Research at the Bear Brook Watershed in Maine has been conducted for more than 25 years on the effects of atmospheric sulfur and nitrogen deposition on forest, soils, and stream runoff, in a changing climate. Each watershed includes a headwater stream. One watershed is treated bimonthly by helicopter (simulating atmospheric sulfur and nitrogen deposition) and the other is an untreated reference. This project will support the third decade of research, which explores new ecological response mechanisms 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. This research also provides direct evidence of whole-ecosystem responses to chemical treatments that simulate air pollutants, providing results not possible from controlled laboratory studies. This research has identified and verified key factors governing forest response to sulfur and nitrogen deposition, and revealed major gaps in our understanding that are critical to determining the success of current and future influences of the Clean Air Act. Societal concerns about the effects of acid deposition, reactive nitrogen, and climate change on forest ecosystem services grow increasingly important. This research directly addresses those information needs for today and the future.