Biodiversity on urban roundabouts - Hemiptera, management and the species-area relationship

The biodiversity of insects within urban areas has been relatively little studied. Given the large and ever increasing extent of urban areas, and that the insect species richness there can be high, it is important to know the factors determining that aspect of biodiversity. In this study two of these factors, namely habitat management and area, were considered. Arboreal and grassland Hemiptera, and grassland plants, were sampled on 18 roundabouts and other road enclosed sites in the town of Bracknell. Hemiptera were sampled using suction sampling and tree beating. A significant species-area relationship was found for arboreal Hemiptera, which was strongly related to habitat diversity. For both grassland plants and Hemiptera, grassland management, by mowing, had a significant effect on species richness. Despite the management grassland plants showed a significant species-area relationship. However the effect of management on Hemiptera was great enough to outweigh any area effect. As the size of open spaces is often constrained in urban areas, altering habitat management has a greater potential. for enhancing biodiversity. For arboreal Hemiptera choice of trees for planting is of particular importance, white for grassland Hemiptera diversity would be increased with a reduction in the intensity of management, such a reduction in the frequency of mowing. (C) 2004 Elsevier GmbH. All rights reserved.