Estimation of carbon storage, carbon inputs, and soil CO2 efflux of alder plantations on granite soil in central Korea: comparison with Japanese larch plantation

Alder is a typical species used for forest rehabilitation after disturbances because of its N2-fixing activities through microbes. To investigate forest dynamics of the carbon budget, we determined the aboveground and soil carbon content, carbon input by litterfall to belowground, and soil CO2 efflux over 2 years in 38-year-old alder plantations in central Korea. The estimated aboveground carbon storage and increment were 47.39 Mg C ha−1 and 2.17 Mg C ha−1 year−1. Carbon storage in the organic layer and in mineral soil in the topsoil to 30 cm depth were, respectively, 3.21 and 66.85 Mg C ha−1. Annual carbon input by leaves and total litter in the study stand were, respectively, 1.78 and 2.68 Mg C ha−1 year−1. The aboveground carbon increment at this stand was similar to the annual carbon inputs by total litterfall. The diurnal pattern of soil CO2 efflux was significantly different in May, August, and October, typically varying approximately twofold throughout the course of a day. In the seasonally observed pattern, soil CO2 efflux varied strongly with soil temperature; increasing trends were evident during the early growing season, with sustained high rates from mid May through late October. Soil CO2 efflux was related exponentially to soil temperature (R2 = 0.85, P < 0.0001), but not to soil water content. The Q10 value for this plantation was 3.8, and annual soil respiration was estimated at 10.2 Mg C ha−1 year−1.