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Coarse woody debris (CWD) mass dynamics in three temperate natural forests, dominated by Quercus mongolica, Abies holophylla, and Pinus densiflora, were studied for 5 to 8 years in a Korea National Long-Term Ecological Research (KNLTER) site located in Mt. Jumbong, Korea. CWD mass (Mg/ha), input rate of CWD mass (Mg ha-1 y-1), and decay rate constant (1/y) were 20.6, 1.20, and 0.058 for Q. mongolica forest, 12.2, 0.44, 0.106 for A. holophylla forest, and 5.0, 0.00, and 0.086 for P. densiflora forest, respectively. CWD mass was classified into species, types (log, snag, and stump), and decay classes (I-V). The proportion of logs was higher than that of the other CWD types in Q. mongolica forest because of wind-related mortality, whereas the proportion of logs was similar to the proportion of snags in A. holophylla forest and P. densiflora forest. CWD mass, input rate, decay rate, and distribution reflected the status of forest regeneration and succession for three forests. Mass dynamics were affected interactively by a variety of factors including species, microclimate, and topography, but these effects were hardly distinguishable in this study because of the limited number of comparable sites and pieces of CWD. Thus, further studies will require data regarding long-term microclimate and CWD mass dynamics in a variety of forest types, which could represent diverse environmental factors.

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This study was conducted to examine the soil aggregate distributions and their relationship with microbial biomass carbon (C) concentration and soil C in Pinus rigida and Larix kaempferi plantations. Soil samples of 0-10 cm, 10-20 cm, and 20-30 cm depth were collected and the microbial biomass C concentration was measured. The soils were then classified into four aggregate size classes by wet-sieving procedure [large macroaggregate (42000 mm), small macroaggregate (250-2000 mm), microaggregate (53-250 mm), and silt-plus-clay (553 mm)] and the C content of each aggregate size class was analyzed. The L. kaempferi plantation contained more macroaggregate over 250 mm than the P. rigida plantation did. The mean weight diameter (MWD) of the soil aggregate up to 30 cm depth was 1.26 mm and 1.45 mm in the P. rigida and L. kaempferi plantations, respectively, and it decreased with soil depth. The microbial biomass C concentration up to 30 cm depth was 510 mg C g soil 71 for the P. rigida plantation and 764 mg C g soil 71 for the L. kaempferi plantation, and it was greatest in the surface soil in both plantations. The mean soil C concentration up to 30 cm depth was 2.00% for the P. rigida plantation and 2.88% for the L. kaempferi plantation. In both plantations, the soil C concentration was higher in the surface soil than in the deep soil. However, there was no significant difference of C concentration among the soil aggregate size classes. The soil C content up to 30 cm depth in the P. rigida and L. kaempferi plantations were 47.69 Mg ha 71 and 61.49 Mg ha 71 , respectively, and were also higher in the surface soil than in the deep soil. In both plantations, macroaggregate contained more C content than microaggregate did. The microbial biomass C and soil C concentrations were significantly higher (P 5 0.05) in the L. kaempferi plantation than in the P. rigida plantation due to the effect of species difference. The MWD and C content tended to be greater in the L. kaempferi plantation than in the P. rigida plantation, but the differences were not significant. In this study, the soil aggregate size, microbial biomass C and soil C concentrations were positively correlated with one another.

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