Les tourbières se transforment en émetteurs de CO2.

© Photo credits: Kim Worm Sorensen

© Photo credits: Kim Worm Sorensen

Biogeochemical plant–soil microbe feedback in response to climate warming in peatlands.

"Peatlands act as global sinks of atmospheric carbon (C) through the accumulation of organic matter, primarily made up of decay-resistant litter of peat mosses. However, climate warming has been shown to promote vascular plant growth in peatlands, especially ericaceous shrubs. A change in vegetation cover is in turn expected to modify above-ground/below-ground interactions, but the biogeochemical mechanisms involved remain unknown. Here, by selecting peatlands at different altitudes to simulate a natural gradient of soil temperature, the group of Prof. Alexandre Buttler (Ecological Systems Laboratory), in collaboration with researchers of the University of Lancaster, show that the expansion of ericaceous shrubs with warming is associated with an increase of polyphenol content in both plant litter and pore water. In turn, this retards the release of nitrogen (N) from decomposing litter, increases the amount of dissolved organic N and reduces N immobilization by soil microbes. Their data suggest that climate-induced changes in plant cover can reduce the productivity of peat mosses and potentially prime the decomposition of organic matter by affecting the stoichiometry of soil enzymatic activity."

See: Luca Bragazza, Julien Parisod, Alexandre Buttler & Richard D. Bardgett. Nature Climate Change (2012) doi:10.1038/nclimate1781

More:Le Monde - Avec le réchauffement, les tourbières se transforment en émetteurs de CO2.