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LABILE AND RECALCITRANT CARBON POOLS DURING LEAF DECOMPOSITION: WHO IS USING WHAT WHEN?

Microbial communities associated with leaf litter have access to carbon pools of varying quality. Recalcitrant pools include substrate and high molecular weight dissolved carbon while low molecular weight dissolved carbon is more labile. Labile carbon availability can affect decomposition of recalcitrant carbon depending on microbial community composition and how the community allocates carbon. The objectives of this pilot study were to detect changes in recalcitrant carbon decomposition with the addition of labile carbon, to identify members of the microbial community using specific carbon pools, and to observe how nitrogen availability influences these dynamics. We inoculated senescent beech leaves with a natural microbial consortium collected from water-filled tree holes and added C13-glucose, ammonium, C13-glucose + ammonium, or deionized water. We used the isotopic signature of carbon dioxide produced to quantify the amount of recalcitrant carbon respired. We used DNA stable isotope probing and Illumina sequencing to identify taxa relying on labeled and unlabeled carbon pools. Preliminary results suggest that glucose addition suppressed respiration of substrate carbon (negative priming effect) but that the degree of suppression lessened over time.

Beth Norman (Primary Presenter/Author), Michigan State University, bcheever@msu.edu;


Edward Walker ( Co-Presenter/Co-Author), Michigan State University, walker@msu.edu;