PARENT SESSION
Oral Session #33: Climate Change. Presiding: A. Peterson.
Tuesday, August 7, 2001. 1:00 PM to 5:00 PM. Hall of Ideas E.
Changes in foliar biochemical stress indicators (putrescine and arginine) and their relationship to foliar and soil chemistry in response to acid deposition in Delaware River Basin.
Minocha, Rakesh1, Shortle, Walter1, Lawrence, Gregory2, Ross, Don3, Hallett, Richard1, Long, Stephanie1, 1 2 3
ABSTRACT- The Catskill Mountains of New York are located in the upper Delaware River Basin. This heavily forested area is an important source of drinking water, timber, wildlife and recreation and has long received high inputs of acid deposition that have the potential of depleting reserves of calcium in soils needed for proper root development and function of plants and for productive streams. These effects may not result in any visible injury to the plants, but may cause subtle, yet detectable physiological and biochemical alterations. Foliar samples from sugar maple and yellow birch as well as soil samples in their vicinity were collected from the Neversink River Valley from 4 plots (ridge top, upper, mid, and lower slope). The concentrations of putrescine and arginine (a possible specific indicator of excess nitrogen), were highest at the ridge top and lowest at the lower slope indicating high physiological stress at ridge top. This observation was accompanied by highest concentrations of foliar N and soil ammonia, nitrate, and monomeric Al but lowest concentrations of foliar and soil solution Ca and Mg at the ridge top. At this plot, the initial nitrate concentration was six times higher and the nitrification rate three times higher than the average of sixteen sites across the northeastern USA. These data suggest that trees at the ridge top are under stress that is originating from high nitrogen input at this site.
KEY WORDS: biochemical stress indicators, calcium and magnesium depletion, acid deposition, nitrification