The effects of landscape heterogeneity and change on beetle community composition

Biodiversity conservation in anthropogenically modified landscapes requires consideration of the interactions between communities of species, the spatial heterogeneity of landscapes and their change through time. The significance of insects for understanding the biodiversity crisis is well known. However, we lack even basic information about the vast majority of insects and the response of many taxa to landscape heterogeneity is poorly understood. Several groups of beetles, especially ground beetles (Carabidae), are frequently employed as indicators in landscape-scale studies. To more fully understand the range of responses to landscape heterogeneity and change in beetles, this thesis considers three beetle communities in varied landscape contexts. A novel application of historical land use data was used to consider time lag in woodland ground beetles’ response to landscape change. Flower-visiting beetles and coprophilous beetles were considered in the context of an agriculture-dominated landscape mosaic and on a gradient of urban land use, respectively. All three communities were modified to some degree by landscape heterogeneity, with responses mediated by traits such as body size, dispersal ability and feeding guild. Woodland ground beetle communities were more strongly linked to landscape patterns in the 18th and 19th centuries, providing evidence for an extinction debt that may be on the order of 200 years. Flowervisiting beetle communities were shaped by mesoscale landscape composition, especially the amount of tree cover and gardens in the surrounding 200 metres. A widespread but little-studied genus of flower-visiting beetles (Scraptiidae: Anaspis) displayed heterogeneous sex ratios among the sites visited; the distribution and sex ratios of two species were linked to local habitat composition and structure, measured using LiDAR data. Coprophilous beetles were less speciesrich in urban sites, but some species appeared to benefit from urbanisation. Potential applications of these results are considered along with suggestions for future research in landscape entomology