Earthworm populations of Roosevelt Avenue (Brussels, Belgium): composition, density and biomass

Earthworms were sampled (electric octet method) in the lawn islets of the 2 .5 km long Roosevelt avenue (city of Brussels, Belgium). From a preliminary sampling a total of nine species (five to eight per islet) were found of w hich four (Aporrectodea caliginosa, A. longa, A. rosea and Lumbricus rubell us) were present in all the islets. No insularity effect could be found. A full year sampling was then performed in five selected islets, revealing total density between 89 and 253 individuals/m(2) and biomass between 49 an d 153 g/m(2) (yearly averages). Biomass (but not density) correlated best w ith silt and pH.