity. Utilizing a MaxEnt_XGBoost_SHAP model framework, we identified trade-off mitigation zones and optimal thresholds, analyzed the differential nonlinear responses of forest types to dominant factors, and explored effective pathways for mitigating forest ES trade-offs. The results indicated that: (1) The CS–HQ trade-off intensity decreased in NFs but increased in PF. (2) High-level CS was mainly distributed in the southern coastal regions, whereas high-level HQ was concentrated in Southwest China for NF and Southeast China for PF. (3) CS–HQ trade-off mitigation zones in NF were primarily located around the Sichuan Basin, where the optimal threshold range for CS increased significantly, while that for HQ decreased. In PF, mitigation zones were mainly distributed in southern China, with significant declines in the optimal threshold ranges for both CS and HQ. (4) The overall response intensity of environmental variables was higher in NFs than in PF. Environmental variables associated with HQ exhibited greater explanatory contributions in NF, whereas CS-related variables contributed more substantially in PF. From a forest management perspective, conservation of HQ should be prioritized in NF while maintaining carbon sequestration capacity. For PF, mixed-species PF and close-to-nature management should be implemented to synergistically enhance CS and habitat functions. This study provides a methodological framework and decision-making support for identifying the differentiated roles of NF and PF in mitigating ES trade-offs and promoting sustainable ecosystem development.