Spatial patterns of canopy tree distribution were analyzed through the Box Counting Method in fractal geometry. A map showing the position of 4102 individual canopy trees, belonging to 55 species, was compiled from an inventory of a fourteen hectare research plot, established in an evergreen oak forest, in Kasugayama Forest Reserve, Nara City, western Japan, in 1991. A newly proposed fractal model allows the saturation of the number of boxes in smaller box sizes, and was successfully used for the calculation of fractal dimensions of sixteen common species, with a sufficient sample size for computation. The calculated dimensions were in a range between 1.19 of Ckamaecyparis obtusa Sieb. et Zucc. and 1.73 of Quercus salicina Blume, and their variations among species were compared with the dimensions of valley (1.47) and ridge (1.43) lines. Larger fractal dimensions tended to be confined to a species with a wider distribution and with habitat less dependent on topography. Smaller fractal dimensions were observed from species with patchy distribution. Species with intermediate fractal dimensions had a distribution pattern fairly dependent on a valley or ridge site. In conclusion, fractal geometry is applicable to the spatial patterns of forest trees and results in fractal dimensions which appear to indicate a degree of topographic dependency in species' distribution.

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The distribution and growth environment of Pteridophyllum racemosum Sieb. et Zucc. (Pr, hereafter), a herbaceous plant of Papaveraceae endemic to Honshu, were studied through field surveys and a literature review. Based on growth environment, the Pr population was divided into two types. The first, named D-type here, comprises the populations shaded by deciduous trees and shrubs, which are mainly situated on the steep lower slopes of small valleys. The second, named C-type, comprises the populations shaded by conifer trees, such as Abies veitchii and A. mariesii, on flat ground or gentle slopes. The horizontal and vertical distributions of these two Pr types are distinct. D-type is distributed mainly in northern Honshu (Aomori, Akita, Yamagata, Miyagi, Fukushima and Niigata) and tends to be on the Sea of Japan side. In contrast, C-type is distributed mainly in central Honshu (Iwate, Fukushima, Tochigi, Tokyo, Saitama, Yamanashi, Nagano, Niigata, Shizuoka and Gifu), and tends to occur inland and in regions on the Pacific side. Vertically, D-type is distributed on a lower elevation (280m-1400m) than C-type (1040m-2565m). Local population size of D-type is generally smaller than that of C-type. The distinction between D- and C-type did not correlated with the snow depth of the areas. Instead, the distributional pattern of C-type or D-type corresponds respectively to the presence or absence of dense coniferous forest, to the survival or extinction of coniferous forest within the area during the Post Glacial Period, and to the presence or absence of some relict conifers, such as Pinus koraiensis, Picea maximowiczii (in central Honshu) and P. glehnii (in northern Honshu), that reportedly covered a wider area in the Last Glacial Period. These facts suggest that the distributional pattern of the two types of Pr might be caused by differences in climatic and vegetational changes between the associated areas during the Post Glacial Period. Thus, on the Sea of Japan side, Pr once growing in coniferous forest (C-type) in the Glacial Period, became mostly extinct due to the collapse of coniferous forests under the heavy snow conditions of the Post Glacial Period, with a few remaining as D-type. In contrast, in inland regions and on the Pacific side, the coniferous forest has continued to survive, so Pr of C-type has also thrived here throughout the Post Glacial Period.

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A phytosociological survey was carried out on Quercus mongolica var. grosseserrata forest in Nishitsugaru district, Aomori Prefecture. Two associations were recognized, based on floristic composition. The distributions of the two associations are closely related to the precipitation level, total snowfall and topography. The first association, Tripetaleio-Quercetum mongolicae, is distributed in mountainous areas where upheaval, denudation and dismantling of the ground frequently occurs. This association is found only in areas of higher precipitation and total snowfall. The second association, Lindero membranaceae-Quercetum mongolicae grosseserratae, is found widely and tends to be distributed mainly on marine terrace to the west or north of the area investigated. The floristic composition of these associations was compared with that of Quercus mongolica var. grosseserrata forests investigated by other researchers.

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We examined the effects of ammonium sulfate on the vegetation of two ski runs subjected to differing levels of landscaping during their creation. Stands treated with ammonium sulfate had greater biomass than untreated stands on both the ski runs. Ammonium sulfate treatment did not affect the species richness of stands on the 'Utopia' Course, which had received extensive slope modification. However, species richness was lower in stands treated with ammonium sulfate than in untreated stands on the 'Challenge' Course, which had been modified relatively little. The lower species richness on the Challenge Course was due to the lower frequency of short herbs, such as Ixeris dentata, Lysimachia japonica and Equisetum arvense, and tree seedlings, e. g. , Cryptomeria japonica and Acer micranthum. These species were believed to have been excluded by the predominance of large perennial herbs, Artemisia montana. Based on these results, we concluded that spraying ammonium sulfate on the snow surface in winter greatly influenced vegetation structure, and the effects differed with the extent of landscape modification during formation of the ski slope.

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The vegetation of breeding sites of streaked shearwaters was studied to determine the effect of the birds' burrow-nesting on the vegetation of Biro Island in Kochi Prefecture, southwestern Japan. The vegetation changes along an altitudinal gradient on Biro Island, in the order of : wind-exposed grassland (e.g. Carex oahuensis var. robusta-Miscanthus condensatus community), wind-exposed evergreen scrub (e.g. Camellia japonica community, Eurya emarginata community and Ardisia sieboldii community) and evergreen broad-leaved forest (Arisaemato ringentis-Perseetum thunbergii). Burrow-nests were often found under the roots of C. oahuensis var. robusta and M. condensatus on the grassland and near the stems and roots of trees in the forest. There were no significant differences in burrow density among the three areas of vegetation. Compared with insular vegetation dominated by C. oahuensis var. robusta or M. condensatus, mean species per stand tended to be low on Biro Island. The conspicuous growth of C. oahuensis var. robusta and M. condensatus appeared to lead to poverty of plant species on the grassland. This study also suggests that the evergreen broad-leaved forest has provided the streaked shearwater on Biro Island with a stable habitat at present, although the burrow-nesting is causing some modifications in the species composition.

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Dynamics of vegetation structure and composition in a natural scrub community were investigated for six years after a fire on Mt. Tenjo, Kozu-shima Island, Izu Islands. Vegetation coverage of the burnt area was still low six years after the fire. Many burnt trees were resprouted, but there were very few seedlings. To assess the effects of soil surface disturbance on vegetation regrowth, pins of two different sizes were set up below regenerating shoots, Miscanthus condensatus tussocks, and rocks (protected sites) or with no protection (open sites) and re-counted the following year. Many small pins at open sites were damaged or lost by soil surface disturbance, but few were damaged or lost at protected sites. More small pins were damaged or lost than large pins. By implication, more small seedlings would be affected by soil surface disturbance at open sites than at protected sites. Species with a small initial size would be more likely to die by soil surface disturbance than species with a greater ability to sprout or with a larger initial size. The vegetation of this area will probably recover slowly by invasion of seedlings in protected sites.

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