Invertebrate richness and diversity in parks situated along a gradient of urbanisation

Urbanisation entails significant habitat loss leading to degradation of biodiversity and ecosystem services, and fragmented landscapes. Urban parks, which can take the form of large forest remnants, lawns, or a combination of the two, provide habitat for some species. The type of park and its location relative to other land uses affect the communities of species it supports. This study examined the composition of invertebrate communities, with emphasis on species richness and diversity of Coleoptera in parks along a gradient from low to high levels of urbanisation intensity, measured as the proportion of impervious surface within a surrounding buffer. The diversity of invertebrates differed only between parks at each end of the urbanisation gradient and a consistent, although non-significant, trend of increasing diversity from high to low intensity surrounding urbanisation. Parks situated closest to a large green space (> 30 ha in area; typically semi-natural, such as a reserve), had highest invertebrate richness, abundance and diversity. Increasing proportion of impervious surface had only a minor impact on invertebrate communities, likely due to the pre-selection of species tolerant to fragmentation and non-native vegetation. However, increasing urban densification will likely harm invertebrate diversity. Coleoptera communities were similar across all parks, although parks with patches of high-quality vegetation presented slightly different assemblages, potentially supporting less urban-tolerant species. While lawns are not completely sterile environments for invertebrates, enhancing vegetation heterogeneity in urban green spaces and creating green corridors for dispersal will improve invertebrate richness and diversity in urban parks, while retaining their amenity value.