Geothermally warmed soils reveal persistent increases in the respiratory costs of soil microbes contributing to substantial C losses
Marañón Jiménez, Sara (Universidad de Granada. Departamento de Física Aplicada)
Soong, Jennifer L. (University of Antwerp. Department of Biology)
Leblans, Niki I. W. (Universiteit Antwerpen. Departement Biologie)
Sigurdsson, Bjarni D. (Landbúnaðarháskóli Íslands)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Richter, Andreas (Universität Wien. Institut für Mikrobiologie und Ecosystem Wissenschaft)
Asensio, Dolores (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Fransen, E. (University of Antwerp. StatUa Center for Statistics)

Fecha:	2018
Resumen:	Increasing temperatures can accelerate soil organic matter decomposition and release large amounts of CO₂ to the atmosphere, potentially inducing positive warming feedbacks. Alterations to the temperature sensitivity and physiological functioning of soil microorganisms may play a key role in these carbon (C) losses. Geothermally active areas in Iceland provide stable and continuous soil temperature gradients to test this hypothesis, encompassing the full range of warming scenarios projected by the Intergovernmental Panel on Climate Change for the northern region. We took soils from these geothermal sites 7 years after the onset of warming and incubated them at varying temperatures and substrate availability conditions to detect persistent alterations of microbial physiology to long-term warming. Seven years of continuous warming ranging from 1. 8 to 15. 9 °C triggered a 8. 6-58. 0% decrease on the C concentrations in the topsoil (0-10 cm) of these sub-arctic silt-loam Andosols. The sensitivity of microbial respiration to temperature (Q₁₀) was not altered. However, soil microbes showed a persistent increase in their microbial metabolic quotients (microbial respiration per unit of microbial biomass) and a subsequent diminished C retention in biomass. After an initial depletion of labile soil C upon soil warming, increasing energy costs of metabolic maintenance and resource acquisition led to a weaker capacity of C stabilization in the microbial biomass of warmer soils. This mechanism contributes to our understanding of the acclimated response of soil respiration to in situ soil warming at the ecosystem level, despite a lack of acclimation at the physiological level. Persistent increases in the respiratory costs of soil microbes in response to warming constitute a fundamental process that should be incorporated into climate change-C cycling models.
Ayudas:	European Commission 291780 European Commission 610028 Ministerio de Economía y Competitividad CGL2014-52838-C2-1-R
Derechos:	Tots els drets reservats.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió acceptada per publicar
Materia:	Soil CO2 fluxes ; Q10 ; Soil respiration ; Temperature increase ; Metabolic quotient ; Microbial biomass ; Microbial physiology
Publicado en:	Biogeochemistry, Vol. 138, issue 3 (May 2018) , p. 245-260, ISSN 1573-515X

DOI: 10.1007/s10533-018-0443-0

Post-print 28 p, 1.1 MB

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