Simpson, Nicholas B. , Walker, John , Jumpponen, Ari .
Exposure to increased inorganic nitrogen may irreversibly alter arctic ericoid mycorrhizal communities.
ERICOID mycorrhizas (ErM) convey a distinct advantage to their hosts by accessing nutrient sources from the soil. This advantage is most important in ecosystems where inorganic nitrogen is limited or access to inorganic nitrogen sources is minimal because of competition between soil-inhabiting microbes and plants. While arctic soils have low availability of inorganic nitrogen sources, they often contain relatively high concentrations of organic sources such as free amino acids and more recalcitrant complex polymers. The ecosystem functioning in these heath-dominated arctic regions may be driven by the ErMís ability to utilize these organic forms of nitrogen. Ericoid mycorrhizal fungi vary in their preference for nitrogen sources, even to the point where individuals within a species vary in their abilities to use different nitrogen sources more than do individuals that belong to different species. Fungal individuals from the Toolik Lake LTER in Alaska respond differently to organic nitrogen sources if they are grown for extended periods on media with only an inorganic or on media with only an organic source of nitrogen. The observed trends suggest that increases of available inorganic nitrogen in the soil may change the ErM communities. Such changes in an ErM community may lead to dramatic and irreversible changes of the current heath-dominated ecosystem.
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1 - Kansas State University, Division of Biology, Ackert Hall, Manhattan, Kansas, 66506-4901, USA
2 - Appalachian State University, Department of Biology, Rankin West 270, Boone, North Carolina, 28606, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, August 1st, 2006
Time: 2:15 PM