Impact of thinning on carbon storage of dead organic matter across larch and oak stands in South Korea

Abstract

Dead organic matter is important in carbon (C) sequestration because it accounts for a significant proportion of forest C storage. As thinning could alter the C storage of dead organic matter, this study aimed to assess the effect of thinning on the C storage of dead organic matter including the forest floor, mineral soil at a depth of 0-30 cm, and coarse woody debris in larch and oak forests in South Korea. Differing intensities of thinning were applied to four larch and four oak stands, and the C storage of dead organic matter in thinned and control plots was compared three years after thinning. The effect sizes were estimated based on Hedges’ d to measure the influence of thinning. Total C storage of dead organic matter tended to be higher in the thinned plots (larch: 82.45 Mg C ha-1 and oak: 82.56 Mg C ha-1) than in the control plots (larch: 72.07 Mg C ha-1 and oak: 74.79 Mg C ha-1). However, estimation of effect size found that the cumulative effect size was not significant for the C storage of the forest floor, mineral soil, coarse woody debris, and dead organic matter. Only a few of the individual treatments exhibited significant effect sizes for mineral soil C storage in two larch stands and coarse woody debris C storage in two oak stands. The results indicated that the applied thinning treatments might have no consistently significant impact on the C storage of dead organic matter in the larch and oak stands after three years, though thinning may have had an idiosyncratic influence on the C storage of dead organic matter in a few of the study stands.