The species-area relationship derived from species-specific incidence functions

The species - area relationship (SAR), describing the increase in species number ( S) with increasing area ( A), is one of the most robust patterns in ecology with great significance for conservation. The SAR is generally formulated as a power function, S = kA(z), although the semilogarithmic form S = a + b log A has often been used by botanists. Here we unite the two forms by deriving SARs from the incidence functions of the species that make up the community. We show how the decisive scaling parameters z and b relate to the properties of individual species, and highlight why the biological interpretation of SARs has been so enigmatic.