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SFS Annual Meeting

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The rate at which leaf litter decomposes in streams varies predictably with physical and chemical traits of the litter itself, declining with lignin and tannin concentrations, and increasing with sugars. The rate of litter decomposition is well studied because it is an important ecosystem process. Yet, the simplicity of a single rate to describe litter disappearance masks the variety of fates of the elements the litter contains and the multiple pathways through which they flow. Results from our group suggest that litter traits retarding decomposition disproportionately favor element transfer up the food chain to insect grazers, whereas elements from rapidly decomposing leaves tend to be lost downstream and to the atmosphere. Thus, both the rates and pathways of element flow from decomposing litter are at least equally important for understanding the roles of allochthonous leaves within stream food webs. Our approach using 15N and 13C enables quantitative tracing of element flux from litter through the food web and ecosystem. Here we demonstrate, using 12 leaf species, how leaf litter type affects the relative strength of three pathways of C and N loss rates: leaching, microbial processing, and invertebrate shredding.

Courtney Roush (Primary Presenter/Author), Northern Arizona University,;

Meghan Schrik (Co-Presenter/Co-Author), Northern Arizona University,;

Benjamin Koch (Co-Presenter/Co-Author), Northern Arizona University,;

Egbert Schwartz (Co-Presenter/Co-Author), Northern Arizona University,;

Paul Dijkstra (Co-Presenter/Co-Author), Northern Arizona University,;

Jane Marks (Co-Presenter/Co-Author), Northern Arizona University,;

Adam Wymore (Co-Presenter/Co-Author), University of New Hampshire,;