[Trade-offs/Synergies of Ecosystem Services in the Xiaoxing'an Mountains Based on the InVEST Model]

The aim of this study was to understand and monitor the dynamic shifts in ecosystem services within the Xiaoxing'an Mountains Region， uncover the driving factors for these diverse ecosystem services， and offer a scientific foundation for devising effective regional management policies. Focusing on the Xiaoxing'an Mountains as the primary subject of study， this research employs the CASA and InVEST models to quantify five key ecosystem service functions： water conservation， soil conservation， habitat quality， carbon storage， and recreational tourism. The spatial overlay method is employed to analyze the spatiotemporal heterogeneity of the trade-off/synergy relationships among ecosystem services within the study area. Utilizing the optimal parameter-based geographic detector model， this study investigates the driving factors that influence ecosystem services. The results indicate that： ① Over time， water source conservation services in the study area saw an increase from 1990 to 2020， rising by 42%. The amount of soil conservation decreased by 4 million tons， and recreational tourism services were on a downward trend. The average net primary productivity （NPP） （in carbon units） was 754.03 g·（m²·a）^-1， exhibiting an initial increase followed by a decline. Habitat quality services remained largely unchanged and were generally in good condition. ② Overall， the ecosystem service relationships in the southeastern part of the study area were primarily characterized by high synergy， whereas those in the central and northwestern parts were primarily marked by weak trade-offs. Interactions between pairs of ecosystem services were predominantly synergistic， with each service enhancing the others. ③ Natural factors were the primary drivers influencing the ecosystem services and their interactions within the study area. In the water source conservation service， precipitation was the primary factor； in soil conservation， topographic relief was the primary factor； in habitat quality services， population density was the primary factor； in carbon storage， elevation was the primary factor； and in entertainment and tourism services， the interaction between precipitation， distance to the road， and annual average temperature had a significant impact. The results of this study help to grasp the main types of ecosystem services in the Xiaoxing'an Mountains Region， comprehend the spatiotemporal heterogeneity and driving factors of the distribution of ecosystem services， and in the future， devise differentiated functional optimization strategies in line with the characteristics of ecosystem service functions in different regions.