Institute of Ecosystem Studies

2008 BES Annual Meeting Presentation and Poster Abstracts

Patterns in Urban Soil Biodiversity: Biotic Homogenization and Urban Vicariance
Szlavecz, Katalin
Co-Authors: E. Hornung, C. Csuzdi, Z. Korsos, F. Vilisics, P. Solymos, R. Pouyat
Abstract: Soils in cities are transported and heavily managed leading to altered soil community composition. Moreover, urban areas have been hotspots for exotic species introductions. To examine if general patterns exist in urban soil biodiversity we have compiled presence-absence data for three soil invertebrate groups, isopods, millipedes and earthworms from several cities in Europe and North America. We found that 1/ biodiversity loss or as well as presence of non-native species is taxon dependent; 2/ species rich taxa respond to urbanization more strongly; and 3/ there is a considerable overlap in species composition among cities, a process known as biotic homogenization. The proportion of homogenizing species increased in the isopod-diplopod-earthworm direction. Out of the 25 earthworm species in six cities, ten (40%) were identified as homogenizing with number of occurrences more than or equal to five. Out of the 46 isopod species found in 11 cities, seven (15.2%) were identified as homogenizing with number of occurrences more than or equal to nine. For millipedes, 36 not localized species were found in six cities and 15 (41.7% for a total of 36, 24.2% for a total of 62 species) species were identified as homogenizing with mean number of occurrences 3.8. The correlation between geographic distances and faunal dissimilarities were weak for homogenizing species, and those were higher and positive for native species. This indicates higher spatial turnover of species composition and a distance decay of similarity for native species but not for homogenizing ones. We suggest a term “urban vicariance” to describe faunal elements that are functionally similar, but taxonomically different.