Purdue Climate Change Research Center

Soil-Earthworm-Litter System Controls on the Stabilization of Organic Matter in Forests

Funded by the National Science Foundation

Because soil acts as both a sink and a source for carbon, a detailed, mechanistic understanding of the controls on the conversion of litter organic matter and its subsequent stability in soil is critical to accurately account for the changing balance between the atmospheric, terrestrial plant, and soil carbon reservoirs. Surprisingly, earthworm (EW) activity, with its feedbacks to plant biopolymer alteration, enzymatic activity, and microbial community structure is generally not considered in studies of soil organic matter stabilization.

This project seeks to document and quantify how these protective mechanisms interact in natural and experimental systems impacted by different degrees of EW activity. This year, a preliminary study of EW activity and soil organic dynamics at the research forest at the Smithsonian Environmental Research Center (SERC) has been completed. The study focused on analyzing wood, root, and foliar biopolymer distributions among soil particle fractions to assess the competing controls that inherent plant chemistry, delivery rate, and earthworm activity might have in determining the chemical landscape measured at SERC. The results of the study (Crow et al., 2009) indicate that selective feeding on leaf body tissue by invasive earthworms contributes to a shift in the biopolymer composition of litter residue and that this chemical trajectory persists below ground in soil particulate organic matter (POM). Furthermore, the findings show that stand age, tree species and selective feeding by invasive earthworms all impacted POM composition in different manners, and should be considered together as aspects of forest succession that affect soil carbon chemistry and thus potentially influence carbon stabilization in soil.

Crow, S.E., T. R. Filley, M. McCormick, K. Szlavecz, D. E. Stott, D. Gamblin, G. Conyers, Earthworms, stand age, and species composition interact to influence particulate organic matter chemistry during forest succession. Biogeochemistry, (2009); 92:61-82.

Investigator(s)

Timothy Filley, EAS

Cliff Johnston, Agronomy

Melissa McCormick, Smithsonian Environmental Research Center

Kathy Szlavecz, The Johns Hopkins University

Susan Crow, University of Hawaii

Contact Information

Purdue University
PCCRC
203 S. Martin Jischke Drive
MANN 105
West Lafayette, IN 47907