Decadal responses in soil N dynamics at the Bear Brook Watershed in Maine, USA

Abstract

Atmospheric nitrogen deposition to forested ecosystems is a concern because of both geochemical and biological consequences for ecosystem integrity. High levels of prolonged N deposition can lead to "N saturation" of the ecosystem. The Bear Brook Watershed in Maine is a long-term, paired forested watershed experiment with over a decade of experimental N additions (~34 kg ha^-1 per year = ambient + treatment) to investigate the biogeochemical consequences of N saturation. Both in situ and laboratory studies of N mineralization and nitrification were carried out to evaluate the changes in N cycling brought about by the long-term N additions. Consistent with hypotheses set forth in the literature (sensu [BioScience 39 (1989) 378]), the treated watershed had higher rates of N cycling compared to the reference watershed. In addition, we report important differences in N cycling rates as a function of forest cover type and soil horizon.

Citation

Jefts, Sultana; Fernandez, Ivan J.; Rustad, Lindwey E.; Dail, D. Bryan. 2004. Decadal responses in soil N dynamics at the Bear Brook Watershed in Maine, USA. Forest Ecology and Management. 189: 189-205.