Research on the tree-line dynamics and environmental change on Mount Fuji

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The purpose of this study is to reveal the vegetation dynamics and its environmental agents around the tree-line on Mt. Fuji. An investigation was conducted into the relationship between slope processes and plant community structure on the north-western slope of Mt. Fuji. A stepped microtopography has developed on this slope between 2700 m and 2950 m elevation, with a particularly well-defined structure identified between 2800 m and 2850 m. This stepped microtopography is almost certainly periglacial, and has been a foundation for the development of islands of plant communities. These communities are concentrated on the cliff sections of the steps, with virtually no growth observed on the flat, terrace sections. On the evidence of ground temperature monitoring and paint-line exposure experiments, gravel is unstable on the terraces and stable on the cliffs, and it is considered that distribution of vegetation has been determined by stability of the surface material. Composition of communities is diverse : on the upper slopes, Salix reiini is predominant and lichens are prominent. The lower slopes are dominated by arboreal species including Larix kaempferi and Betula ermanii. In addition, the annual rings of L kaempferi become few from lower to upper slopes, suggesting establishment at different periods. From these findings, it is predicted that primary succession of the tree line to a higher elevation will occur on the north-western slope of Mt. Fuji, using the stepped microtopography as a foundation. Furthermore, the analysis of the relationship between tree-height and tree-age has shown a tendency, in the lower altitude part the older the greater elongation growth, in the higher part the older the greater thickening growth not elongation one. This fact suggests that a larch scrub community is formed controlling by the length of exposure to the severe environment.