Soil respiration in a subtropical forest of southwestern China: Components, patterns and controls

Partitioning the components of soil respiration is crucial to understand and model carbon cycling in forest ecosystems. In this study, total soil respiration ( R S ), autotrophic respiration ( R A ), heterotrophic respiration ( R H ), litter respiration ( R L ), litterfall input and environmental factors were synchronously monitored for 2 years in a subtropical Michelia wilsonii forest of southwestern China. R H rates were often higher than R A rates during the two years except for the middle growing season (from July to September). The mean rate of R s, R A , R H and R L was 1.94 μmol m -1 s -1 , 0.85 μmol m -1 s -1 , 1.09 μmol m -1 s -1 and 0.65 μmol m -1 s -1 , respectively, during the 2-year experiment. Annual CO 2 emission derived from R A , R H and R L was 3.26 Mg C ha -1 a -1 , 4.67 Mg C ha -1 a -1 and 2.61 Mg C ha -1 a -1 , respectively, which accounted for 41.4%, 58.6% and 32.9% of R S . Over the experimental period, the ratio of R A / R S increased with soil temperature but the opposite was true for R H / R S and R L / R S . The Q 10 value was 2.01, 4.01, 1.34 and 1.30, respectively, for R S , R A , R H and R L . Path analysis indicated that environmental variables and litterfall production together explained 82.0%, 86.8%, 42.9% and 34.7% variations of monthly fluxes of R S , R A , R H and R L , respectively. Taken together, our results highlight the differential responses of the components of R S to environmental variables.