Living roots magnify the response of soil organic carbon decomposition to temperature in temperate grassland.

Hill, P.W., Garnett, M.H. , Farrar, J. and Jones, D.L. (2015) Living roots magnify the response of soil organic carbon decomposition to temperature in temperate grassland. Global Change Biology, 21(3), pp. 1368-1375. (doi: 10.1111/gcb.12784)

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Increasing atmospheric carbon dioxide (CO2) concentration is both a strong driver of primary productivity and widely believed to be the principal cause of recent increases in global temperature. Soils are the largest store of the world's terrestrial C. Consequently, many investigations have attempted to mechanistically understand how microbial mineralisation of soil organic carbon (SOC) to CO2 will be affected by projected increases in temperature. Most have attempted this in the absence of plants as the flux of CO2 from root and rhizomicrobial respiration in intact plant-soil systems confounds interpretation of measurements. We compared the effect of a small increase in temperature on respiration from soils without recent plant C with the effect on intact grass swards. We found that for 48 weeks, before acclimation occurred, an experimental 3 °C increase in sward temperature gave rise to a 50% increase in below ground respiration (ca.0.4 kg C m−2; Q10=3.5), whereas mineralisation of older SOC without plants increased with a Q10 of only 1.7 when subject to increases in ambient soil temperature. Subsequent 14C dating of respired CO2 indicated that the presence of plants in swards more than doubled the effect of warming on the rate of mineralisation of SOC with an estimated mean C age of ca.8 y or older relative to incubated soils without recent plant inputs. These results not only illustrate the formidable complexity of mechanisms controlling C fluxes in soils, but also suggest that the dual biological and physical effects of CO2 on primary productivity and global temperature have the potential to synergistically increase the mineralisation of existing soil C.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Garnett, Dr Mark
Authors: Hill, P.W., Garnett, M.H., Farrar, J., and Jones, D.L.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Global Change Biology
Publisher:John Wiley & Sons Ltd.
ISSN (Online):1365-2486
Copyright Holders:Copyright © 2014 The Authors
First Published:First published in Global Change Biology 21(3):1368–1375
Publisher Policy:Reproduced under a Creative Commons License
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