Various responses of ground beetles in natural versus anthropogenic edges

Abstract

Worldwide fragmentation and loss of natural habitats increase the occurrence of habitat edges that are transitional zones between adjoining ecosystems or habitats. Once created, edges are distinguishable by their maintaining processes: natural vs. continued anthropogenic interventions (forestry, agriculture, urbanization). According to our history-based edge effect hypothesis (Magura et al. 2017), dissimilar edge histories are reflected in the diversity and assemblage composition of their inhabitants. Testing this hypothesis, we evaluated available information on ground beetles (Coleoptera: Carabidae) in forest edges. A meta-analysis based on 39 publications showed that the diversity-enhancing properties of edges significantly varied according to their history. Forest edges maintained by natural processes had significantly higher species richness than their interiors, while edges under continued anthropogenic influence did not. The filter function of edges was also essentially different, depending on their history. For forest specialist species, edges maintained by natural processes were penetrable, allowing these species to move through the edges, while edges still under anthropogenic interventions were impenetrable, preventing their between-fragment dispersal. For species inhabiting the surrounding habitats (open-habitat and generalist species), edges created by forestry activities were penetrable, and such species also invaded the forest interior. However, natural forest edges constituted a barrier and prevented the invasion of matrix species into the forest interior. Preserving and protecting all edges maintained by natural processes, and preventing anthropogenic changes to their structure, composition and characteristics are key factors to sustain biodiversity in forests. Anthropogenic edges may contribute to the loss of biodiversity; thus, the restoration of edges under continued anthropogenic intervention is an urgent task in conservation management. Promoting habitat heterogeneity, and reducing the contrast between these edges and the surrounding habitats (softening the edges) to encourage movement of forest specialist species through the edges are crucial tasks during restoration.

Reference Magura T, Lövei GL, Tóthmérész B (2017): Edge responses are different in edges under natural versus anthropogenic influence: a meta-analysis using ground beetles. Ecology and Evolution 7: 1009-1017.