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Geothermally warmed soils reveal persistent increases in the respiratory costs of soil microbes contributing to substantial C losses

Geothermally warmed soils reveal persistent increases in the respiratory costs of soil microbes contributing to substantial C losses


Title: Geothermally warmed soils reveal persistent increases in the respiratory costs of soil microbes contributing to substantial C losses
Author: Marañón Jiménez, Sara   orcid.org/0000-0001-9786-3977
Soong, Jennifer   orcid.org/0000-0003-3840-7968
Leblans, Niki   orcid.org/0000-0001-6154-1538
Sigurdsson, Bjarni D.   orcid.org/0000-0002-4784-5233
Penuelas, Josep   orcid.org/0000-0002-7215-0150
Richter, Andreas   orcid.org/0000-0003-3282-4808
Asensio, Dolores   orcid.org/0000-0002-7622-1200
Fransén, Erik A.
Janssens, Ivan   orcid.org/0000-0002-5705-1787
Date: 2018-04-17
Language: English
Scope: 245-260
University/Institute: Landbúnaðarháskóli Íslands
Agricultural University of Iceland
Department: Auðlinda- og umhverfisdeild (LBHÍ)
Faculty of Natural Resources and Environmental Sciences (AUI)
Series: Biogeochemistry;138(3)
ISSN: 0168-2563
1573-515X
DOI: 10.1007/s10533-018-0443-0
Subject: Earth-Surface Processes; Environmental Chemistry; Soil respiration; Microbial physiology; Jarðvegur; Kolefni; Jarðhiti
URI: https://hdl.handle.net/20.500.11815/1266

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Citation:

Marañón-Jiménez, S., Soong, J. L., Leblans, N. I., Sigurdsson, B. D., Peñuelas, J., Richter, A., ... & Janssens, I. A. (2018). Geothermally warmed soils reveal persistent increases in the respiratory costs of soil microbes contributing to substantial C losses. Biogeochemistry, 138(3), 245-260.

Abstract:

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.

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This article is part of the FORHOT project

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