There were no observable effects of O3 damage on nutrient concentrations of stemwood and foliage, but net nutrient accumulation was reduced because of lower stemwood production. Ozone injury did not predispose trees to root pathogens or bark beetle infestations. Although there is no long-term trend of change in precipitation chemistry in the Coweeta Basin, streams appear to be in the initial stages of acidification with increased sulfate concentration and anion deficit and decreased concentrations of bicarbonate and calcium. Watershed at higher elevation receive greater precipitation and sulfate deposition, and exhibit higher streamflow.
Soils are potential for sulfate absorption is reduced.
Lower temperatures at high elevations result in reduced rates of microbial sulfate incorporation into organic matter and reduced c flow through the forests. These differences imply that high elevation forests and streams are more susceptible to acidic precipitation. Soils research at Coweeta has emphasized microbial and faunal processes controlling mobility of elements in the forest floor, and biotic controls over decomposition and mineralization. Because of our interest in atmospheric deposition, particular attention has been given to sulfate absorption and incorporation of S into organic matter. Experiments are clarifying mechanisms by which Coweeta forests accumulate sulfate from precipitation, a phenomenon we have documented with our long-term record of precipitation and streamwater chemistry.