Differentiation of topo-communities along topographical gradients

点击翻译按钮获取中文摘要

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.