Watershed-scale responses to ozone events in a Pinus strobus L. plantation

High O₃ levels during the 1984 growing season in the southern Appalachian Mountains caused extensive damage to a 28 yr old white pine plantation on a 13.4 ha watershed at the Coweeta Hydrologic Laboratory. Ozone stress effects included premature senescence and loss of foliage, stimulation of pine seedling germination, reduced basal area increment, and small but measurable increases in NO₃^–-N and K⁺ concentrations in stream water. There were no observable effects of O₃ damage on nutrient concentrations of stemwood and foliage but net nutrient accumulation was reduced due to lower stemwood production. Ozone injury did not predispose trees to root pathogens or bark beetle infestations.