Oil Mallee Plantings Increase Diversity of Beetles (Coleoptera) and Other Terrestrial Invertebrates within a Cropping Field

Planting oil mallee (Eucalyptus spp.) belts in cropping fields introduces a new native, perennial-based habitat type to the previously homogenous, exotic, annual-based cropping environment. The purpose of this investigation was to determine if oil mallee plantings enhance the diversity and abundance of ground-dwelling invertebrates, especially beetles, in an agro-forestry landscape by comparing four habitat types (wheat field, oil mallee belts, remnant woodland, and remnant roadside vegetation). Belts of oil mallees within a cropping paddock had substantially different assemblages of ground dwelling arthropod orders to the surrounding wheat crop. Of 93 coleopteran species trapped, 27 were found throughout all four habitats in the landscape, with the remaining species creating a strong distinction between the assemblages in the cropped areas and other habitat types in terms of species competition, diversity and abundance. Coleopteran assemblages in oil mallees were more similar to those in woodland and roadside remnants than to those in the adjacent wheat crop. Arthropod assemblages, in particular coleopterans, within this agricultural environment were thus influenced by habitat type. Oil mallee farming systems appear beneficial for arthropod conservation in the wheat belt of Western Australia.