The relationship between community types and landforms of Abies homolepis forests was investigated along the Azusa River around Kamikochi, Central Japan. Abies homolepis is dominant in some forests on the depositional landforms around the Azusa River in the upper cool temperate zone. Two communities were classified by the phytosociological method : Tsuga diversifolia-Abies homolepis community and Ulmus davidiana var. japonica-Abies homolepis community. The former was differentiated by Tsuga diversifolia, Oxalis acetosella, Euonymus melananthus, E. oxyphyllus and others, and classified into Cornus canadensis, typical, Cacalia hastata var. farfaraefolia and Aesculus turbinata under units. Some of the differential species belonged to the class Vaccinio-Piceetea. The latter community was differentiated by mesic species that belonged to Fraxino-Ulmetalia : Pachysandra terminalis, Cacalia hastata var. ramosa, Mitella pauciflora etc. This community was classified into Sasa senanensis and Mitella pauciflora under units. These two communities were compared with Abies homolepis communities around Mt. Yatsugatake and Mt. Fuji by the synthetic table. The results showed that Abies homolepis communities in Kamikochi had many differential species, and many of them were included in Fraxino-Ulmetalia. The environmental factors (the size and lithology of surface materials, landforms, slope degree and slope aspects) were analyzed by the Quantification-III method. The results showed that Tsuga diversifolia-Abies homolepis community mostly occurs on the alluvial cones and on the valley plains in the tributaries. In contrast, Ulmus davidiana var. japonica-Abies homolepis community was restricted to the floodplains of the main stream which were mainly composed of fine sand. The differences between Cornus canadensis and Cacalia hastata var. farfaraefolia under units are based on the size and lithology of surface materials.

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Effect of Robinia pseudoacacia L. plantation on vegetation and site condition under semi-arid and cold climate was investigated in Loess Hilly Region, China. Vegetation and site condition were compared among 4 land-use types, a R. pseudoacacia plantation which was protected from felling and pasturing for 22 years, a Sophora viciifolia Hance dominant scrub which was regenerated naturally from pasture for 22 years, a pasture with 10 sheep per hectare, and a crop field. Number of plant species, plant diversity was higher in the R. pseudoacacia plantation, compared with other land-use type. Biomass increment estimated by community structure was bigger in the R. pseudoacacia plantation than in the 5. viciifolia dominant scrub. Properties of soil were changed most greatly by R. pseudoacacia plantation. In particular, organic matter accumulated and water content increased in surface soil of the R. pseudoacacia plantation. Amounts of soil and water loss were smallest in the R. pseudoacacia. plantation. Thus the reforestation of the Loess Hilly Region by R. pseudoacacia was effective to improve plant biomass, plant diversity and soil condition.

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The distribution and ecology of the semi-mangrove, Hibiscus hamabo dominant community was studied in western Kyushu, Japan. Attention was paid to the community size and coastal landforms of the habitat in which it was growing. A distribution map showing both localities and size of each community stand was drawn. The H. hamabo community was widely and frequently distributed in western Kyushu. However, most localities contained fragmented or small communities. The medium-sized communities were scattered and the large were restricted in location. The most frequent coastal landforms of their habitats were inlets followed by estuaries, lagoons and sea-relic lakes. The communities whose population is more than 10 individuals were chiefly found on the lagoon and the estuary sites including downstream of rivers. The large communities were also developed only on lagoons and estuaries. The habitat of the community is normally situated on the high tide water level, but was somewhat higher on the gulf coast and lower in estuaries than the high water level. The community was phytosociologically identified as the association Hibiscetum hamabo (Nakanishi 1979) and was divided into two subassocations by the species composition and stand conditions. The one was the typical subassociation and the other was the Vitex rotundifolia subassociation. The former was composed of only H. hamabo in the shrub layer and was occasionally invaded by salt marsh elements in the herb layer. The latter is differentiated by the occurrences of the shingle beach elements and was only developed on the shore of the gulf coast. For conservation of the H. hamabo community, it is important to keep the natural conditions of lagoons and estuaries.

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[in Japanese]

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