2000 BES Abstracts

Diversity and abundance of earthworms in urban landscapes

Katalin Szlavecz, Rich Pouyat, Csaba Csuzdi, Mary Valentino

Earthworms can have profound effects on soil characteristics and processes. Their effect can be so great that many soil ecologists consider them keystone species in temperate ecosystems. Urban and suburban areas can provide suitable habitats for earthworms, due to less fluctuating conditions, a variety of food resources and human-assisted dispersal. During 1999 and 2000 we sampled seventeen sites in the greater Baltimore area to assess earthworm community structure and abundance. These sites represented a variety of plant structural patches including forests, grasslands, the transitional zone between them, and an old field. The organisms were expelled from the soil using 0.04% formaldehyde solution. A total of 90 samples were taken. Density and biomass varied between 0 and 278 individuals m-2, and between 0 and 152 g m-2, respectively. The highest values were obtained in one of the urban forests (Leakin Park). Sampling did not yield any organisms on two sites which were both grassy areas. Exotic species dominated all of the communities. Lumbricus terrestris was dominant in Leakin Park, whereas Allolobophora caliginosa was the most numerous species in Hillsdale Park, Baltimore City. The earthworm community on one forest site (Cross Keys along I-83) almost exclusively consisted of Amynthas hilgendorfi, a species introduced from Asia, probably Japan. Although the BES reference site, Oregon Ridge yielded the highest species richness (eight species), the dominant species were the introduced L. rubellus, L. terrestris and A. caliginosa. Besides Oregon Ridge, native species (Diplocardia sp.) were only found in the abandoned agricultural field.