SYMPTOMS OF NITROGEN SATURATION IN 2 CENTRAL APPALACHIAN HARDWOOD FOREST ECOSYSTEMS

By synthesizing more than twenty years of research at the Fernow Exper imental Forest, we have documented 7 symptoms of nitrogen saturation i n two adjacent watersheds. The symptoms include: 1) high relative rate s of net nitrification, 2) long-term increases in streamwater concentr ations of nitrate and base cations, 3) relatively high nitrate concent rations in solution losses, 4) little seasonal variability in stream-w ater nitrate concentrations, 5) a high discharge of nitrate from a you ng aggrading forest, 6) a rapid increase in nitrate loss following fer tilization of a young aggrading forest, and 7) low retention of inorga nic nitrogen when compared with other forested sites. These data suppo rt current conceptual models of nitrogen saturation and provide a stro ng, and perhaps the best, example of nitrogen saturation in the United States.