Impact of acid fog and ozone on coastal red spruce |
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| Authors: | R Jagels J Carlisle R Cunningham S Serreze P Tsai |
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| Institution: | 1. Department of Forest Biology, University of Maine, 04469, Orono, Maine, U.S.A.
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| Abstract: | High levels of ozone and acidic fog have been measured along the coast of Maine, U.S.A. Some of the ozone and nitrate are a consequence of direct transport from East Coast metropolitan centers, but we discuss evidence supporting N2O5, and perhaps ozone, generation at forested sites from NOx precursors. Fogs with pH below 3.3 occur with greatest frequency in the mid-coast region. Ozone is consistently highest along the southwest coast, but peak hourly averages are often highest in the mid-coast. Historical evidence suggests an increase in fog acidity and nitrate levels, but no change in sulphate within the past 48 years. Red spruce with decline symptoms can be observed from the south-coast to mid-coast region, with the greatest symptom development in the mid-coast. Trees in the mid-coast on soils with high base saturation and Ca/Al ratios develop symptoms of late winter injury (reddening and casting of current year needles in late winter and spring). Trees on poorer soils develop chlorosis on upper surfaces of older needles. Nutrient analysis of soils and foliage reveals differences between stressed and unstressed sites. Scanning electron microscopy of needle surfaces also reveals response differences between pollutant stressed and unstressed trees. Hypotheses and research directions are discussed. |
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