Convergence in Vegetation Structure along Analogous Climatic Gradients in California and Chile

A series of plant communities along analogous climatic gradients in southern California and central Chile has been analyzed to determine the extent of convergence in a variety of ecologically significant characters. Results show that, despite distinct genetic histories, the structure of the vegetations of these areas has converged under similar climatic constraints. Such characters as species richness, growth form, leaf duration, leaf size, and spines are quantitatively more similar between floristically distinct yet climatically analogous sites on the two continents than between floristically similar but climatically distinct sites a short distance apart on the same continent. Such findings, which hold true for both the native woody vegetation and the partially exotic herbaceous understory, provide quantitative support for the general hypothesis that plant form and community structure are higherly determined, regardless of genetic constrains, by environmental parameters.