Ground arthropod community structure in a heterogeneous urban environment

Despite being conspicuous and influential features of the biosphere, urban ecosystems have been neglected in ecological research. Arthropods are abund ant in urban settings, but little is known about how these animals respond to urbanization. We systematically monitored the structure of ground arthro pod communities for 12 months at 16 sites representing the four most abunda nt forms of urban land use (residential, industrial, agricultural, and dese rt remnant) in a rapidly growing metropolitan area (Phoenix, AZ). Although taxonomic richness was comparable among land-use types, community compositi on differed, with certain taxa being uniquely associated with each form of land use. Three taxa (springtails, ants, and mites) were extremely widespre ad and abundant, accounting for over 92% of captures; when these three taxa were excluded from analysis, however, differences were revealed in arthrop od community composition with urban land use. Trophic dynamics also varied with land use: predators, herbivores, and detritivores were most abundant i n agricultural sites, while omnivores were equally abundant in all forms of land use. These community-level differences resulted from taxon-specific r esponses to habitat structure, which varied with land use. Because arthropo d community structure is affected by habitat structure and land use, and be cause arthropods play key roles in nutrient cycling, organic matter decompo sition, pollination, and soil aeration, the spatial heterogeneity of urban ecosystems therefore may affect ecosystem functioning. (C) 2001 Elsevier Sc ience B.V. All rights reserved.