Coupled carbon and nitrogen losses in response to seven years of chronic warming in subarctic soils
Marañón Jiménez, Sara (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Richter, Andreas (Universität Wien. Department of Microbiology and Ecosystem Science)
Sigurdsson, Bjarni D. (Agricultural University of Iceland)
Fuchslueger, Lucia (University of Antwerpen. Department of Biology)
Leblans, Niki I. W. (Universiteit Antwerpen. Departement Biologie)
Janssens, Ivan (University of Antwerp. Department of Biology)
Universitat Autònoma de Barcelona

Data:	2019
Resum:	Increasing temperatures may alter the stoichiometric demands of soil microbes and impair their capacity to stabilize carbon (C) and retain nitrogen (N), with critical consequences for the soil C and N storage at high latitude soils. Geothermally active areas in Iceland provided wide, continuous and stable gradients of soil temperatures to test this hypothesis. In order to characterize the stoichiometric demands of microbes from these subarctic soils, we incubated soils from ambient temperatures after the factorial addition of C, N and P substrates separately and in combination. In a second experiment, soils that had been exposed to different in situ warming intensities (+0, +0. 5, +1. 8, +3. 4, +8. 7, +15. 9 °C above ambient) for seven years were incubated after the combined addition of C, N and P to evaluate the capacity of soil microbes to store and immobilize C and N at the different warming scenarios. The seven years of chronic soil warming triggered large and proportional soil C and N losses (4. 1 ± 0. 5% °C−1 of the stocks in unwarmed soils) from the upper 10 cm of soil, with a predominant depletion of the physically accessible organic substrates that were weakly sorbed in soil minerals up to 8. 7 °C warming. Soil microbes met the increasing respiratory demands under conditions of low C accessibility at the expenses of a reduction of the standing biomass in warmer soils. This together with the strict microbial C:N stoichiometric demands also constrained their capacity of N retention, and increased the vulnerability of soil to N losses. Our findings suggest a strong control of microbial physiology and C:N stoichiometric needs on the retention of soil N and on the resilience of soil C stocks from high-latitudes to warming, particularly during periods of vegetation dormancy and low C inputs.
Ajuts:	European Commission 291780 European Commission 676108 European Commission 610028
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Substrate induced respiration ; Microbial biomass ; Temperature increase ; Nitrogen immobilization ; Microbial carbon and nutrients limitation ; Nitrogen loss
Publicat a:	Soil biology and biochemistry, Vol. 134 (July 2019) , p. 152-161, ISSN 0038-0717

DOI: 10.1016/j.soilbio.2019.03.028

Postprint 35 p, 1.1 MB

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