Ozone Tolerance in New Jersey Field-Grown Eastern White Pine
J. Eberhardt, E. Brennan, J. Kuser and R. Harkov
Abstract: To determine the response of eastern white pine (Pinus strobus) to ambient ozone pollution, a test plot of 1,200 trees (5-7 years old) representing 63 seed sources was evaluated for ozone-induced needle injury in New Brunswick, New Jersey. A subset of trees from 19(1984) and 27 (1985, 1986) selected seed sources was treated with an antioxidant N-[2-(2-oxo-1-imidazolidinyl) ethyl]-N' phenylurea, or left untreated to compare the relative injury in O3-protected and unprotected needles. During the growing season, the national ambient air quality standard O, of 0.12 ppm was exceeded for 43 hrs in 1985, 25 hrs in 1984, and 12 hrs in 1986. Symptoms generally attributed to ozone pollution such as chlorotic mottling and tipburn were observed on 28% to 36% of the trees in a varying number of seed sources, depending on the year. The frequency of each type of symptom and the age of needle affected varied from year to year, but the amount of injury was always low, affecting a maximum of 5 to 10% of the needle area. There was evidence that the observed injury symptoms might not have all been O3-induced. Antioxidant treatment did not reduce the incidence or severity of injury; the occurrence of injury to white pine did not coincide with injury to Og-sensitive Bel W3 tobacco; and mite feeding and water stress were implicated as possible causes of the observed mottling and tip necrosis. The results are contrary to the more widely held view that eastern white pine is sensitive to O3 pollution. Support could be found in the literature for the position that white pine is not sensitive to O3 perse at concentrations that occur in the northeastern U.S.
Keywords: Ethylendiurea (EDU); Pinus strobus