群落物种多度的分形模型和一般性分布规律的验证与探讨

Verification and Discussion on Fractal Model and the General Pattern on Species Abundance in Community

解析群落物种间的个体数量关系,也称群落物种多度分布,被认为是理解群落物种多样性决定机制的关键。近年来已建立了许多物种多度分布模型,但却因模型众多且又难以区分而引发了许多争议。已有研究表明,对物种多度分布模型的筛选不仅要考察其与群落样本实测数据的拟合效果,还要检验其能否在更深层次上揭示某些宏观生态学现象。Su建立的分形模型拟合效果较好,并揭示了物种多度分布的一般性规律,即Nr/N1往往趋近于1∶1/2∶1/3……(Nr和N1分别为降序排序中第r位和第1位物种的个体数量)。但该模型尚未得到充分的重视,相关的验证研究也较为欠缺。鉴于此,通过一个全球性群落物种数据库资料,对该模型及物种多度分布的一般性规律进行更为详细的检验。结果显示,分形模型的实际拟合效果很好;物种多度分布的一般性规律可以得到该数据库的支持与验证。上述结果可为比较全面地理解物种多度分布、探究物种多样性的决定机制提供更加可靠的科学依据。

The analysis of individual quantitative relationship among community species,also known as the Species Abundance Distribution(SAD),is considered to be the key to understanding what determines species diversity. In recent years,numerous SAD models have been proposed on various theoretical grounds,but it is difficult to draw general conclusions about which models provide the best fit to SADs. Previous studies have shown that the screening of SAD model should not only examine the goodness of fit of SAD model with the empirical data of community samples,but also evaluate model’s ability to simultaneously explain some macro ecological patterns. The fractal model proposed by Su has good fit to the empirical data of community samples and reveals the general pattern of SAD;that is,Nr/N1 tends to be 1∶1/2∶1/3…(Nr/N1,Nrand N1 represent the number of individuals of the r-th and the first species in descending order). However,the model has not been given enough attention,and the relevant verification research is also lacking. This paper uses a global community species database to test the model and the general pattern of SAD. The results show that:(1) the fractal model has a good fit to the database;(2) the general pattern of SAD can be supported by the database. These results might provide a more reliable scientific basis for understanding SAD and exploring the determinant mechanism of species diversity.