Ecosystem respiration and tree growth influenced by thinning in a red pine forest in southern Korea

Abstract

This study was conducted to determine the effect of thinning on the ecosystem respiration in a red pine forest in southern Korea. We measured the ecosystem respiration and its component respirations from soil, stem, leaf, and coarse woody debris (CWD) in thinned and control stands during 2010. The forest was thinned in October 2009. The total respiration was 8.37 and 8.82 Mg C ha−1 year−1 in the thinned and control stands, respectively. Estimated annual soil, leaf, stem, and CWD respirations in the thinned stand were 5.55, 1.41, 0.90, and 0.51 Mg C ha−1 year−1, accounting for 66, 17, 11, and 6%, respectively. Estimated annual soil, leaf, and stem respirations in the control stand were 5.54, 2.09, and 1.19 Mg C ha−1 year−1, accounting for 63, 24, and 13%, respectively. The organic C storage in tree biomass (149.24 vs. 198.61 Mg C ha−1), input from litterfall (6.79 vs. 7.92 Mg dw ha−1 year−1) and total tree biomass increment (7.67 vs. 9.28 Mg C ha−1 year−1) were all significantly lower (P < 0.05) in the thinned stand than in the control stand. However, the individual tree increment was higher in the thinned stand than in the control stand (9.35 vs. 8.24 kg C year−1). Organic C output through the loss rate of litter mass was significantly higher (55 vs. 50%, P < 0.05) in the thinned stand than in the control stand. These results indicate that ecosystem respiration was slightly increased by thinning, whereas tree biomass C dynamics, and organic C input and output through litter production and decomposition were decreased by thinning. Further long-term study and analyses will be required to define overall C cycling in red pine forests.