INCREASED LEVELS OF AIRBORNE FUNGAL SPORES IN RESPONSE TO POPULUS-TREMULOIDES GROWN UNDER ELEVATED ATMOSPHERIC CO2

Soil fungi are important components of terrestrial ecosystems. They fu nction as decomposers, pathogens, parasites, and mutualistic symbionts . Their main mode of dispersal is to liberate spores into the atmosphe re. In this study we tested the hypothesis that a higher atmospheric C O2 concentration will induce greater sporulation in common soil fungi, leading to higher concentrations of fungal propagules in the atmosphe re. In our field experiment, the concentration of airborne fungal prop agules, mostly spores, increased fourfold under twice-ambient CO2 conc entrations. Analysis of decomposing leaf litter (likely the main sourc e of airborne fungal propagules) indicated that the fungi produced fiv efold more spores under elevated CO2. Our results provide evidence tha t elevations in atmospheric CO2 concentration can directly affect micr obial function, which may have important implications for litter decay , fungal dispersal, and human respiratory health.