Changes in conifer and deciduous forest foliar and forest floor chemistry and basal area tree growth across a nitrogen (N) deposition gradient in the northeastern US.
We evaluated foliar and forest floor chemistry across a gradient of N deposition in the Northeast at 11 red spruce (Picea rubens Sarg.) sites in 1987/1988 and foliar and forest floor chemistry and basal area growth at six paired spruce and deciduous sites in 1999. The six red spruce plots were a subset of the original 1987/1988 spruce sites. In 1999, we observed a significant correlation between mean growing season temperature and red spruce basal area growth. Red spruce and deciduous foliar %N correlated significantly with N deposition. Although N deposition has not changed significantly from 1987/1988 to 1999, net nitrification potential decreased significantly at Whiteface. This decrease in net potential nitrification is not consistent with the N saturation hypothesis and suggests that non-N deposition controls, such as climatic factors and immobilization of down dead wood, might have limited N cycling.
Boggs
Johnny L
JL
Southern Global Change Program, Southern Research Station, USDA Forest Service, 920 Main Campus Drive, Suite 300, Venture Center II, Raleigh, NC 27606, USA. jboggs@ncsu.edu
McNulty
Steven G
SG
Pardo
Linda H
LH
D031002:Acer / Q000254:growth & development; D000393:Air Pollutants / Q000009:adverse effects*; D001061:Appalachian Region; D004784:Environmental Monitoring / Q000379:methods*; D009511:New England; D009584:Nitrogen / Q000009:adverse effects*; D028223:Pinus / Q000254:growth & development; D018515:Plant Leaves / Q000254:growth & development*; D013995:Time; D014197:Trees / Q000254:growth & development*
D000393:Air Pollutants; D009584:Nitrogen