Neighborhood Models of Plant Population Dynamics. 4. Single-Species and Multispecies Models of Annuals with Dormant Seeds

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Abstract
Neighborhood population-dynamic models are developed for single-species and multispecies communities of annual plants with seeds that may lie dormant through one or more growing seasons. Dormancy-induced changes in lifetime to predict the abundance of species in the whole community. The species abundance in 94% of the samples may be explained by one of the predictions of the dynamics model. For most samples, the model predicts a concave dominance-diversity curve with a large number of rare species, but indicates that there may be a smaller proportion of rare species in communities where population growth is less restricted by competition or mortality. It is concluded that the theories associated with the log-series and lognormal models, which have been criticized previously for a lack of ecological realism, provide unsatisfactory explanations for species abundance because they are conceptually unsound and the models on which they are based rarely provide a satisfactory description of samples. This conclusion undermines the use of the diversity index .alpha. associated with these models. The dynamics model predicts the species-abundance pattern of most samples with greater accuracy and provides an explanation of species abundance based on recognized and testable ecological principles.