ARTIFICIAL WATERSHED ACIDIFICATION ON THE FERNOW EXPERIMENTAL FOREST,USA

A whole-watershed manipulation project was begun on the Fernow Experim ental Forest in West Virginia, USA, in 1987, with the objective of inc reasing understanding of the effects of acidic deposition on forest ec osystems. Two treatment watersheds (WS9 and WS3) and one control water shed (WS4) were included. Treatments were twice-ambient N and S deposi tion, applied via NH4SO4 fertilizer, with three applications per year. Three years of pretreatment data were collected and used for calibrat ion. Stream water chemistry data collected during 3 years of treatment were evaluated. Stream water pH and electrical conductivity were not significantly affected by the elevated N and S inputs on either treatm ent watershed. On WS9, there were no statistically significant treatme nt effects on stream water export of Ca, SO4, or NO3. On WS3, however, stream export of both NO3 and Ca have increased as a result of acidif ication treatments. The implications of these results are discussed. R esearch is continuing so that the processes involved may be elucidated . In addition, effects on vegetation, aquatic invertebrates and amphib ians also are being evaluated.