南亚热带森林3层次物种多度之广义泊松分布模型

生物群落中物种多度分布(species abundance distribution)呈典型的倒J形,即其中存在许多稀有种、少量常见种.物种多度分布模型研究有助于解决森林生态恢复中的物种配置等实际问题.本研究考察了一种过分散(over-dispersion,或称超分布,即方差大于均值)的离散型分布,即具有λ和α两个参数...

Using Generalized Poisson Distribution to Model the Patterns of Species Abundances in Three Layers of South Subtropical Forest

The species abundance distribution(SAD) in a biological community showed typical inverse J-shaped pattern, and the SAD modelling study was contributed to solve practical problems such as the species configuration in forest ecological restoration. This study examines whether a discrete distribution with over-dispersion(i.e., variance>mean), the generalized Poisson(GP) distribution with two parameters, λ and α, can describe the SAD pattern, and whether its parameters are related to community species diversity by using the data from the three layers of a lower subtropical mixture forest in Dinghushan Biosphere Reserve, South China. The results showed that the observed SADs for all three layers of the forest showed similar inverse J-shaped distribution curves and followed the zero-truncated GP, with significantly decreasing λ and slightly increasing α from the tree, shrub to herb layer in the community. The parameter α better reflected the species diversity than λ, and thus the former could serve as a measure of the species diversity in a community. Comparisons between the GP and the Poisson lognormal(PLN) distribution showed that the former better fitted the SAD datasets than the latter for three layers. Therefore, the GP better estimated the potential species richness in the community. The GP distribution was more suitable to model the observed SAD with over-dispersed count data than the PLN, and thus the former might have a wider application prospect than the latter, especially in the estimation of the potential species richness in a community as well as on a local or regional scale and the determination of the species proportion for ecological restoration of degraded forests.