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Title: Vegetation effects on soil organic matter chemistry of aggregate fractions in a Hawaiian forest

Author
item Stewart, Catherine
item NEFF, JASON - University Of Colorado
item AMATANGELO, KATHRYN - University Of Wisconsin
item VITOUSEK, PETER - Stanford University

Submitted to: Ecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2011
Publication Date: 2/9/2011
Citation: Stewart, C.E., Neff, J., Amatangelo, K., Vitousek, P. 2011. Vegetation effects on soil organic matter chemistry of aggregate fractions in a Hawaiian forest. Ecosystems. 14: 382-397.

Interpretive Summary: We examined chemical changes from live plant tissue to soil organic matter (SOM) to determine the persistence of individual plant compounds into soil aggregate fractions. We characterized the tissue chemistry of a slow- (Dicranopteris linearis) and fast-decomposing species (Cheirodendron trigynum) and O- and A- horizon SOM beneath each species using pyrolysis- gas chromatography-mass spectrometry, with and without derivatization. Although the two species’ live tissue had distinctly different chemistry, SOM chemistry was quite similar across soil size fractions (850-590 'm, 590-180 'm, 180-53 'm and <53 'm) but differed significantly between the O- and A-horizons. The O-horizon contained a primarily lignin and polysaccharide biomarkers while the A-horizon was comprised of polysaccharide, unspecific aromatic, and N-derived compounds, indicating considerable microbial processing of plant litter. The soils beneath Cheirodendron inherited greater lipid signal comprised of cutin and suberin biomarkers whereas the soils beneath Dicranopteris contained greater unspecific aromatic biomarker content, possibly derived from plant lignins. The soils beneath both species were more similar to root polysaccharides, lipids, and lignins than aboveground tissue. This study indicates that although plant-derived OM is processed vigorously, species-specific biomarkers and compound class differences persist into these soils either through inherent recalcitrance or mineral-organic matter interactions. These results suggest that differences in plant chemical properties may influence soil development even after considerable reworking of plant litter by microorganisms.

Technical Abstract: We examined chemical changes from live plant tissue to soil organic matter (SOM) to determine the persistence of individual plant compounds into soil aggregate fractions. We characterized the tissue chemistry of a slow- (Dicranopteris linearis) and fast-decomposing species (Cheirodendron trigynum) and O- and A- horizon SOM beneath each species using pyrolysis- gas chromatography-mass spectrometry, with and without derivatization. Although the two species’ live tissue had distinctly different chemistry, SOM chemistry was quite similar across soil size fractions (850-590 'm, 590-180 'm, 180-53 'm and <53 'm) but differed significantly between the O- and A-horizons. The O-horizon contained a primarily lignin and polysaccharide biomarkers while the A-horizon was comprised of polysaccharide, unspecific aromatic, and N-derived compounds, indicating considerable microbial processing of plant litter. The soils beneath Cheirodendron inherited greater lipid signal comprised of cutin and suberin biomarkers whereas the soils beneath Dicranopteris contained greater unspecific aromatic biomarker content, possibly derived from plant lignins. The soils beneath both species were more similar to root polysaccharides, lipids, and lignins than aboveground tissue. This study indicates that although plant-derived OM is processed vigorously, species-specific biomarkers and compound class differences persist into these soils either through inherent recalcitrance or mineral-organic matter interactions. These results suggest that differences in plant chemical properties may influence soil development even after considerable reworking of plant litter by microorganisms.