Abstract
To clarify the size distribution characteristics of trees in old-growth Japanese cedar plantations, we conducted a multi-po int survey in Gujo City, Gifu Prefecture, Japan. The old-growth stands (≥ 80 years) comprised around 1000 m3 stand volume. The relationships between tree crowding indices (relative yield index), indices of size heterogeneity (coefficient of variation), and size asymmetry (skewness) revealed that the size heterogeneity of diameter and stem volume was significantly higher in old-growth stands than in mature stands (40–80 years) under identical crowding conditions. In most of the old-growth stands, the skewness of diameter did not significantly differ from zero indicating a normal distribution, whereas the skewness of stem volume was significantly positive, indicating a positively skewed distribution with its tail on the right side. These results suggest that the old-growth Japanese cedar plantations in Gujo City are characterized by relatively high stand volumes, high size heterogeneity and high size asymmetry. The results also suggest that individual tree management is important in old-growth stands with lower tree density and large disparity in tree size.
