Concerns exist that chronically elevated atmospheric N deposition may have negative effects on forest health and productivity. Although considerable research has focused on the response of the aboveground ecosystem to this non-point source pollutant, less is known about the response of the belowground ecosystem. We have conducted a three year study (2002-2004) to evaluate the response of fine root biomass, metabolism, chemistry, and turnover 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). Results have shown significant decreases in mean live fine root (< 1mm) biomass (-12 to -63%) and total soil respiration (- 20 to -31%), and increases in live fine root (< 1mm) nitrogen concentrations (+7 to +40%). Data will be reported here on the temporal and depth-related response of total fine root length growth and longevity to experimental nitrogen additions for the 2003 and 2004 field seasons. Results from this field study demonstrate that experimental N additions can significantly alter fine root growth and metabolism, which may have implications for forest susceptibility to additional stress factors, including drought and pathogens.