Differentiation of topo-communities along topographical gradients

本研究旨在阐明植被沿地形环境梯度的分异格局及其控制因素。在盛行的宏观气候条件下，通过土壤水分状况、土壤养分、土壤深度、土壤表层物质稳定性等地形环境因子划分出的植物群落或斑块对坡度上某一立地的植物群落性质具有决定性的影响。Sieboldii、黑叶楠和栎属。在中尺度地形生境偏好中，山顶坡被常绿无顶乔木覆盖，岩脊完全由铁杉、赤松、小花松等针叶树占优势，谷底附近的下坡以落叶乔木如水龙、桑树等为主。在特定的生境上，如山区或小岛的小山峰、狭窄的脊顶、迎风坡顶等，可以观察到群落分化的有趣格局，这种格局特别是被以Eurya spp、Symplocos spp、Ilex spp等为优势的微叶群落所覆盖。当对环境胁迫更敏感的无叶树的生长或表现受到抑制时，小叶树成为优势树。因此，地形生境本身具有一个一般的竞争等级，这是具有不同适应特征的不同生态类群依次偏爱的。

The present study intended to clarify the differentiating pattern of vegetation and its controlling factors along topographical environmental gradients. The plant communities or patches which are differentiated through topographical environmental factors, such as soil moisture status, soil nutrients, soil depth, and stability of soil surface materials etc. have decisive effect on the nature of plant community on a certain site on the gradient, under the prevailing macro-climatic conditions.In the subtropical/warm-temperate zone, for example, the climax forests are dominated by evergreen notophyllous trees such as Castanopsis cuspidata var. sieboldii, Machilus thunbergii and Quercus spp. In a mesoscale topographical habitat preference, crest slope is covered by the evergreen notophyllous trees, rocky ridge is exclusively dominated by conifers such as Tsuga sieboldii, Pinus densiflora, and Pinus parviflora, and lower slope near the valley bottom is dominated by deciduous trees such as Euptelea polyandra, Morus etc. An interesting pattern of community differentiation can be observed on a specific habitats such as small peak within a mountainous area or in a small island, narrow ridge top, top of windward slope, etc., which are specifically covered by a microphyllous community dominated by Eurya spp., Symplocos spp, and Ilex spp., etc. They are competitively inferior to the notophyllous community. And the microphyllous trees become dominant when the growth or performance of the notophyllous trees, which are more sensitive against environmental stresses, are suppressed. Thus the topographical habitat itself has a general competitive hierarchy that is preferred successively by different ecological groups having various adaptational traits.