Large-scale residential development accompanied by intense landscape modification has been carried out since about 1960 in the hilly metropolitan suburbs of Japanese cities. This paper deals with the actual state of open space in the hills from a phytosociological viewpoint with special reference to that of the Tama Hills, located west of Tokyo, as a fundamental consideration for landscape conservation under the existing conditions. First, general characteristics of the actual vegetation of the hills of Japan are considered and it becomes evident that the areal ratio of secondary forest in the hills, which was used as coppice in the traditional agricultural system until the so-called "fuel revolution" in Japan, is still extremely high. Secondary forests in the Tama Hills have been rapidly decreasing since the World War II and they have been replaced by urban land use under the technological support of machinery for large-scale landform modiication. As a result of the survey on preserved secondary forests dominated by Quercus serrata in a part of the Tama Hills area, forest communities still maintain their coppice character and, at the same time, express the qualitative and spatial difference of habitats. On the other@ hand, weed communities distributed in the artificially modified residential sites where houses are not yet built show that they have been maintained for more than ten yen years with simple floristic composition and suggest that the natural potentiality of the land becomes very poor. Moreover, distribution patterns of the communities indicate a difference of land characteristics and, above all, the surroundings of cut and fill boundaries are characterized by the Cassia nomame-Miscanthus sinesis community which is normally recognized as existing on high-water beds along rivers.
多摩丘陵の緑地現況に関する植生学的考察
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