Abstract:
We assessed earthworm species composition and abundance during secondary succession at the Smithsonian Environmental Research Center, Maryland, USA. Land use history is well known at this site. Adjacent forest stands of different ages and other vegetation patches were sampled in 1998-99 and in 2006. Out of the 12 species three (Eisenoides loennbergi, Bimastos palustris, Diplocardia caroliniana) were native, the rest were European peregrine earthworms. Native species were mainly found in mature forests, otherwise the species composition of mature and successional stands was similar. Earthworm density and biomass was significantly higher in the successional forests, than in the mature forests, and this pattern appears to be stable at a decadal time scale. Two smaller stands that have never been clearcut did not harbor any earthworms. The forest floor on these sites had a thick organic layer, moder humus and low pH. Bulk density was highest in the youngest (50-70 years) forests. It appears that as the forests enter to a late successional stage (150 years), they no longer can support high abundance of litter feeding earthworms.
