The Path From Litter to Soil: Insights Into Soil C Cycling From Long‐Term Input Manipulation and High‐Resolution Mass Spectrometry
Persistent URL
Author(s)
Reynolds, Lorien L.
Lajtha, Kate
Bowden, Richard D.
Tfaily, Malak M.
Johnson, Bart R.
Bridgham, Scott D.
Date Issued
May 2018
Abstract
The path of carbon (C) from plant litter to soil organic matter (SOM) is key to understanding how soil C stocks and microbial decomposition will respond to climate change and whether soil C sinks can be enhanced. Long‐term ecosystem‐scale litter manipulations and molecular characterization of SOM provide a unique opportunity to explore these issues. We incubated soils from a 20‐year litter input experiment for 525 days and asked how litter quantity and source (i.e., roots versus aboveground litter) affected C cycling, microbial function, and the size and molecular composition of C pools. Input exclusion led to a 30% loss of soil C, attributable largely to the nonmineral‐associated C fraction, and to declines in soil C decomposition. The absence of roots caused a shift in the microbial catabolic profile, though there was little evidence that root litter was preferentially stabilized. Although C pool size did not change with litter additions, Fourier transform ion cyclotron resonance mass spectrometry analysis of the finest mineral fraction revealed dramatic changes to the chemical composition of carbon. Lipid content increased proportionally with input addition and was subsequently mineralized during incubation, indicating that this fraction was metabolically active. Moreover, nonmetric dimensional scaling showed that both litter treatments and incubation caused the molecular composition of SOM to change. We conclude that the path of C from litter to soil may involve labile pools and root‐driven microbial activity associated directly with SOM in the soil mineral matrix otherwise previously hypothesized to be stable.
Journal
Journal of Geophysical Research-Biogeosciences
Department
Biology
Citation
Reynolds, L.L., Lajtha, K., Bowden, R.D., et al. (2018). The path from litter to soil: Insights into soil C cycling from long‐term input manipulation and high‐resolution mass spectrometry. Journal of Geophysical Research-Biogeosciences, 123(5): 1486-1497. doi:10.1002/2017JG004076
Publisher
American Geophysical Union
Version of Article
Published article
Embargo
This article is available to the public after 11/30/2018
DOI
10.1002/2017JG004076
ISSN
2169-8953
e2169-8961
Rights
This article is published by American Geophysical Union in Journal of Geophysical Research-Biogeosciences (2018) Reynolds, et al. All rights reserved.
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