Comparisons of different regeneration approaches on soil respiration of Chamaecyparis obtusa planted in pine wilt disease-disturbed stands

Abstract

Changes in the abiotic and biotic factors created by forest regeneration can have a major influence on soil respiration, which is an important component of the forest carbon (C) cycle. This study was performed to determine the soil respiration rates caused by regeneration approaches in Chamaecyparis obtusa planted in pine wilt disease (PWD)-disturbed stands in South Korea. In 2007, four-year-old C. obtusa seedlings were planted with two regeneration approaches, clearcutting (CS) of infected pine trees or underplanting following selective cutting (DS) of infected pine trees in disturbed pine stands. Soil respiration rates were assessed in two regeneration approaches and an undisturbed pine stand (NS) for two years. The mean soil respiration rates were significantly lower in the DS (1.07 mu mol m(-2) s(-1)) treatment than in the NS (1.87 mu mol m(-2) s(-1)) treatment, whereas there was no significant difference between the CS (1.44 mu mol m(-2) s(-1)) treatment and the NS or DS treatment. The three treatments showed exponential relationships between soil respiration rates and soil temperature (R-2 = 0.57-0.81). The annual soil respiration rates were significantly higher in the CS (6.49 Mg C ha(-1) year(-1)) treatment than in the DS (3.98 Mg C ha(-1) year(-1)) treatment. The Q(10) values were lowest in the DS (2.00-2.03) treatment, followed by the CS (2.23-2.62) and NS (2.74-3.07) treatments. These results reveal that DS approaches in PWD-disturbed stands are one for the critical drivers of reducing annual soil respiration rates.