K. B. Kouterick

TL;DR: Local ozone concentration and visible foliar injury were measured over the 1994 growing season on open-grown black cherry trees of varying size (age) within forest stands and adjacent openings at a site in north-central Pennsylvania to determine the correlation between visible and physiological injury and ozone exposure.

Abstract: Leaf gas exchange and xylem water potentials were measured in the field throughout the 1994 growing season on leaves in the upper crown of seedling, sapling, and forest canopy black cherry trees (Prunus serotina Ehrh.) in northcentral Pennsylvania. Rates of gas exchange and xylem water potentials generally decreased with increasing tree size. Rates of dark respiration also decreased with increasing tree size. Differences among tree size classes were consistent throughout the growing season for xylem water potentials, but not for leaf gas exchange measurements. In May and June, seedling net photosynthesis and stomatal conductance were approximately 2 x that of larger trees, but their values tended to be similar to or lower than those of larger trees in July and August. Averaged over the entire season, seedlings had higher leaf gas exchange rates than saplings, which had higher rates than canopy trees. Regardless of tree size, stomatal conductance and net photosynthetic rates reached a maximum near mid to late morning. Stomatal conductance and net photosynthesis decreased steadily during the afternoon for larger trees, but seedling rates remained high until late afternoon. Seedlings consistently had the highest predawn and midday xylem water potentials and leaf-to-air water vapor pressure deficits, while canopy trees had the lowest. The results of this study indicate that tree size is an important factor influencing foliar gas exchange and water relations. For. Sci. 42(3):359-365.

TL;DR: Although R-12 had the most severe foliar ozone injury, this family had significantly greater stem volume growth and total final biomass than MO-7 and NS seedlings and growth response following three growing seasons.

TL;DR: Two black cherry families differing in sensitivity to ozone (O(3)) were used to test the hypothesis that leaf morphology is related to foliar sensitivity to O(3), with significantly greater stomatal density and lower ratio of palisade to spongy mesophyll layer.