The effect of fire on ant assemblages does not depend on habitat openness but does select for large, gracile predators
Date
2021-06-09ISSN
2150-8925Source
EcosphereVolume
12Issue
6Pages
1-16Google Scholar check
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Ecosystems can respond in a variety of ways to the same agent of disturbance. In some con-texts,fire causes large and long-lasting changes to ecological communities. In others,fire has a limited orshort-lived impact on assemblages of animals and plants. Understanding why this occurs is critical if weare to manage these kinds of disturbances across the globe. A recent synthesis proposed that these seem-ingly idiosyncratic responses tofire can be understood in the context of habitat openness pre-disturbance.Assemblages in open habitats should respond less to a singlefire event that those in closed habitats. Weprovide a test of this hypothesis by examining the response of ant (Hymenoptera: Formicidae) communi-ties to large-scalefire events in three habitats of different natural canopy openness on the Peloponnesepeninsula in Greece. We also test the hypothesis that assemblage responses tofire are trait dependent. Firesimplifies the physical structure of the environment, increases insolation, and limits opportunities for antsto exploit herbivorous feeding strategies. Consequently, we predict that ants will face a strong environmen-talfilter between unburnt and recently burnt plots, which will be reflected in their functional morphology.Our analysis shows that burnt plots have more individual ants, more species and an almost complete com-positional change relative to unburnt plots. These changes do not depend on initial canopy openness.Rather, we suggest that openness must be interpreted relative to the study taxon; for ants, openness shouldbe measured closer to the ground level. In our study, ground-level openness does not vary across the plots,which may explain the results. Furthermore, ants in burnt plots are significantly larger, have relativelylonger legs, relatively longer mandibles, and more elongate heads. This morphotypefits with our predic-tion of ants that can move and feed successfully in the burnt micro-landscape. Ultimately, more work isneeded to fully explore the relationship between habitat openness and the response tofire. Our resultsshowing afiltered set of ant morphologies in burnt environments suggest that ant traits may offer a furtherway forward to understand the faunal response tofire and disturbance in general.