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Temperature sensitivity of soil carbon decomposition

molecular controls and environmental feedbacks

Erhagen, Björn (2013). Temperature sensitivity of soil carbon decomposition. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2013:61
ISBN 978-91-576-7860-7
eISBN 978-91-576-7861-4
[Doctoral thesis]

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The world's soils contain three times as much carbon as the atmosphere. Thus, any changes in this carbon pool may affect atmospheric CO₂ levels with implications for climate change. Anthropogenic contributions to global carbon and nitrogen cycles have increased in the last century. Both temperature and nitrogen influence decomposition processes and are therefore critical in determining CO₂ return to the atmosphere.

Kinetic theory predicts that the chemical composition of soil organic matter
represents a dominant influence on the temperature response of decomposition.
However, empirical observations and modeling indicate that this relationship is
constrained by other factors. We address a number of research questions related to these factors, which are central to a thorough understanding of temperature sensitivity in decomposition. Specifically it offers one of the first empirical observations consistent with modeling in demonstrating increased temperature sensitivity for the uptake of carbon monomers over microbial cell membranes. Using NMR spectroscopy we were able to demonstrate how temperature response is directly related to the chemical composition of the organic material present. The thesis shows how increased soil nitrogen reduces temperature response. The key mechanism behind this observation, we suggest, is the influence of nitrogen on the chemical composition of organic matter, mediating a direct effect on temperature response. Given that nitrogen availability in terrestrial ecosystems has doubled relative to preindustrial levels, this observation may be vital in understanding the net effect of temperature increase on CO₂ return to the atmosphere. The proportion of carbon in plant litter transformed by microorganisms into biomass (carbon use efficiency; CUE) is a central factor determining global land-atmosphere CO₂ exchange. CUE was highly sensitive to
whether carbon monomers or polymers were degraded; yet temperature had no clear effect on CUE. The majority of soil organic matter is comprised of polymers,
highlighting the importance of using these as model substrates in studies of CUE.

This thesis represents a major contribution to our understanding of the intrinsic and external controls acting on temperature sensitivity of decomposition, and thus to regulation of CO₂ return to the atmosphere under a changing climate.

Authors/Creators:Erhagen, Björn
Title:Temperature sensitivity of soil carbon decomposition
Subtitle:molecular controls and environmental feedbacks
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :11 November 2013
Number of Pages:68
I.Erhagen, B., Ilstedt, U. and Nilsson, M.B. Temperature sensitivity of saprotrophic CO2 production increases with increasing carbon substrate uptake rate (under review, Soil Biology & Biochemistry).
II.Erhagen, B., Öquist, M., Sparrman, T., Haei, M., Ilstedt, U., Hedenström, M., Schleucher, J. and M.B. Nilsson. (2013). Temperature response of litter and soil organic matter decomposition is determined by chemical composition of organic material. Global Change Biology 19(11), 12342.
III.Nilsson, M.B., Erhagen, B. Ilstedt, U., Sparrman, T., Öquist, M, and J. Schleucher. Increased nitrogen availability counteracts the climatic changes feedback from increased temperature on boreal forest soil organic matter degradation. (Manuscript).
IV.Erhagen, B., Haei, M., Öquist, M., Schleucher, J. Sparrman, T. and Nilsson, M. B. The effect of temperature and substrate quality on carbon use efficiency of saprotrophic decomposition. (Manuscript).
Place of Publication:Umeå
Publisher:Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-7860-7
ISBN for electronic version:978-91-576-7861-4
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:P Natural resources > P34 Soil biology
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 104 Chemical Sciences > Organic Chemistry
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Biochemistry and Molecular Biology
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
Agrovoc terms:degradation, soil organic matter, temperature, carbon dioxide, plant litter, carbon cycle, nitrogen cycle, nmr spectroscopy, models, boreal forests, sweden
Keywords:decomposition, soil organic matter, litter, boreal forest, organic chemical composition, temperature sensitivity, Q10, CUE, CP- MAS NMR, HSQC
Permanent URL:
ID Code:10893
Department:(S) > Dept. of Forest Ecology and Management
Deposited By: Björn Erhagen
Deposited On:12 Nov 2013 07:38
Metadata Last Modified:02 Dec 2014 11:04

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