Carbon Stock Differentials Associated with Private Forest Land-Use Designation in South Korea: Evidence from Propensity Score Matching

Private forest land-use designations can contribute to climate mitigation; however, their carbon benefits are difficult to estimate because protected and less strictly regulated forest lands often differ in site and environmental conditions. Evidence on whether designation-associated carbon differences vary with forest structure is also limited. This study evaluated carbon stock differentials between protected areas in private forests (PA) and matched semi-conservation mountainous districts (SCA) in South Korea using the InVEST Carbon Storage and Sequestration model. Propensity score matching was used to improve comparability, followed by average treatment effect on the treated (ATT) estimation and regression analysis of the matched sample. Alternative matching and regression specifications were examined as robustness checks. The mean carbon stock was 4.97 Mg C ha⁻¹ higher in PAs than in comparable SCAs (95% CI: 4.45–5.49, p < 0.001). The PA-SCA difference varied by forest structure: it was greater in broad-leaved forests than in coniferous forests, showed a nonlinear pattern across canopy density classes, and declined with increasing age class. These findings indicate that carbon stock differences associated with private forest land-use designation are structurally heterogeneous. While they should be interpreted as cross-sectional associations, they provide evidence for differentiated land-management, compensation, and conservation prioritization strategies.