Latitudinal variation in the diversity–disturbance relationship demonstrates the context dependence of disturbance impacts

Abstract

AbstractAimThe shape of the diversity–disturbance relationship is context dependent, but the mechanisms driving this context dependence are unclear due to limited standardized empirical assessments across different environmental and ecological settings. At seven sites and over 20° of latitude, spanning both temperate and tropical systems, we measured community response to a fine‐scale experimental disturbance gradient in communities of benthic invertebrates.LocationEast coast of Australia (16.48–36.43° S).Time periodSixty‐six weeks (August 2012–November 2013).Major taxa studiedBenthic marine invertebrates.MethodsCommunities were grown on acrylic tiles and subjected to four experimental disturbance events over a 66‐week period. At the end of this period, the effect of increasing disturbance extent (from 0% to 100% community clearance) on measures of alpha and beta diversity were assessed.ResultsIn the tropics, richness and diversity increased with disturbance because the creation of free space allowed for the colonization of new recruits. In temperate communities, increasing disturbance led to a monotonic loss in species richness and a more hump‐shaped relationship in evenness and diversity. In the tropics, compositional change with increasing disturbance was driven by changes in species identities and abundances as the cover of rare species increased. In temperate regions, however, differences in species abundances were primarily responsible for compositional changes, reflecting the shift to algal dominance in conditions of high disturbance.Main conclusionsThe shape of the diversity–disturbance relationship changed over latitude, indicating that the concept of “intermediate” disturbance differs amongst these communities. Faster rates of increases in bare space, loss of species richness and a shift to algal dominance suggest that, in these systems, higher‐latitude communities are more susceptible to negative outcomes of high levels of disturbance than lower‐latitude communities. We discuss how differences in community dynamics, including competition, regional diversity and availability of propagules, help to explain this pattern.