Clear‐cutting and slash burning effects on soil CO2 efflux partitioning in Chinese fir and evergreen broadleaved forests in subtropical China

Abstract

AbstractClear‐cutting (CC) and slash burning (SB) are common silvicultural practices in subtropical China, yet the time‐course response of soil CO2 efflux components to such disturbance is not well understood. This study examined the effects of CC and SB on soil CO2 efflux components in a Cunninghamia lanceolata (Lamb.) Hook (Chinese fir, CF) plantation and a secondary evergreen broadleaved forest (BF) located in Fujian Province, southeastern China. Aboveground litter removal and root trenching were used to estimate CO2 fluxes from soil organic matter decomposition (RSOM), litter decomposition (RL), and autotrophic respiration by roots and mycorrhizae (RR). These components were measured 5–7 times per month from 18 October 2001 to 25 December 2003 using soda lime absorption. We found that RR, RL and RSOM were initially higher in CC and SB plots than controls in both forests, but these three component fluxes in disturbed plots all fell below those of the control 5–20 months after the disturbance. Also, Q10 values of these components decreased following disturbance. The annual flux of each respiration component was greater under BF than CF. The contribution of RR to soil CO2 efflux in the control plots averaged 35% in CF and 46% in BF. RSOM was the dominant component of soil CO2 efflux in CC and SB plots, accounting for over 50%. Our results highlight the importance of temporal trends of the component fluxes following disturbance and contribute to a broader understanding of forest management effects on the soil C cycle.