Community structure of secondary evergreen broad-leaved forests in the urban area of Kitakyushu City, western Japan

All stems taller than 2 m were investigated in eight isolated secondary evergreen broad-leaved forests in urban Kitakyushu City. Some community parameters, such as total basal area and density of stems, were similar among plots. Castanopsis-type forests and Lauraceae-type forests were classified by the physiognomy of the plots. Cluster analysis based on total basal area of each species belonging to each layer (canopy and understorey) also showed that the similarities among plots were very small except for three plots which had relatively similar distance values, although the results for the classification did not correspond with those classified by physiognomy. Some important components in old-growth evergreen broad-leaved forests, such as Camellia japonica and Cleyera japonica, are hardly able to maintain their populations in the study area. Lack of these species might not be attributed to fragmentation of the forests but to the past human disturbance regime in the area. The effect of fragmentation to species diversity for trees taller than 2 m in height was not clear in the urban area studied.