A Watershed
Landmark experimental acidification project informs our understanding of forest soil and water quality in the North Woods
by Jessica BlochMore than a quarter-century ago, University of Maine geochemist Stephen Norton, forest soils scientist Ivan Fernandez and colleagues wrote a U.S. Environmental Protection Agency grant proposal that launched a landmark whole-watershed manipulation project to study effects of acid precipitation. Norton, a national expert on acid rain, and his research team identified the perfect spot in the North Woods — a paired-stream watershed on the southeast slope of Lead Mountain in northern Hancock County, known as Bear Brook.
Literally and figuratively, it was a watershed moment in the study of long-term experimental acidification. Today, the Bear Brook Watershed in Maine (BBWM) research program is internationally recognized for its contributions to our understanding of the effects of elevated atmospheric nitrogen and sulfur deposition in forests.
Research began on the privately owned land in 1987 and has continued since, making Bear Brook one of the longest experiments of its kind in the world and the oldest in the U.S., along with a partner site in West Virginia. And while the initial research was part of the national agenda to determine the effects of acid rain, the scope of BBWM has evolved to address some of the most pressing issues of our day related to forest soil and water quality, including climate change, carbon sequestration, nitrogen saturation, acidification, and depletion of calcium and other nutrients from forest soils.
Through the years, grants from the EPA, the National Science Foundation and other sources have brought more than $11 million in funding to UMaine for work at Bear Brook, and provided support for dozens of undergraduates to experience lab and fieldwork, and graduate students to pursue high-level research. The experiment includes bimonthly applications via helicopter of an ammonium sulfate fertilizer to the West Bear watershed, simulating elevated levels of nitrogen and sulfur on forested watersheds. The adjacent East Bear watershed remains untreated to serve as a reference, and to study the recovery of watershed systems in response to improvements in air quality as a result of the Clean Air Act. Through the years, continuous high-frequency stream monitoring has been done collaboratively with the U.S. Geological Survey.
Because of its long-term nature, the Bear Brook study has allowed UMaine researchers to see ecological responses that would likely not have been identified in a typical three- to five-year study.
Image Description: Water Fall
Summer 2012
