Tuesday, November 14, 2006

Linkages Between Fine Root Dynamics and Soil Chemistry at Three Long-Term Nitrogen Manipulation Experiments in the Northeastern United States.

Lindsey Rustad, USDA Forest Service, 35 Crystal Ln., Cumberland, ME 04021-9538, Ivan Fernandez, Univ of Maine, 5722 Deering Hall, Room 1, Orono, ME 04469-5722, Steve Mcnulty, USDA Forest Service, 920 Main Campus Dr, Suite 300, Raleigh, NC 27606, and Allison Magill, Univ of New Hampshire, Complex Research Center, Durham, NH 03824.

Concerns exist that chronically elevated atmospheric N deposition may have negative effects on forest health.  Although considerable research has focused on the response of aboveground ecosystems to this non-point source pollutant, less is known about the response of the belowground ecosystem.  We  therefore initiated a study to evaluate the response of fine root and soil chemistry  to experimental N additions at three long-term (>15 yrs) study sites in the northeastern US (the Bear Brook Watershed in ME, the Harvard Forest in MA, and Mt. Ascutney in VT).  Data for the O horizon for  the 2002 field season showed  that, in general, O horizon fine root and soil N concentrations either increased or showed no change, O horizon fine root and soil base cation (Ca and Mg) concentrations either declined or showed no change, and O horizon fine root and soil P concentrations showed a variable response with increased root and soil P concentrations at the BBWM hardwood site, and either decreased or no change in root and soil P concentrations at the other sites.  Linkages between root and soil chemistry will be discussed.