Institute of Ecosystem Studies

2007 BES Annual Meeting Presentation and Poster Abstracts

Effects of earthworm density and species on soil CO2 flux
Xia, Lijun
Co-Authors: Lijun Xia, Katalin Szlavecz, Jerry Burgess, Chris Swan
Abstract: Soil surface CO2 efflux is a major component of the biosphere's carbon cycle, and has a potential role either to amplify global warming due to its sensitivity to environmental conditions. It involves different sets of chemical, physical, and biological processes, which are, in turn, influenced by an array of biotic and abiotic factors. The importance of earthworms in affecting the soil processes and nutrient cycling has long been recognized. However, the overall effects of earthworms on nutrient cycling and CO2 fluxes are not sufficiently studied. To understand the effects of earthworm density and earthworm species on the CO2 flux, we measured CO2 fluxes in a series of mesocosms every five days for a month. We added tulip poplar litter and 0,2,4,8 earthworms to the mesocosms. The earthworm species were either Lumbricus rubellus, Octolasion lacteum (both invasive European species) , or mixture of both. CO2 fluxes increased with the number of earthworms (from around 0.60 mg CO2 per hr with 0 earthworm to around 1.20 mg CO2 per hr with 8 earthworms), but this trend was less obvious with time. CO2 fluxes in mesocosms with Lumbricus rubellus were higher than those either with Octolasion lacteum or with mixed species. Leaf mass loss correlated well with the number of earthworms, but the consumption rates of leaves were generally lower with more earthworms indicating bot intra- and interspecific competition effect. Generally, we detected both density and earthworm species effect on soil CO2 flux, but the mechanisms need further study.