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

本研究旨在揭示富士山林木线周边植被动态及其环境因子。对富士山西北坡坡面植物群落结构与坡面过程的关系进行了研究。在海拔2700米至2950米之间的斜坡上发育了阶梯式微地形，在海拔2800米至2850米之间有一个特别明确的结构。这种阶梯式微地形几乎肯定是冰缘地形，是植物群落岛屿发展的基础。这些群落集中在台阶的悬崖部分，在平坦的阶地部分几乎没有观察到任何增长。地温监测和漆线暴露实验表明，砾石在梯田上是不稳定的，在悬崖上是稳定的，认为地表物质的稳定性决定了植被的分布。群落组成多样，上坡以黄柳为主，地衣为主。低坡以落叶松和白桦等乔木树种为主。此外，山参天的年轮从上到下逐渐减少，说明建立时间不同。根据这些发现，可以预测，以阶梯微地形为基础，富士山西北坡的林木线将发生向更高海拔的初级演替。此外，树高与树龄的关系分析显示，低海拔地区越老越长伸长，而高海拔地区越老越长加厚而不是伸长。这一事实表明，落叶松灌丛群落的形成是由暴露于恶劣环境的时间长短控制的。

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.