Spatial aggregation and the species-area relationship across scales

TL;DR

This paper introduces a spatially explicit model linking species abundance, beta diversity, and species-area relationships, explaining the tri-phasic behavior across scales using geometric and neutral theory assumptions.

Contribution

The paper presents a novel Poisson cluster process model that exactly connects RSA, beta diversity, and SAR, providing analytical expressions for these ecological measures across scales.

Findings

Reproduces tri-phasic SAR behavior from local to continental scales

Provides analytical expressions for endemic area relationship (EAR)

Explains spatial aggregation effects on species distribution

Abstract

There has been a considerable effort to understand and quantify the spatial distribution of species across different ecosystems. Relative species abundance (RSA), beta diversity and species area relationship (SAR) are among the most used macroecological measures to characterize plants communities in forests. In this article we introduce a simple phenomenological model based on Poisson cluster processes which allows us to exactly link RSA and beta diversity to SAR. The framework is spatially explicit and accounts for the spatial aggregation of conspecific individuals. Under the simplifying assumption of neutral theory, we derive an analytical expression for the SAR which reproduces tri-phasic behavior as sample area increases from local to continental scales, explaining how the tri-phasic behavior can be understood in terms of simple geometric arguments. We also find an expression for the endemic area relationship (EAR) and for the scaling of the RSA.