鹿回头造礁石珊瑚群落多样性的现状及动态

CURRENT SITUATION AND DYNAMICS OF SPECIES DIVERSITY IN HERMATYPIC CORAL COMMUNITY ON LUHUITOU FRINGING REEF

通过对鹿回头岸礁（１０９°２８＇Ｅ，１８°１３＇Ｎ）造礁石珊瑚群落进行系统取样调查，分析了现有群落整体的成分组成、α－多样性和β－多样性及其在环境梯度上的变化；根据现有群落实际是处于不同演替时期地段的复合体的特点，把处于相同演替时期地段的综合特征作为分析群落整体在相应时期多样性特征的依据，探讨了群落演替过程中的多样性动态。研究发现：①中等水深（２．５～５．０ｍ）地段的物种多样性平均值高于其他地段，环境条件适于大多数种类的生长。是该岸礁造礁石珊瑚分布的主要地段；②群落目前的类群组成中澄黄滨珊瑚Ｐｏｒｉｔｅｓｌｕｔｅａ为优势种；滨珊瑚属Ｐｏｒｉｔｅｓ、菊花珊瑚属Ｇｏｎｉａｓｔｒｅａ和鹿角珊瑚属、Ａｃｒｏｐｏｒａ为优势属，蜂巢珊瑚科Ｆａｖｉｉｄａｅ、滨珊瑚科Ｐｏｒｉｔｉｄａｅ和鹿角珊瑚科Ａｃｒｏｐｏｒｉｄａｅ为优势科；③鹿回头造礁石珊瑚群落的发展过程中，物种多样性表现出如下的变化格局：群落总种数在０～１０ａ之间缓慢增长，１０～４０ａ之间迅速增长，４０～６０ａ增速下降，６０ａ以后逐渐稳定；多样性指数（如Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ指数）和相应的均匀度指数在０～２０ａ均呈迅速增高趋势，在４０ａ以后呈逐渐减缓的下降趋势?

The present hermatypic coral community is in fact composite of sites at different successional age.Based on the data collected from systematic sampling on the community, the composition of species,α-, β-diversity,their variations along envirgnmental gradients and the dynamics of species diversity were analyzed.Major conclusions from this research are:1.Sites in middle depth(2.5～5.0m)have significantly higher species diversity than other areas,which indicates that area in this depth is the optimum habitat for most hermatypic corals;2.Porites lutea is the dominant species;Porttes,Gontastrea and Acropora are the dominant genus;Faviidae,Poritidae and Acroporidae are the dominant families in the existing community;.3.During the community succession,.the specied diversity of hermatypic corals exhibits the following temporal pattern:The increase rate of total number of species(TNS)is low in initial succession stage(0～10a)but high in following phases(1～40a), then it declines in subclimax stage(40～60a)until TNS approaches saturation in climax stage(>60a).Both of the increase of species diversity index(DI)and sevenness index(EI)are very sharp in earlier phases(0～20a)9then decline gradually(40～60 a), and become basically stable at last(>60a).However,these two kind indices of diversity show a distinct divergency in the middle serial stages(20～40 a).After the sharp increase in initial phases,DI keep increasing(20～40a)but at a much lower rate until it approaches its maximum in about 40 years,while EI comes to its maximum in less than 15 years,shows little fluctuations in 15～30 years and then begins to decrease in 30 years;.4.The species diversity in hermatypic corals community and its dynamics is proposed to be determined by the biological characteristics of each species,habitat heterogeneity,their spatial and temporal variations in succession process.