Navigating the multiple meanings of β diversity: a roadmap for the practicing ecologist

TLDR

β‑diversity research has expanded rapidly, producing a confusing array of concepts, measures, and methods that differ in their emphasis on presence/absence versus relative abundance and on the inclusion of joint absences. The authors present a roadmap of the most widely used, ecologically relevant β‑diversity approaches, urging careful alignment of research questions with appropriate analyses and the use of null models to uncover underlying processes. They distinguish two main types of β‑diversity—directional turnover along gradients and non‑directional variation—and organize the roadmap around mission statements for each. Applying multiple measures together reveals the true nature of β‑diversity patterns, as illustrated by a case study of Indonesian coral assemblages that demonstrates the value of a multi‑faceted approach.

Abstract

Ecology Letters (2011) 14: 19–28 A recent increase in studies of β diversity has yielded a confusing array of concepts, measures and methods. Here, we provide a roadmap of the most widely used and ecologically relevant approaches for analysis through a series of mission statements. We distinguish two types of β diversity: directional turnover along a gradient vs. non-directional variation. Different measures emphasize different properties of ecological data. Such properties include the degree of emphasis on presence/absence vs. relative abundance information and the inclusion vs. exclusion of joint absences. Judicious use of multiple measures in concert can uncover the underlying nature of patterns in β diversity for a given dataset. A case study of Indonesian coral assemblages shows the utility of a multi-faceted approach. We advocate careful consideration of relevant questions, matched by appropriate analyses. The rigorous application of null models will also help to reveal potential processes driving observed patterns in β diversity.