Le Priming Effect dans le sol : mécanismes, acteurs et conséquences sur les services écosystémiques dans un contexte de changement global

The priming effect (PE) is a key mechanism contributing to the carbon balance of the soil ecosystem. Almost 100 years of research since its discovery in 1926 have led to a rich body of scientific publications to identify the drivers and mechanisms involved. A few review articles have summarised the acquired knowledge; the last major one was published in 2010. Since then, knowledge on the soil microbial communities involved in PE and in PE + C sequestration mechanisms has been considerably renewed.This article reviews current knowledge on soil PE to state to what extent new insights may improve our ability to understand and predict the evolution of soil C stocks. We propose a framework to un…

Dynamics and identification of soil microbial populations actively assimilating carbon from 13C-labelled wheat residue as estimated by DNA- and RNA-SIP techniques.

International audience; This work is the first report on the use of DNA-, RNA-SIP approaches to elucidate the dynamics and the diversity of bacterial populations actively assimilating C derived from plant residues labelled at more than 90% (13)C. Wheat-residues, were incorporated and incubated into soil microcosms for 28 days. At the end of the incubation time, no more than 55% of the total CO(2) released was (13)C-labelled, suggesting the occurrence of an important priming effect process. After 7 days, more than 30% of the whole DNA extracted were labelled, allowing an efficient separation of labelled from unlabelled DNA using density gradient centrifugation. The genetic structure of bacte…

Do tropical soil engineer stimulate the bacterial communities link to N2O emission?

National audience

L’usage des terres et les pratiques agricoles contrôlent la minéralisation du C par l’intermédiaire de la biomasse bactérienne et de quelques familles fongiques clés.

High microbial diversity promotes soil ecosystem functioning

ABSTRACT In soil, the link between microbial diversity and carbon transformations is challenged by the concept of functional redundancy. Here, we hypothesized that functional redundancy may decrease with increasing carbon source recalcitrance and that coupling of diversity with C cycling may change accordingly. We manipulated microbial diversity to examine how diversity decrease affects the decomposition of easily degradable (i.e., allochthonous plant residues) versus recalcitrant (i.e., autochthonous organic matter) C sources. We found that a decrease in microbial diversity (i) affected the decomposition of both autochthonous and allochthonous carbon sources, thereby reducing global CO 2 e…

Contamination of soil by copper affects the dynamics, diversity, and activity of soil bacterial communities involved in wheat decomposition and carbon storage.

ABSTRACT A soil microcosm experiment was conducted to evaluate the influence of copper contamination on the dynamics and diversity of bacterial communities actively involved in wheat residue decomposition. In the presence of copper, a higher level of CO 2 release was observed, which did not arise from greater wheat decomposition but from a higher level of stimulation of soil organic matter mineralization (known as the priming effect). Such functional modifications may be related to significant modifications in the diversity of active bacterial populations characterized using the DNA stable-isotope probing approach.

Change in nitrate reducer community structure in wheat residue amended soil revealed by stable isotope probing