Exotic Earthworms and North Temperate Forests

image of students coring earthworm burrowsNon-native earthworms introduced to forest ecosystems eliminate organic horizons and homogenize soil profiles through their burrowing activities. By consuming and processing annual leaf litter inputs to the soil, earthworms profoundly alter the soil environment and change the ways in which carbon and nutrients are processed. We are investigating effects of earthworm activities on the processing and retention of carbon and nitrogen in soils of hardwood forests in central New York.

We have found that, in this forest ecosystem, earthworms reduce the amount of C stored in soils but retain more N, compared to nearby earthworm-free soils. Our most recent experiments examine more specifically how earthworms influence the soil microbial community, and whether differences in the soil microbial community correspond with changes in organic carbon metabolism and the stoichiometry of the microbial biomass.

Related publications:

Groffman, P.M., T.J. Fahey, M.C. Fisk, J.B. Yavitt, R.E. Sherman, P.J. Bohlen, and J.C. Maerz. 2015. Earthworms increase soil microbial biomass carrying capacity and nitrogen retention in northern hardwood forests. Soil Biology and Biochemistry 87: 51-58.

Dempsey, M.A., M.C. Fisk, T.J. Fahey, J.B. Yavitt, and T.C. Balser. 2013. Exotic earthworms alter soil microbial community composition and function. Soil Biology and Biochemistry 67:263-270.

Fahey, T.J., J.B. Yavitt, R.E. Sherman, J.C. Maerz, P.M. Groffman, M.C. Fisk, and P.J. Bohlen. 2012. Earthworms, litter and soil carbon in a northern hardwood forest. Biogeochemistry 114: 269-28.

Dempsey, M.A., M.C. Fisk, and T.J. Fahey. 2011. Earthworms increase the ratio of bacteria to fungi in northern hardwood forest soils, primarily by eliminating the organic horizon. Soil Biology and Biochemistry 43: 2135-2141.

Fisk, M.C., T. J. Fahey, P.M. Groffman, and P.J. Bohlen. 2004. Earthworm invasion, fine root distributions and soil respiration in north temperate forests. Ecosystems 7:55-62.

image of earthworm castings