Effects of ambient ozone on the productivity of Populustremuloides Michx. grown under field conditions

Abstract

Field experiments were conducted at a rural site in Millbrook, NY, to measure effects of ambient ozone on saplings of Populustremuloides Michx. Over a 3–year period, four clones representing a range of pollutant sensitivities were exposed to charcoal-filtered and ambient air in open-top chambers. Ambient ozone significantly reduced (12–24%) aboveground dry-matter production and modified tree morphology, root/shoot ratios, and rates of leaf senescence. For two clones, biomass was reduced without visible foliar symptoms. This response raises the possibility of widespread, asymptomatic depression of forest productivity under ambient air pollutant conditions.