Productivity of temperate forests typically is limited by nitrogen supply Nitrogen cycling in forests is linked to regional and global environmental issues, such as groundwater quality and the trace gases composition of the atmosphere. Forests are being fertilized to stimulate forest growth to meet increasing demands for forest products, and are being used as "living filters" to remove nitrogen from applied wastewater. Extensive forested areas are receiving excessive additions of nitrogen through nitrogenous components of acid rain. Although general patterns of nitrogen cycling in unimpacted forests are known, little is known about the nitrogen accumulation potential of forests, or the ability of forests to handle chronic excess nitrogen additions. This research is first of all a comparative ecosystem study of the effects of excess nitrogen additions on nitrogen cycling in early, mid- and late-successional forests on Cape Cod, Massachusetts. Secondly, this study will take advantage of a natural experiment inadvertently set up by the Town of Falmouth, in which 24 hectares of forests and successional vegetation are scheduled to be irrigated with wastewater highly enriched with 15N, a stable isotope of nitrogen. The presence of this 15N label will enable isotopic analyses to be used to trace the fate of the wastewater nitrogen added to the Cape Code forests. The research at the Falmouth site began in 1985, when the wastewater treatment plant was still under construction. In the elapsed 2.5 years a baseline study of nitrogen cycling in the forests has been completed. It is expected that research results will be of fundamental ecological importance and applicable to the treatment and use of municipal wastes.
