PARENT SESSION
Wednesday, August 9, 1:30-5:00 pm
COS 74 - Mycorrhizal ecology
Heritage Ballroom I, Marriott
Presiders: J Sharma
Ectomycorrhizal community structure and ecosystem functioning across a natural N deposition gradient.
Lucas, Richard*,1, Casper, Brenda1, 1 University of Pennsylvania, Philadelphia, PA, USA
ABSTRACT- Ectomycorrhizal fungi live in association with most tree species of boreal and temperate ecosystems and are important contributors to many ecosystem functions. Previous work in boreal systems suggests that the availability of organic and inorganic nitrogen (N) resources are important contributing factors structuring belowground communities of ectomycorrhizal fungi. We do not yet understand the importance or the implications of changes in the ectomycorrhizal community as measured by effects on forest ecosystems or ecosystem functions such as N cycling or carbon storage. We examined ectomycorrhizal community structure morphologically over a natural atmospheric N deposition gradient across the northeastern United States. We also measured peroxidase, phenol oxidase, and general proteolytic activity, three ecosystem functions in which ectomycorrhizal fungi are involved. Using principle components analysis (PCA), we found significant differences in ectomycorrhizal communities across the gradient with the first three axes describing 38% of the observed variation. Most community differences are driven by the relative abundance of 17 morphotypes across the gradient. Peroxidase and phenol oxidase activity were both significantly lower (p = 0.0323 and 0.0342 respectively) in areas of high atmospheric N deposition. Our data support the hypothesis that with increased atmospheric N deposition ectomycorrhizal communities shift from those using more organic forms of N to those using more inorganic forms of N. Such changes in the ectomycorrhizal community should have important consequences on ecosystem functioning in temperate forest systems.
Key words: ectomycorrhizal fungi, phenol oxidase activity, atmospheric N deposition