Leaf size and surface characteristics of Betula papyrifera exposed to elevated CO₂ and O₃

Abstract

Betula papyrifera trees were exposed to elevated concentrations of CO₂ (1.4 x ambient), O₃ (1.2 x ambient) or CO₂ + O₃ at the Aspen Free-air CO₂ Enrichment Experiment. The treatment effects on leaf surface characteristics were studied after nine years of tree exposure. CO₂ and O₃ increased epidermal cell size and reduced epidermal cell density but leaf size was not altered. Stomatal density remained unaffected, but stomatal index increased under elevated CO₂. Cuticular ridges and epicuticular wax crystallites were less evident under CO₂ and CO₂ + O₃. The increase in amorphous deposits, particularly under CO₂ + O₃, was associated with the appearance of elongated plate crystallites in stomatal chambers. Increased proportions of alkyl esters resulted from increased esterification of fatty acids and alcohols under elevated CO₂ + O₃. The combination of elevated CO₂ and O₃ resulted in different responses than expected under exposure to CO₂ or O₃ alone.

Citation

Riikonen, Johanna; Percy, Kevin E.; Kivimaenpaa, Minna; Kubiske, Mark E.; Nelson, Neil D.; Vapaavuori, Elina; Karnosky, David F. 2010. Leaf size and surface characteristics of Betula papyrifera exposed to elevated CO₂ and O₃. Environmental Pollution. 158(4): 1029-1035.