Battling for Fungal Sporocarps in Earth's Forests: CO2 vs. O3
Andrew, C. and Lilleskov, E.A. 2009. Productivity and community structure of ectomycorrhizal fungal sporocarps under increased atmospheric CO2 and O3. Ecology Letters 12: 813-822.
In an effort to find some answers, the authors sampled aboveground sporocarps for four years at the Aspen FACE (free-air CO2 enrichment) site near Rhinelander, Wisconsin, USA, which provided, in their words, a "unique opportunity to examine the effects of both elevated CO2 and O3 on a forested ecosystem," which examination was conducted during years 4 through 7 of the aspen and aspen-birch forests' exposures to ambient and enriched concentrations of the two gases: CO2 (350 and 550 ppm) and O3 (33-67 and 50-100 ppb).
The two researchers found that total mean sporocarp biomass "was generally lowest under elevated O3 with ambient CO2," and that it "was greatest under elevated CO2, regardless of O3 concentration." In another place in their paper, they state there was "a complete elimination of O3 effects on sporocarp production when [extra] CO2 was added." And they say they "expect that the responses seen in the present study were conservative compared to those expected under regional to global changes in CO2 and O3."
By itself, or in combination with rising ozone concentrations, the ongoing rise in the air's CO2 content appears destined to enhance the genetic recombination and long-distance dispersal of the ectomycorrhizal fungi that form symbiotic relationships with the roots of aspen and birch trees, thereby positively contributing to various food webs that will be found within aspen and aspen-birch forests of the future.