基础与实现生态位及其中心点的涵义与测度

本对ｎ维超体积生态位定义作了进一步的阐明。物种的“基础生态位”为其分布区的环境参数及其生理学容忍性和要求所决定，而“实现生态位”则为该物种种群在某一特定群落中所处的环境参数所确定。一物种的生态位中心点为该物种生态位空间中具最佳适应的位置。进而根据是否在测度中考虑进物种分布参数，则分别称为理论与实现生态位中心点。以广东鼎湖山厚壳桂群落在利用土壤营养方面为例，说明物种生态位中点等指数的测度。

On the Implications of Fundamental,Realized Niche and Niche Center

The implications of fundamental and realized niche proposed by Hutchi-nson in 1957 are discussed.Species realized niche will never overlap based on hisdefinition,contracting with that in the realistic environmental array.To remedvthe confusion in using the concepts of fundamental and realized niche,we sug-gest that these two notions should be defined for a species or a species population individually.A species fundamental niche will not be cenfined in a particularcommunity but in its areal or even in some hypothesized environmental characte-ristic combination which allows the species to survive and reproduce,i.e.,funda-mental niche is determined by the species physiological tolerance or requirements.It should be an entity or hypervolume in the n-dimensional niche space.A speciesrealized niche is described as the environmental characteristic combinations thatsurround a species population in a particular community.In the niche space,it ismanifold.Another new concept,niche center,is defined as the point or a compart-ment where the species response is optimal within the niche space.When a speciesdistribution is ignored or the species has a homogenous distribution within the a-vailable compartments of the compartmentalized niche space,the point defined iscalled its theoretical niche center.Usually species disstribution is uneven andthe point defined is called its realized niche center.The distance froma species rea-lized center to theoretical niche center is defined as its niche deviation.And thedegree of a speices niche hypervolume diffuse within the niche space is describedwith the niche diffusion index.Formulae are proposed for such metrics and anexample from a south China subtropical evergreen forest community is presented.