Stream water and soil solution responses to 5 years of nitrogen and sulfur additions at the Frenow Experimental Forest, West Virginia

To examine the effects of elevated N and S inputs on a central hardwood forest, a whole-watershed acidification experiment was initiated in 1989 on the Fernow Experimental Forest, West Virginia. Annual experimental additions of 40 kg S ha(-1) year(-1) and 35 kg N ha(-1) year(-1) as ammonium sulfate fertilizer were applied to a 34 ha watershed with a 25-year-old stand of central Appalachian hardwoods. An adjacent watershed served as the control. After 5 years of treatment (total additions of 275 kg S ha(-1) and 220 kg N ha(-1)), stream water NO3-, Ca2+, Mg2+ concentrations and export increased. Soil solution concentrations provide evidence that the treatment watershed is nitro en saturated, which was unexpected for such a young stand. No statistically significant changes in annual SO42- export were observed, but peak stream water concentrations of SO42- did increase during the treatment period. Changes in soil solution chemistry suggest that the treated watershed also may be approaching SO42- saturation. (C) 1997 Published by Elsevier Science B.V.