Vegetation—a Mosaic of Discrete Communities, or a Continuum

A simulation model, using the often observed log-linear relationship between the relative abundance and rank of species, shows that vegetation will tend to form a series of communities of constant composition along an environmental gradient even if the constituent species are initially responding independently to those environmental changes. The discreteness of these communities increases with increasing conformity to the log-linear relationship. An index quantifying this conformity (range 0-1.0) is defined and a method for estimating it from field vegetation data devised. In three vegetation data sets tested the conformity index was 0.0, 0.32 and 0.37.