2006 Volume 23 Issue 2 Pages 119-136
Species composition and distribution of evergreen conifer plantations dominated by Cryptomeria japonica, Chamaecyparis obtusa and/or Chamaecyparis pisifera was studied by phytosociological method in the eastern part of the Kanto region, central Japan. The vegetation was divided into four communities: Cryptomeria japonica-Microlepia marginata community (CM), Cryptomeria japonica-Houttuynia cordata community (CH), Cryptomeria japonica-Athyrium yokoscense community (CA) and Cryptomeria japonica-Fraxinus lanuginosa f. serrata community (CF). The distribution of each community was influenced by air temperature. Warmth index (WI) of the distribution area of CM was higher than 120℃・month. CH was distributed in the area where WI was lower than 120℃・month and mean temperature of the coldest month (MTCM) was higher than 2℃. CA was distributed in the area where WI was lower than 100℃・month and MTCM was lower than 2℃. CF was distributed in the area where WI was lower than 90℃・month. The distribution area of the community in this study nearly corresponded to the distribution area of association of natural forest in the Kanto region. Comparing the life form in each community, evergreen woody plants showed a high component ratio in CM and CH. On the other hand, the component ratio of deciduous woody plants had an increasing tendency in the following communities: CM, CH, CA and CF. Compared with the component ratio of character and differential species in the other vegetation units, the character and differential species in Camellietea japonicae and the lower units of the class showed a high component ratio in CM and CH. On the other hand, the character and differential species in Fagetea crenatae showed a high component ratio in CA and CF. Furthermore, component ratio of the character and differential species in Rosetea multiflorae and Artemisietea principis showed a 15-30% ratio in each community. Therefore, plantation vegetation involved species of mantle communities, and the establishment of these species may be influenced by forest management.
