Early degradation of plant alkanes in soils: a litterbag experiment using C-13-labelled leaves

Than Thuy Nguyen Tu (1) , Céline Egasse (1) , Bernhard Zeller (2) , Gérard Bardoux (3) , Philippe Biron (3) , Jean-François Ponge (4) , Brigitte David (1) , Sylvie Derenne (3)

1 CR2P - Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements
2 BEF - Unité de recherche Biogéochimie des Ecosystèmes Forestiers
3 Bioemco - Biogéochimie et écologie des milieux continentaux
4 MAOAC - Mécanismes adaptatifs : des organismes aux communautés

We monitored the carbon isotope composition of bulk leaves and specific long-chain alkanes during a four-year litterbag experiment using C-13-labelled leaves and unlabelled reference leaves of the European beech tree (Fagus sylvatica L.). Whereas the isotope composition of alkanes from C-13-enriched leaves exhibited a marked decrease in C-13-content, the isotope composition of unlabelled reference leaves remained nearly constant. We interpreted this difference as evidence for a microbial contribution to the long-chain alkane pool of the decomposing leaves and related it to the progressive invasion of leaves by soil organisms which was revealed upon microscopic examination. These results suggest that long-chain alkanes may not provide an unaltered record of organic carbon isotope composition in soils and sediments.

Mots clés: leaf litter decomposition; stable carbon isotopes; lipids; soil organic matter; n-alkanes

Domaines: Science des sols

Than Thuy Nguyen Tu, Céline Egasse, Bernhard Zeller, Gérard Bardoux, Philippe Biron, et al.. Early degradation of plant alkanes in soils: a litterbag experiment using C-13-labelled leaves. Soil Biology and Biochemistry, 2011, 43 (11), pp.2222-2228. ⟨10.1016/j.soilbio.2011.07.009⟩. ⟨hal-00625715⟩