其他摘要：Individual tree-based management in natural forests becomes more important in managing old growth Japanese cedar (Cryptomeria japonica) stands because of the decline of timber resources from natural forests. We set a 1-ha study plot in Nibuna-Mizusawa Forest Reserve, Akita, northern Japan, which mainly consisted of about 300-year-old Japanese cedars. The individual growth of tree diameter at breast height (DBH) was calculated using censuses in 2006 and 2010. The effects of soil depth (summed value of A and AB layers) , soil moisture, light conditions of the tree crown (relative concavity and convexity levels against the surrounding) , and neighborhood competition (indicated by sum of basal area of neighboring trees around each tree) were examined by generalized linear models. The mean DBH growth rate was 0.18±0.21 cm/year. The DBH growth rate decreased with increasing soil moisture within most values for soil moisture we observed. The tendency in our results suggested that some cedars grew worse in damp soils, although other unknown soil factors associated with soil moisture (e.g. nutrients) should also been examined. The effect of the neighboring trees was marginally negative, suggesting competition for soil nutrient and/or light. The processes leading to the presented patterns were discussed.
