ハイマツ群落の動生態学的研究

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In the present paper the dynamics of the Pinus pumila community at Mts. Taisetsu was treated. The following items were principal subjects of the present work ; 1. Correlation of topography, wind exposure and snow depth with the variation in the cover and height of Pinus pumila communities. 2. Ecological compositons of the subalpine communities neighbouring to the Pinus pumila community and their change accompanied with the variation in the cover and height of Pinus pumila communities. 3. The analysis of growth habit of a Pinus pumila plant. 4. Regeneration of the Pinus pumila community. The results are asfollows : 1. The variation in the cover and height of pumila pumila communities is closely related to the degree of wind exposure and snow depth in high mountoins in winter together with microtopographic change. The height and coverage of Pinus pumila communities decreases gradually when the wind exposure increases in degree, but it decreases abruptly when the snow depth reacheds the critical depth of possible establishment of the Pinus pumila community. 2. Four vegetation types of community are distinguished in the subalpine communities neighbouring to Pinus pumila. community, (i) a community rich in higher plants (i.e. Empetrum, Rhododendron, Vaccinium}, (ii) a community rich in lichens (iii) alpine community, (iv) a community poor in higher plants.The occurrence of these four types is dependent of the variation in the cover and height of Pinus pumila communities. According to the decreace of the coverage of the Pinus pumila community, the types change from (i) to (iv). 3. A plant of Pinus pumila maintains constant growth rate in every growth stage. Due to its creeping habit, Pinus pumila communities hold a reasonable community height matching with the snow depth and the degree of wind exposure in high mountains in the winter season. 4. The regeneration of the Pinus pumila community is mainly due to a vegetative regeneration by adventive roots, and it was shown to be advantageous to the maintenance of the dominance of the Pinus pumila community. In the Pinus pumila belt, the seasonal wind blown from north west in winter affords considerble influence on natural environments. It affects the variation in the cover and height of Pinus pumila communities and forms the asymmetric rige on north-south mountain ranges in Japan. Many alpine plants are subject to the wind exposure and their existence was secured by the estableshment of Pinus pumila communities, while the occurrence of alpine plants and patterned grounds are disturbed by the establishments of Pinus pumila communities. In conclusion, Pinus pumila communities regulate, not only themselves but also the alpine communities mechanically and functionally under severe high altitudinal climatic conditions of Mts. Taisetsu. Finally, the asymmetrical arrangement of the Pinus pumila community and the alpine communities in the high altitudinal mountains are discussed in relation to the topographic arrangement which has been caused by the prevailing N-W directed wind in winters and heavy snow accumulation in high mountains. As a result, the authors offered a model of the arrangemental pattern of the Pinus pumila community, the subalpine and alpine communities associated the polygon soils and solifluction.
北海道大学の論文
1983-12-20

ハイマツ群落の動生態学的研究

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