Forest stand dynamics of a plantation of Cryptomeria japonica (ca. 37 years old) colonized by native trees were investigated in a 0.84-ha plot in Ohshuku District from 2000 to 2008. The rate of decrease in stem density increased and the growth rate of the basal area decreased with time. The recruitment rate of stem density was a modest 4.3 ha^-1 yr^-1 during the eight years. These results suggested that the stand was in the stem exclution stage under strong competition for light. The shape of the stem diameter distribution was unimodal for C. japonica trees and reverse-J for native trees in 2000, but shifted to bimodal for both C. japonica and native trees in 2008. The mortality rate per diameter class was higher in the 4- and 6-cm diameter class than in the larger classes for both C. japonica and native trees. The diameter increment was positively correlated with the initial stem diameter for both C. japonica and native trees. These results indicated that size hierarchies in the stand developed with time. The relative basal area of native trees was 16% and remained constant during the eight years. This tendency resulted from the vigorous growth of native trees under strong competition from overtopped C. japonica trees.

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[in Japanese]

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