Soil type, vegetation cover and temperature determinants of the diversity and structure of dung beetle assemblages in a South African open woodland and closed canopy mosaic

Abstract

Regional biogeographical patterns result from a complex combination across habitat, climate and environmental variables. Biotic and abiotic variables strongly influence the diversity and spatial distribution patterns. However, very few studies analyse the close interaction and effect of environmental variables on diversity at fine spatiotemporal scales. In this study, we evaluated the influence of soil type, vegetation cover and temperature on species diversity and functional structure of dung beetle assemblages. Dung beetle species were sampled using pitfall traps baited with cattle dung from sandy and clay soils in open woodland and closed canopy areas in Mkhuze Game Reserve, KwaZulu-Natal, South Africa. We performed a PERMANOVA, a PERMDISP and an NMDS to analyse differences in species composition between soil and vegetation cover types. To test the effect of environmental variables on species richness and abundance, we performed a generalised least squares model. Lastly, we searched for nodes using a bipartite analysis to evaluate network’s potential modularity. We collected 1439 specimens comprising 27 species and 13 genera. Species composition differed between environmental variables. Soil type was the most important driver for changes in dung beetle species composition. Species richness and abundance were influenced by the interaction between soil type and vegetation cover. The combination of microenvironmental preferences potentially influenced the dung beetle assemblage diversity and functional structure. Combining all these preferences may act as a dilution mechanism of interspecific competition in saturated habitat conditions, reducing the number of species that potentially interact and generating a modular network structure of the assemblage.