Effects of Elevated CO2 on Foliar Phenolics and Condensed Tannins of Three Tree Species
Kelly, J.J., Bansal, A., Winkelman, J., Janus, L.R., Hell, S., Wencel, M., Belt, P., Kuehn, K.A., Rier, S.T. and Tuchman, N.C. 2010. Alteration of microbial communities colonizing leaf litter in a temperate woodland stream by growth of trees under conditions of elevated atmospheric CO2. Applied and Environmental Microbiology 76: 4950-4959.
From Kelly et al.'s tabular results, it can be calculated that the 360-ppm CO2 increase employed in their study boosted the simple phenolics concentrations of the aspen, maple and willow leaves by 16, 30 and 22%, respectively, while it boosted their condensed tannin concentrations by 60, 85 and 26%, respectively.
Because of the fact that both foliar phenolics and condensed tannins often enhance plant resistance to herbivore and pathogen attack, plus the fact that ruminants browsing on foliage containing condensed tannins may have a tendency to expel less methane (an important greenhouse gas) to the atmosphere, the increased concentrations of these substances in the leaves of trees grown in CO2-enriched air bodes well for the health of the trees themselves and for people concerned about CO2- and methane-induced global warming.