| This dissertation documents the responses by ectomycorrhizal fungi to elevated carbon dioxide (CO2) and ozone O3 within aspen (Populus tremuloides Michx.) and birch (Betula papyrifera Marshall) dominated forests. Research was conducted at the Aspen FACE (Free Air CO2 Enrichment) site near Rhinelander, WI, USA. Northern deciduous forest systems have been exposed to elevated CO2 and O3, alone and in combination, since 1997. The Aspen FACE site has provided a long-term and large-scale field experiment capable of investigating how forest ecosystems will respond to CO2 and O3 levels at levels which will be reached in approximately 50 years. Ectomycorrhizal fungal dynamics under elevated CO2 and O3 were investigated at the sporocarp (fruiting structure), ectomycorrhizal (interface between the fungus and root) and hyphal (vegetative structure) levels, providing an extensive account of responses to elevated CO2 and O3. Ectomycorrhizal fungi were characterized based on productivity, respiration and/or community composition, across multiple years when possible. |
