PARENT SESSION
Poster Session #25: Mycorrhizal Fungi and Root Processes.
Tuesday, August 6. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

The influence of elevated atmospheric carbon dioxide on community diversity and structure of ectomycorrhizal fungi.

Parrent, Jeri^*,1, Jackson, Jason¹, Moncalvo, Jean-Marc¹, Morris, William¹, Vilgalys, Rytas¹, ¹ Duke University, Durham, NC

ABSTRACT- Ectomycorrhizal fungi (EMF) are the dominant members of the soil fungal community in temperate forests, and will therefore influence carbon sequestration and forest productivity as atmospheric CO₂ concentrations rise. Consequently, we need to understand how the EMF community will change if we are to predict changes in ecosystem function. Because elevated CO₂ increases fine root exudation and production, EMF community diversity may increase due to greater substrate availability. Alternatively, increased demands of host trees for mineral nutrients (N &P) at higher CO₂ concentrations may lead to changes in the EMF with which they associate, eliminating or reducing the abundance of some fungal species. To test these competing hypotheses we used DNA sequence-based methods to compare community diversity and structure between elevated and ambient CO₂ plots of the Free Air CO₂ enrichment (FACE) experiment at Duke University. Sequences of the ITS region of the rDNA were generated to determine species identity using fruiting bodies and root tips sampled from soil cores. A total of 62 EMF species were identified from fruiting bodies across plots, with increased diversity detected under elevated CO₂. However, fruiting body diversity and root tip diversity are often not congruent; we report on differences in species diversity and abundance between CO₂ treatments from these samples. An outstanding question is how these differences in diversity of EMF affect long term forest productivity.

KEY WORDS: Ectomycorrhizae, CO2, diversity, fungi