RESPONSES OF FOREST SYSTEMS TO CLIMATIC FLUCTUATIONS IN YAKUSHIMA ISLAND,SOUTHERN JAPAN

森林生态系统在自然和人为干扰的作用下，受到全球或局部环境的各种变化。全球变化，包括不同层次的气候波动，影响森林生态系统的功能，结构，并最终物种组成。本合作研究的目的是了解和评估森林生态系统对这些外部影响的反应，从不同层次上从叶到枝模块，个人，人口，社区和景观，这必须促进机制的理解全球变化对自然生态系统的影响。选择日本南部屋久岛作为研究地点，因为它代表了典型的天然森林，经常受到台风等自然干扰的影响。1993年13号台风是1945年以来影响日本的第三个最强台风，在屋久岛有记录以来风速最大。从而严重影响了地形 ...更多信息 和植被，特别是在岛屿的西南侧。地表侵蚀和滑坡频繁发生，主要是由于花岗岩基底遭受了较深的风化。滑坡虽然不可避免地破坏其上的森林，但森林本身及其组成树种对台风的抵抗力相对较强。森林植被对地形环境梯度如土壤水分和养分条件表现出分化格局。也许这些树对强风和当地土壤条件的适应性更强或更弱。从物质生产和分支自主性的角度研究了常绿阔叶树的枝构件，结果表明，万年青阔叶树的分支具有不同程度的自主性。在岛上的三个不同地点的叶寿命，叶大小和一些其他拍摄物候特征进行了比较。万年青叶的寿命为1 ~ 5年，叶的寿命随叶的大小而变化。不同底质上的植被演替表明了先锋树种的生境偏好和随后演替序列的分化。气候和地质条件的限制可能会对不同地点的不同物种组合进行分类，即使是在屋久岛的一个小岛上，本研究项目的进一步发展可能会加深这一认识。少

Forest ecosystem has been subjected to various changes of global or local environment due to natural as well as human induced eco-disturbances. Global changes including climatic fluctuations at various levels affect on function, structure, and eventually species composition of the forest ecosystem. The objective of the present co-operative research was to understand and evaluate responses of forest ecosystem against such external impacts at several different levels from leaf to shoot module, individual, population, community, and landscape, and this must facilitate mechanistic understanding of global change impacts on natural ecosystem. Yakushima Island of southern Japan was selected as study site as it represent typical, natural forest which is regulary influenced by natural disturbances such as typhoon. Typhoon No.13 of 1993, the thirs most powerful typhoon affected Japan since 1945, had strongest wind velocity ever recorded in Yakushima Island. Thus it seriously affected topography … More and vegetation especially on windward south-western side of the island. Surface erosion and land slides frequently occurred due mainly to granitic substratum which was suffered deep weathering. Although landsliding inevitably destroy the forest on it, the forest itself and its component species were relatively resistant against typhoon. Forest vegetation exhibited differentiating pattern against topographical environmental gradients such as soil water and nutrient conditions. Probably the trees are more of less adaptive against strong wind and local soil conditions. Shoot module of such trees were also studied from the viewpoint of matter production and branch autonomy, the results showed that the branch exhibited various levels of autonomy in evergreen broad-leaved tree. Leaf life span, leaf size and some other shoot phenological characteristics were compared at the three different sites of the island. Life span of evergreen leaves were 1 to 5 years and leaf life span changed in parallel with leaf size. Vegetation succession on different substratum indicated habitat preference of pioneer trees and the subsequent differentiation of successional seres. Climatic and geological constraints may act to sort different species assemblages at different sites even within a small island of Yakushima, and further development of this study project may deepen this insight. Less