Priming of soil organic matter decomposition scales linearly with microbial biomass response to litter input in steppe vegetation
Xiao, Chunwang (Chinese Academy of Sciences. State Key Laboratory of Vegetation and Environmental Change)
Guenet, Bertrand (University of Antwerp. Research Group of Plant and Vegetation Ecology)
Zhou, Yong (Chinese Academy of Sciences. State Key Laboratory of Vegetation and Environmental Change)
Su, Jiaqi (Chinese Academy of Sciences. State Key Laboratory of Vegetation and Environmental Change)
Janssens, Ivan (University of Antwerp. Research Group of Plant and Vegetation Ecology)

Data:	2015
Resum:	Fresh plant litter inputs accelerate soil organic matter (SOM) decomposition through a ubiquitous mechanism called priming. Insufficient priming has been suggested as a stabilization mechanism of SOM at depth, as well as the long-term persistence of some highly degradable organic compounds in soils. Priming therefore plays a crucial, albeit unquantified and commonly neglected, role in the global carbon cycle. Because priming intensity is likely to be altered by global changeinduced changes in net primary productivity, it casts substantial uncertainty to future projections of the climate-carbon cycle feedback. Using results from a large field litter manipulation experiment in Mongolian steppe, we here show that priming intensifies with increasing litter inputs, but at a decreasing efficiency: the stimulation per unit litter added declines with increasing litter inputs. This non-linear behavior originates from two antagonistic responses to fresh litter inputs: a stimulation of microbial activity versus a shift in microbial community composition (more fungi) associated to substrate shift from SOM to litter. Despite all complexity, however, the priming effect on SOM decomposition scaled linearly with the response of microbial biomass across the entire range of plant litter addition (60-480 g C m⁻²), suggesting that priming could be modeled effectively as a function of the response of microbial biomass to litter inputs. Incorporating the priming mechanism in Earth System models will improve their estimates of the SOM-climate feedback and appears to be best addressed by explicitly representing microbial biomass in the models.
Ajuts:	European Commission 226701 European Commission 31370462 European Commission 610028
Nota:	Research Funding: 'Strategic Priority Research Program - Climate Change: Carbon Budget and Related Issues' of the Chinese Academy of Sciences. Grant Number: XDA05050407. The National Natural Science Foundation of China. Grant Number: 31370462. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences. The Flemish National Science Foundation. The European Community's Seventh Framework Programme (FP7/2007-2013). Grant Number: 226701 (CARBO-Extreme). The European Research Council Synergy. Grant Number: 610028. The Cost Action Terrabites. Grant Number: ES-0805.
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Publicat a:	Oikos, Vol. 124, Issue 5 (May 2015) , p. 649-657, ISSN 1600-0706

DOI: 10.1111/oik.01728

33 p, 2.1 MB

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