Spatiotemporal variation characteristics and their trade-offs and synergies of forest ecosystem services in Nanwan Reservoir Area, Henan Province of central China

Objective This study aims to reveal the spatiotemporal variations in forest ecosystem service disparities and their trade-offs and synergies, thereby providing a scientific basis for forest resource conservation and sustainable management.

Method This study, conducted in the Nanwan Reservoir Area of Xinyang City, Henan Province of central China as the study area, provides a comprehensive assessment of four forest ecosystem services (i.e., carbon sequestration, water conservation, soil retention, and habitat support) over the period from 2000 to 2020 using the InVEST and CASA models. Based on the spatiotemporal patterns, we further employed spatial overlay methods to explore the trade-offs and synergies among these four ecosystem services.

Result (1) The average annual carbon sequestration was 587.41 g/m², while the average annual water conservation, soil retention, and habitat quality index were 361.71 mm, 612.29 t/ha, and 0.9, respectively. (2) Temporally, carbon sequestration showed an overall increasing trend with fluctuations, whereas water conservation and soil retention initially declined before rising, and the habitat quality index exhibited a slight decreasing trend. Spatially, high-value ecosystem service areas were predominantly located in the western forested regions characterized by low mountains, whereas low-value areas were concentrated around downstream regions and surrounding water bodies. (3) Among the nine forest types, Quercus acutissima demonstrated the highest capacity for providing integrated ecosystem services. (4) The relationship among the four ecosystem services were characterized by high synergies and strong trade-offs, with synergistic areas increasing and trade-off regions decreasing over time. (5) High-synergy areas were predominantly found in Quercus acutissima forests, Pinus massoniana-Quercus acutissima mixed forests and bamboo forests, while trade-offs were commonly observed in Cunninghamia lanceolata and Pinus massoniana forests. Economic forests, such as chestnut forests and tea plantations, exhibited significant trade-offs, whereas interactions in shrubland and sparse woodlands were more heavily influenced by environmental conditions. (6) The primary driving factors of forest ecosystem services were identified as average annual precipitation, average annual temperature, normalized difference vegetation index and population density.

Conclusion This study highlights the differences in ecosystem service capabilities among various forest types and identifies key areas that require prioritized protection and restoration, which provides a scientific foundation for enhancing the comprehensive benefits of forests in the Nanwan Reservoir Area.