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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, G01027, doi:10.1029/2007JG000542, 2008

Comparison of the chemical alteration trajectory of Liriodendron tulipifera L. leaf litter among forests with different earthworm abundance

Timothy R. Filley

Department of Earth and Atmospheric Sciences and the Purdue Climate Change Research Center, Purdue University, West Lafayette, Indiana, USA


Melissa K. McCormick

Smithsonian Environmental Research Center, Edgewater, Maryland, USA


Susan E. Crow

Department of Earth and Atmospheric Sciences and the Purdue Climate Change Research Center, Purdue University, West Lafayette, Indiana, USA


Katalin Szlavecz

Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, Maryland, USA


Dennis F. Whigham

Smithsonian Environmental Research Center, Edgewater, Maryland, USA


Cliff T. Johnston

Department of Agronomy (Crop, Soil, and Environmental Sciences), Purdue University, West Lafayette, Indiana, USA


Ronald N. van den Heuvel

Smithsonian Environmental Research Center, Edgewater, Maryland, USA


Abstract

To investigate the control of earthworm populations on leaf litter biopolymer decay dynamics, we analyzed the residues of Liriodendron tulipifera L. (tulip poplar) leaves after six months of decay, comparing open surface litter and litter bag experiments among forests with different native and invasive earthworm abundances. Six plots were established in successional tulip poplar forests where sites varied in earthworm density and biomass, roughly 4–10 fold, of nonnative lumbricid species. Analysis of residues by diffuse reflectance Fourier transform infrared spectroscopy and alkaline CuO extraction indicated that open decay in sites with abundant earthworms resulted in residues depleted in cuticular aliphatic and polysaccharide components and enriched in ether-linked lignin relative to open decay in low earthworm abundance plots. Decay within earthworm-excluding litter bags resulted in an increase in aliphatic components relative to initial amendment and similar chemical trajectory to low earthworm open decay experiments. All litter exhibited a decline in cinnamyl-based lignin and an increase in nitrogen content. The influence of earthworm density on the chemical trajectory of litter decay was primarily a manifestation of the physical separation and concentration of lignin-rich and cutin-poor petioles with additional changes promoted by either microorganisms and/or mesofauna resulting in nitrogen addition and polysaccharide loss. These results illustrate how projected increases in invasive earthworm activity in northern North American forests could alter the chemical composition of organic matter in litter residues and potentially organic matter reaching the soil which may result in shifts in the aromatic and aliphatic composition of soils in different systems.

Received 2 July 2007; accepted 10 December 2007; published 26 March 2008.

Keywords: lignin; earthworm; litter; cutin; decomposition.

Index Terms: 0428 Biogeosciences: Carbon cycling (4806); 0432 Biogeosciences: Contaminant and organic biogeochemistry (0792); 0439 Biogeosciences: Ecosystems, structure and dynamics (4815); 0448 Biogeosciences: Geomicrobiology; 0469 Biogeosciences: Nitrogen cycling.

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Citation: Filley, T. R., M. K. McCormick, S. E. Crow, K. Szlavecz, D. F. Whigham, C. T. Johnston, and R. N. van den Heuvel (2008), Comparison of the chemical alteration trajectory of Liriodendron tulipifera L. leaf litter among forests with different earthworm abundance, J. Geophys. Res., 113, G01027, doi:10.1029/2007JG000542.