Stand‑Level Soil Carbon Turnover Dynamics Among Adjacent Temperate Plantation Stands in South Korea

Understanding the mechanisms of soil carbon turnover is critical for interpreting soil carbon stability, yet these processes remain difficult to distangle due to environmental heterogeneity among forest sites. This study investigated carbon turnover dynamics among adjacent experimental plantation stands established with four species (Pinus strobus, Quercus aliena, Q. serrata, and Carpinus laxiflora) in a temperate forest of South Korea. Because the stands were established during the same period under similar environmental conditions, this setting allows a comparative assessment of carbon cycling processes across plantation stands while minimizing environmental heterogeneity. Soil carbon turnover was evaluated using complementary indices, including the respiration-to-carbon input ratio (RIR), soil carbon turnover time (τsoil), and the proportion of soil C relative to total C (PSI). Clear differences in soil carbon turnover dynamics were observed among the plantation stands. Variation in soil CO2 efflux contributed strongly to these differences, whereas carbon input by litterfall and soil physicochemical properties showed comparatively smaller contributions. These findings suggest that soil carbon turnover dynamics among adjacent plantation stands are strongly associated with variation in respiratory carbon losses under similar environmental conditions. This study provides a stand‑level comparative framework for interpreting soil carbon turnover dynamics in temperate plantation forests.