Research on the Impact and Mechanism of Forest Ecological Security on Forest Carbon Sinks: Evidence from 31 Provinces in China

Amid the accelerating global pursuit of carbon neutrality, the regulatory role of forest ecological security in carbon sink function has emerged as a critical issue in achieving climate goals. This study developed a forest ecological security evaluation index system based on the Driving Force–Pressure–State–Impact–Response–Management (DPSIRM) framework. The forest ecological security comprehensive index for 31 Chinese provinces from 2007 to 2022 was calculated using the entropy weight method, and forest carbon sinks were estimated through the volume expansion method. Spatial econometric models and a mediation effect model were employed to empirically examine the impact of forest ecological security on forest carbon sinks and their underlying mechanisms. The results indicated the following: (1) Improvements in forest ecological security exerted significant positive direct and spatial spillover effects on forest carbon sinks. (2) The enhancing effect of forest ecological security on carbon sinks was significant in western regions, resource-based provinces, and economically underdeveloped areas. (3) Forest area transition and forest age structure transition served as key mediators in the relationship between forest ecological security and carbon sinks. In contrast, the mediating effects of forest species structure transition and forest origin structure transition were not significant, likely constrained by long-term ecological thresholds and socioeconomic inertia.