The role of invasive earthworm activity on the chemical alteration trajectory of forest litter

GEOC 50

Timothy R. Filley, filley@purdue.edu, Department of Earth and Atmospheric Sciences, Purdue University, 550 Stadium Mall Dr, West Lafayette, IN 47907, Susan Crow, susanecrow@googlemail.com, 14CHRONO Centre for AMS, Queen's University, University Road, Belfast, BT7 1NN, United Kingdom, Cliff T. Johnston, clays@purdue.edu, Crop, Soil and Environmental Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, Melissa McCormick, mccormickm@si.edu, Smithsonian Environmental Research Center, Contes Warf Rd, Edgewater, MD, and Katalin Szlavecz, Dept. of Earth and Planetary Sciencesý, The Johns Hopkins Universityý, Baltimore, MD ý21218-2681ý.
To determine control of earthworm activity on leaf litter biopolymer dynamics we analyzed the residues of Tulip poplar leaves after six months of decay, comparing open surface litter and litter bag experiments within plots that varied non-native earthworm density and biomass. The chemical alteration of biopolymers was tracked with FTIR spectroscopy, 13C-TMAH thermochemolysis, and alkaline CuO extraction. Additionally, the specific enzyme activities were tracked in surface soils. Earthworm activity resulted in residues depleted in cuticular aliphatic components and polyphenols but were highly enriched in ether-linked lignin with respect to initial litter material. Surface decay in low earthworm abundance plots, as well as all experiments with earthworm-excluding litter bags, resulted in enrichment in aliphatics and only minor increases in ether-linked lignin phenols. All litter exhibited a decline in cinnamyl, ester linked, lignin. The results from litter bag decays were only reflective of the chemical alteration trajectory, i.e. the decomposition pathway from initial amendment, exhibited in surface decay at sites with very low earthworm abundances indicating decay was controlled by the background microbial activity.
 

The David J. Clifford Memorial Symposium
1:30 PM-3:45 PM, Tuesday, August 21, 2007 Boston Park Plaza -- St. James Rm, Oral

Sci-Mix
8:00 PM-10:00 PM, Monday, August 20, 2007 BCEC -- Exhibit Hall - B2, Sci-Mix

Division of Geochemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007