PARENT SESSION
Oral Session 15: Soil Ecology I: Mycorrhizal Communities.
Presiding: V Borowicz and X He
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 137.
Carbon dioxide and ozone affect production and community structure of ectomycorrhizal fungal communities in the AspenFACE experiment.
Lilleskov, Erik*,1, 1 USDA Forest Service, North Central Research Station, Houghton, MI, USA
ABSTRACT- Humans are dramatically altering atmospheric chemistry at regional and global scales. Elevated carbon dioxide has the potential to increase, and ozone has the potential to decrease, plant C fixation and allocation belowground. The impacts of these gases on the composition, structure and function of mycorrhizal fungal communities are poorly understood. We have initiated work at the AspenFACE site in Rhinelander, Wisconsin, USA to determine whether mycorrhizal fungal communities are altered by these gases. Factorial carbon dioxide and ozone treatments have been applied to stands there in an open-air system since 1997. As a first phase of this work, we are examining treatment effects on EMF communities measured as sporocarp production and on root tips. We hypothesized that treatments would alter sporocarp production in parallel with effects on belowground C allocation, and alter EMF communities to fungi with greater (carbon dioxide treatment) or lesser (ozone treatment) C demands. Initial results of this work from aspen and aspen-birch stands suggest that sporocarp production is significantly reduced in response to elevated ozone. Although carbon dioxide alone led to elevated sporocarp biomass in the aspen-birch section in 2003, positive carbon dioxide effects were much stronger in the presence of ozone. Ozone treatment caused dramatic reductions of sporocarps of strongly rhizomorphic taxa with larger sporocarps (especially Leccinum), but not of less rhizomorphic taxa with smaller sporocarps (Inocybe, Hebeloma, Laccaria). We are in the process of analyzing root samples to determine whether these patterns are reflected belowground. Changes in sporocarp production of this magnitude could have significant impacts on fungal-based food webs.
Key words: ozone, community structure, carbon dioxide, ectomycorrhizal fungi