LTREB: Biogeochemical Mechanisms of Response in the Third Decade of Whole-Ecosystem Experimental Manipulations at the Bear Brook Watershed in Maine (BBWM)

This grant will support the Bear Brook Watershed in Maine (BBWM) where research has been conducted for approximately 20 years on the effects of atmospheric sulfur and nitrogen deposition on forests. The research is conducted on two watersheds, each drained by a first order stream. One is treated bimonthly by helicopter to simulate atmospheric deposition of sulfur and nitrogen. Over the past 20 years, this research has identified and verified key factors governing forest response to air pollution, and also revealed major gaps in our understanding that are critical to determining the success of current and potential future regulations under the Clean Air Act and its amendments of 1990. Recent research is also studying how climate interacts with other air pollutants to determine water quality and forest health. This grant will support the project into the third decade where new ecological response mechanisms are emerging that can only be investigated by long-term, multi-decadal research.The broader impacts of this project include the training of undergraduate and graduate students who will be the scientific leaders of tomorrow. This research provides direct evidence of whole-ecosystem responses to chemical treatments that simulate air pollutants providing results not possible from controlled laboratory studies. The issue of acid deposition remains a concern for forest ecosystem health and water quality. There are also direct interactions between climate and acid deposition that few field research sites in the world are prepared to study. This research directly addresses those information needs for today and the future