Estimation of soil respiration using automated chamber systems in an oak (Quercus mongolica) forest at the Nam-San site in Seoul, Korea

Soil respiration (R-soil) is the largest component of ecosystem respiration produced by the autotrophic and heterotrophic respirations. Its variability on multiple time scales strongly depends on environmental variables such as temperature and moisture. To investigate the temporal variations of R-soil in a cool-temperate oak (Quercus mongolica) forest at the Nam-San site in Seoul, Korea, continuous measurements of R-soil using the automated chamber systems, air and soil temperatures and soil moisture are made for the period from April 2010 to March 2011. The observed data indicate that the R-soil shows a remarkable seasonal variation in accordance with temperatures with high in summer and low in winter. The R-soil is found to be strongly correlated with soil temperature (T-s) at the 5 cm depth throughout the year. However, the high fluctuation of R-soil is found to be related with soil moisture content (M-s) during the forest growing season. The estimated annual Q(10) value using the 1.5 m-high air temperature is found to be 2.4 that is comparable with other studies in temperate forest ecosystems. The optimal regression equation of R-soil with the T-s at 5 cm depth and the M-s at 15 cm depth is found to be R-soil = 124.3 exp (0.097T(s)) - 55.3 (M-s)(2) + 2931.9 (M-s) - 38516 for T-s >= 0 degrees C and R-soil = 0 for T-s<0 degrees C with r(2) = 0.97, P<0.01, suggesting the importance of T-s and M-s for R-soil. The annual total soil respiration estimated by the optimal regression equation is found to be 1264 g C m(-2) with a maximum of 685 g C m(-2) in the summer season and a minimum of 33 g C m(-2) in the winter season. The present study can be implemented for the determination of the carbon balance of a cool-temperate Q mongolica forest with the provision of photosynthesis. (C) 2011 Elsevier B.V. All rights reserved.