抄録
Forty-five secondary oak forests were studied phytosociologically in Tama district in the western suburb of Tokyo City to clarify the influences of urbanization on their herb-layer species composition. Principal component analysis was applied to the presence-absence data of 74 herb-layer species. The first principal component (PC1) differed little between the stands, and they could be reasonably ordinated by the second (PC2) and the third (PC3) principal components. PC2 was positively correlated with the percentage of residential area around a stand, while PC3 showed negative correlation with the abundance of phanerophytes in the herb-layer. These correlation analyses and the scores for PC2 and PC3 of respective species suggested that PC2 should be identified with the change due to urbanization and PC3 with the intensity of human disturbance. Some suggestions were made on the technical principle of forest conservation in suburban areas.
