The Effects Of Ambient Pollutants On The Physiology And Morphology Of Mature Red Spruce

Two stands of red spruce (Picea rubens Sarg.) trees growing in close proximity to each other on Whitetop Mountain in Virginia exhibit varying degrees of decline symptoms. The declining stand experiences higher precipitation and deposition amounts than the healthy stand. Average ozone levels are 50-60 ppb, with rain of pH 4.3 and cloudwater of pH 3.4. In both stands branch chambers were installed on mature trees to exclude ozone and acidic precipitation (filtered) or just acidic precipitation (non-filtered). Unchambered branches were used as controls. Morphological and physiological measurements were made on the branches over the growing season and comparisons were made among treatments for both the healthy and declining stands . . . Future studies should focus on reduced cold hardiness of red spruce as a result of acidic deposition.