Effects of short-term ecosystem experimental warming on water-extractable organic matter in an ombrotrophic Sphagnum peatland (Le Forbonnet, France)
2011
Delarue, Frédéric | Laggoun-Défarge, Fatima | Buttler, Alexandre | Gogo, Sébastien | Jassey, Vincent | Disnar, Jean-Robert | Institut des Sciences de la Terre d'Orléans (ISTO) ; Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS) | Laboratoire des systèmes écologiques (ECOS) ; Ecole Polytechnique Fédérale de Lausanne (EPFL) | Laboratoire Chrono-environnement (UMR 6249) (LCE) ; Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC) ; Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC) | WSL Lausanne ; WSL | Unité de Science du Sol (Orléans) (URSols) ; Institut National de la Recherche Agronomique (INRA) | ANR-07-VULN-0010,PEATWARM,Impact du réchauffement climatique sur la focntion de puits de carbone de l'ecosysteme tourbières à sphaignes.(2007)
International audience
Afficher plus [+] Moins [-]anglais. In a future warmer world, peatlands may change from a carbon sink function to a carbon source function. This study tracks changes in water-extractable organic matter (WEOM) after one year of in situ experimental warming using open top chambers (OTCs). WEOM was studied in the upper peat layers (0-10 cm) through analysis of water-extractable organic carbon (WEOC), stable C isotopic composition (δ13C), specific UV absorbance at 280 nm and sugar composition of cores taken from an open bog (DRY sites) and a transitional poor fen (WET sites). At the DRY sites, the impact of OTCs was weak with respect to WEOM parameters, whereas at the WET sites, the air warming treatment led to a decrease in peat water content, suggesting that the supply of heat by OTCs was used mainly for evapotranspiration. OTCs at the WET sites also induced a relative enrichment at the surface (0 to 5 cm depth) of aliphatic and/or aromatic compounds with concomitant decrease in WEOC, as a result of decomposition. On the contrary, WEOC and sugar content increased in the deeper peat layer (7.5-10 cm depth) probably as a result of increased leaching of phenolic compounds by roots, which then inhibits microbial activity. The different response to experimental warming at DRY and WET sites suggests that the spatial variability of moisture in is critical for understanding of the impact of global warming on the fate of OM and the carbon cycle in peatlands.
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