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SFS Annual Meeting

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STOICHIOMETRY, FUNGAL DYNAMICS, AND DECOMPOSITION OF STANDING DEAD EMERGENT MACROPHYTES: A SYNTHESIS OF FIELD STUDIES

The standing dead phase is an important stage of decomposition of emergent vegetation in marshes, yet few studies have examined how intrinsic litter traits constrain standing dead decomposition across plant organ types or species. We synthesized field studies quantifying carbon:nitrogen (C:N), carbon:phosphorus (C:P), and fungal biomass during decomposition of leaf, sheath, and culm tissues of several emergent macrophyte species (Typha, Juncus, Erianthus, and Phragmites). Across 12 datasets, plants resorbed 8-70% N and 15-93% P from living-green to senescence. All tissues exhibited net N mineralization whereas some tissues showed P immobilization during decomposition. Lower-C:N tissues exhibited greater decomposition rates (r=-0.80, P<0.01) and greater proportional N mineralization (r=-70, P<0.05). Tissue C:P was also negatively related to decomposition rates (r=-0.73, P<0.01) whereas tissue C:P was only weakly related to P mineralization (r=-0.36, P=0.251). Estimated fungal C use efficiencies ranged from 0.006 to 0.233 but were not related to tissue stoichiometry. A stoichiometric model of litter decomposition estimated critical C:N and C:P ratios and predicted most tissues begin N and P mineralization immediately after senescence. Our study will improve prediction of the fates of C and nutrients in standing dead vegetation across marsh ecosystems.

Tori Hebert (Primary Presenter/Author), University of Southern Mississippi, tori.hebert@usm.edu;


Halvor Halvorson (Co-Presenter/Co-Author), University of Southern Mississippi, halvor.halvorson@usm.edu;


Kevin Kuehn (Co-Presenter/Co-Author), The University of Southern Mississippi, kevin.kuehn@usm.edu;