Effects of chronic nitrogen additions on understory species in a red pine plantation
1999
Rainey, Susan M. | Nadelhoffer, Knute J. | Silver, Whendee L. | Downs, Martha R.
Two plots in a red pine stand at the Harvard Forest, Massachusetts, have been fertilized for 7 yr with 5 g·m⁻²·yr⁻¹ or 15 g·m⁻²·yr⁻¹ of N and compared to an unfertilized control to study the effects of chronic N additions on nutrient cycling, plants, and soil. Movement of added N into soils and plant biomass was tracked using additions of an ¹⁵N label to the 5 g·m⁻²·yr⁻¹ and control plots for two of these years. We present data on changes in the understory plant community of these plots. We measured aboveground biomass, density, N and other elemental concentrations, and ¹⁵N tracer recoveries to catalogue the effects of the N additions on this community. Nitrogen contents increased while biomass and nutrient cation concentrations decreased in some species. Percent recoveries of ¹⁵N tracers were small but detectable. The natural abundances of ¹⁵N also increased in a fertilized treatment without tracer additions. Though this forest has not yet reached N saturation by some definitions, it is possible that the understory is already saturated with N. Understory species may be useful indicators for N saturation through their increasing N content, decreasing nutrient concentrations, and increasing δ¹⁵N in tissues.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library