Modeling fungal decomposition pathways across scales
J. M. TALBOT (1), K. G. Peay (1). (1) Boston University, Boston, MA, U.S.A.
Linking community composition to ecosystem function is a central goal of ecology. We tested the hypothesis that functional type of soil fungi is a better predictor of decomposition capability than evolutionary history (i.e. phylogenetic relatedness). To test this hypothesis, we studied measured activity of 10 different extracellular enzymes produced by 55 model species of fungi on sterilized leaf litter in laboratory microcosms. To determine if individual taxa drive decomposition pathways in nature, we plan to compare microcosm data with field data on extracellular enzyme activity and fungal community composition in <i>Pinus</i> dominated soils collected from across North America. Certain decomposition capabilities differed among phylogenetic groups of fungi. Cellobiose-, hemicellulose-, and protein-targeting enzymes all differed significantly among orders of fungi (<i>P</i> = 0.0003, <i>P</i> = 0.0499, <i>P</i> = 0.018, respectively). By contrast, activity of all extracellular enzymes was significantly higher in litter colonized by saprotrophs compared to ectomycorrhizal species. However, within closely related pairs of fungi, species identity was a better predictor of decay capability than functional type (<i>P</i><0.0001). Collectively, our results indicate that while functional type is a better predictor of decomposition niche than phylogenetic relatedness of fungi, species identity is the major determinant of decomposition capability.
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