Host: The Japanese Forestry Society
We examined occurrence trends of tree species in sugi plantations by comparison with those in natural forests in the warm-temperate region. Of the total 167 species occurred on 348 study plots (181 plantations and 167 natural forests), 96 and 64 species had biased occurrence in natural forests and plantations, respectively. The latter consisted of less numbers of evergreen trees and shrubs, which was thought to be the climax or late-successional species of the region. There were no clear difference in the proportion of seed dispersal types between the two occurrence type. By using a logistic regression analysis, 73 species were given significant models. Of these 73species, 23 species were detected to have a dependence of occurrence on stand age. The species which had dependence on the distance from the natural forests and better light environment were only 10 and 13 species respectively. Eleven species showed their occurrences depending on the time after the latest thinning. These results suggested that most plantations were likely to lack the 'natural forest type' species, and that it would be difficult to improve this lack by thinning practices or extending the rotation of logging.
