Latitudinal variation in the diversity-disturbance relationship demonstrates the context-dependency of disturbance impacts
Bracewell, Sally (2021), Latitudinal variation in the diversity-disturbance relationship demonstrates the context-dependency of disturbance impacts, Dryad, Dataset, https://doi.org/10.5061/dryad.w9ghx3fnw
Aim: The shape of the diversity-disturbance relationship is context-dependent, but the mechanisms driving this context-dependency are unclear due to limited standardised empirical assessments across different environmental and ecological settings. At seven sites and over 20o of latitude, spanning both temperate and tropical systems, we measured community response to a fine-scale experimental disturbance gradient in communities of benthic invertebrates.
Location: East coast of Australia (16.48oS – 36.43oS)
Time period: 66 weeks (August 2012 – November 2013)
Major taxa studied: Benthic marine invertebrates
Methods: Communities 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 (0-100% community clearance) on alpha and beta-diversity measures were assessed.
Results: In the tropics, richness and diversity increased with disturbance as the creation of free space allowed for the colonisation 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, changes in species abundances were primarily responsible for compositional changes, reflecting the shift to algal dominance under conditions of high disturbance.
Main conclusions: The 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 explain this pattern.