Changes in Soil CO₂ Flux along a Forest Fire Chronosequence on the East Coast of Korea

Abstract

This study aimed to analyze long-term changes in soil CO2 flux (Rsoil, soil respiration) using a chronosequence approach in forests affected by forest fires on the east coast of Korea. Rsoil was measured seasonally along with soil temperature and moisture to assess its response to environmental variation. Additionally, soil physicochemical properties and fine root (≤2 mm) biomass were analyzed to investigate their correlations with Rsoil. Total carbon (TC) and nitrogen (TN) concentration in soil, and fine root biomass were initially low, peaked during the mid-recovery stage, and then tended to stabilize, whereas soil permeability, sand, silt, and clay contents exhibited distinct patterns. Rsoil increased exponentially with soil temperature, showing higher coefficient of determination (R2) in late recovery stage (0.67) and unburned stands (0.72) than in early stage (0.30). Temperature sensitivity (Q10) of Rsoil showed no significant differences among recovery stages, however the Q10 values exhibited relatively low in early stage compared to other stages. The relationship between soil moisture and Rsoil was weak overall, except in the unburned (R2=0.27, p＜0.01). Rsoil at 20°C (R20, µmol CO2 m-2 s-1) increased with the duration of recovery, with values of 2.38±0.34, 4.11±0.25, 3.14±0.13, and 4.23±0.38 in early-, mid-, late stages, and unburned, respectively. R20 was positively correlated with soil permeability, TC, TN, and fine root biomass (p＜0.05). These findings highlight the importance of Rsoil as an indicator of soil recovery, contribute to the assessment of post-fire soils and the understanding of soil carbon dynamics.