Multiplicity of Fungal Form and Function in Arctic-Alpine Ecosystems
Hobbie, Erik A. .
Linking Ectomycorrhizal Species Composition to Belowground Function and Exploration Types.
Mycologists have devoted considerable effort to mapping species composition of ectomycorrhizal communities using newly available genetic techniques but how this newly discovered diversity relates to function has been understudied. The functional attribute of how ectomycorrhizal fungi explore the soil (termed exploration type) is probably conserved within taxa and may provide a useful framework by which to relate diversity to functionality. Analyses of carbon and nitrogen isotopic ratios in sporocarps bodies are proving to be a useful integrator of functional information about the role of different taxa in carbon and nitrogen cycling, the extent of hyphal development, and where in the soil profile specific taxa operate. In the Arctic, the low level of nutrient availability should favor exploration types evolved for transport of patchily distributed resources through hydrophobic rhizomorphs, such as long-distance (e.g., Leccinum ), medium-distance mat (e.g., Hydnellum), and medium-distance fringe (e.g., Cortinarius) exploration types. These types in general require higher hyphal biomass. In contrast, exploration types with hydrophilic mycorrhizae, such as medium-distance smooth (e.g., Amanita), short-distance (e.g., Inocybe), and contact (e.g., Hygrophorus) exploration types should be at a competitive disadvantage since they rely on labile, mobile forms of nitrogen and generally have poor enzymatic capabilities to access other nitrogen forms. Here, we compared isotopic patterns and compositional data for ectomycorrhizal fungi from Greenland, northern Sweden, and Alaska in arctic and subarctic environments. Lower productivity environments appeared to support a lower proportion of high biomass exploration types, although high biomass exploration types dominate arctic environments. Nitrogen isotope patterns corresponded to exploration type, with long-distance and medium-distance fringe higher in 15N than short-distance, medium-distance smooth, and contact exploration types. Medium-distance mat types were underrepresented relative to more temperate systems, presumably because of the limited contribution of fungi inhabiting the mineral soil in permafrost regions.
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1 - University of New Hampshire, Complex Systems Research Center, Morse Hall, Durham, NH, 03824, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Ballroom 3/Cliff Lodge - Level B
Date: Tuesday, July 28th, 2009
Time: 8:45 AM