The species composition of evergreen broad-leaved forests on Hachijo-jima Island was studied. Hachijo-jima Island is one of the Izu islands, and is composed of two volcanoes of different ages : Mt. Hachijo-Fuji, a Holocene volcano, and Mt. Mihara, a Pleistocene volcano. The forest vegetation was examined by phytosociological method. The vegetation was divided into three associations (Daphniphyllo-Trochodendretum aralioides Ohba 1971, Carici-Castanopsietum sieboldii Ohba 1971 : CC and Euonymo-Pittosporetum tobira Miyawaki et al. 1971 : EP) and one community (Persea thunbergii-Prunus speciosa community: PP), and the Daphniphyllo-Trochodendretum aralioides was divided into two lower units (Irex crenata van hachijoensis lower unit : DTI and Sasamorpha borealis var. viridescens lower unit : DTS). The distributions of the DTI and PP were restricted to Mt. Hachijo-Fuji. The DTI was distributed above 430 meters a.s.l., and the PP was distributed below 550 meters a.s.l. In contrast, the distribution of the DTS was restricted to Mt. Mihara (above 490 meters a.s.l.), and the CC was distributed mostly on Mt. Mihara (below 540 meters a.s.l.). The EP was found along the seashore of both volcanoes. The distribution patterns of these forest communities was related to altitude and age of the volcanoes. Long-term succession on Hachijo-jima Island from the DTI to the DTS at higher altitude, and from the PP to the CC at lower altitude were suggested.

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Quercus serrata communities are summer-green broad-leaved forests, which are composed of dominant Quercus serrata, Q. variabilis and Q. acutissima and other hardwoods. These coppice communities are mostly secondary forests, however they occur also in natural habitats. Floristic composition and distribution of Quercus serrata communities of Honshu, Shikoku and Kyushu in Japan were investigated phytosociologically, and nine associations were classified. These nine associations occur from northern Honshu to southern Kyushu, and were divided into five distribution areas as follows : the coastal area, the southwest Japan area, the northeast Japan area, the central Japan area and the Sea-of-Japan-side area. In the vertical distribution, Q. serrata communities are divided into two distribution types. One is the Camellietea japonicae region below about 800m a.s.l., and the other is from the Cammeliatea japonicae region to the lower part of the Fagetea crenatae region below 1350m. These nine associations belong to Carpino - Quercion serratae, Quercetalia serrato-grosseserratae and Fagetea crenatae. In the species combination, Quercus serrata communities in Japan have many common or relational species to those forests in China and Korea, and have a close relationship to the vegetation geography.

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The distributions of three dominant species, Fraxinus spaethiana, Pterocarya rhoifolia and Cercidiphyllum japonicum, were investigated in relation to the species composition in a riparian forest in Chichibu, central Japan. This riparian forest varied from V-shaped valley to sedimentary basin of earth and rocks topographically, and was classified into a Chrysosplenieto-Fraxinetum spaethianae association phytosociologically. This association was further classified into three community units each with characteristic topography. The Acer shirasawanum sub-association was distributed in the sedimentary basin of earth and rocks, Deinanthe bifida sub-association Carex morrowii variant in slopes and sub-ridges of V-shaped valley, and D. bifida sub-association typical variant in taluses and the bottom of the V-shaped valley. The dominant tree species F. spaethiana was distributed at all sites, especially in a stable location such as a sedimentary basin of earth and rocks. On the other hand, P. rhoifolia was distributed in the alluvial fan area and sedimentary basin of earth and rocks, and C. japonicum in V-shaped valley. Therefore F. spaethiana was dominant in all areas of the Chrysosplenieto-Fraxinetum spaethianae association. On the other hand, the distribution of P. rhoifolia was roughly identical to that of the A. shirasawanum sub-association, and C. japonicum was distributed in the area of D. bifida sub-association including both C. morrowii and typical variants. This distribution of the dominant species would depend on each regeneration trait adapted to the disturbance in the riparian area. It can be concluded that each vegetation unit reflects the location suitable for regeneration of these dominant species in the riparian forest.

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The effects of geology and landforms on the distribution of Fagus crenata were investigated in a forest ecotone between subalpine and montane forest zones. The distribution of F. crenata trees was mapped by field surveys and aerial-photo interpretation in the Kamikochi Valley in the upriver regions of the Azusa River Basin, central Japan. Most F. crenata trees were found on steep, dissected slopes within areas of late Cretaceous to early Paleocene granitic rocks, and at the margin where Mesozoic sedimentary rocks contacted granitic rocks. The erosion front that has developed on mountain slopes since the Holocene probably controls the upper limits of F. crenata. Landslides on dissected slopes appear to be important for F. crenata to become established in the area of distributional limit. They may improve edaphic and light conditions on the forest floor.

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The phytosociology of a Suaeda malacosperma community in Japan and distribution of four species belonging to the genera Suaeda (Chenopodiaceae) ; S. asparagoides (Miq.) Makino, S. maritima (L.) Dumort, 5. japonica Makino and S. malacosperma Hara in western Kyushu, were studied. These species predominantly grow on salt marsh, except S. asparagoides which grows at the high tide line on sandy or shingly beach. In western Kyushu, S. asparagoides was chiefly found on islands, and was mostly frequent in the northern island of Tsushima. S. maritima was widely distributed, but S. japonica was restricted to Ariake Bay area. S. malacosperma was distributed in Tsushima, Kami-goto and Sasebo City in Nagasaki Prefecture and Ariake Bay area in Saga Prefecture. S. japonica and S. malacosperma were found together at some localities in Ariake Bay area and S. maritima and S. malcosperma were found together at a locality in Tsushima and Kami-goto. However, S. maritima and S. japonica were never found at the same locality. S. malacosprma was an endemic species distributed from Aichi Prefecture through the Seto Inland Sea area to western Kyushu. The range extended in a restricted area from north to south, and widely from east to west. The easternmost locality was in Atsumi Peninsula of Aichi Prefecture and the westernmost locality was in Wakamatsu-cho of Nagasaki Prefecture. Plants of this species already became extinct in Okayama, Fukuoka, Kumamoto and Kagoshima Prefectures, and is endangered in other prefectures. S. malacosperma community syntaxonomically classified as a new association Suaedetum malacospermae with three subassociations.

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The floristic composition and stand structure of lowland forests were studied in the Ishikari Lowland, central Hokkaido, northern Japan. In 30 plots, diameters at breast height (i.e., DBH) of trees ≧5cm were measured, and phytosociological measurements were carried out on the vascular plants. Phytosociological classification methods were applied to 30 vegetation samples from the plots, and additional 10 samples obtained from the literature. Lowland forests were classified into the following two communities: the Ulmus japonica-Syringa reticulata community, and the Fraxinus mandshurica van japonica-Lysichiton camtschatcense community (includes 4 under units and 2 stand groups). These two communities were comparable to Syringo-Fraxinetum mandshuricae and Dryopterido monticolae-Fraxinus mandshuricae japonicae, respectively. Differences in floristic composition among plots were clearly shown by the first axis of detrended component analysis (DCA). Correlations between scores of the first axis and climatic features clarified that the sites of the F. mandshurica van japonica-L. camtschatcense community were warmer, and were deeper in snow cover than those of the U. japonica-S. reticulata community. Thus, the difference in floristic composition between two communities was probably caused by climatic conditions. On the other hand, equitability of tree dominance (relative basal area) was lower in the F. mandshurica van japonica-L. camtschatcense community than in the U. japonica-S. reticulata community. Since there was a difference in soil type between the two communities, it seems that not only climatic features but edaphic conditions were responsible for the difference in stand structure between two communities.

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