May 19, 1999 Over the past 20 years, two University of Maine scientists have crisscrossed thousands of acres of Maine’s soggiest, most inhospitable terrain in a project which will have long-term conservation benefits.
Ronald Davis of Orono, Dennis Anderson of Stetson and Davis’ students have walked, driven and flown from the rolling hills of southern York County to the western mountains, the Down East coast and industrial forests of northern Aroostook.
Their mission is to systematically paint a detailed picture of the state’s organic wetlands, also known as peatlands, one of Maine’s most poorly understood natural resources.
Last December, the Maine Agricultural and Forest Experiment Station published some of the researchers’ comprehensive data for 108 peatlands in "The Flora and Plant Communities of Maine Peatlands." Another report is planned on the nearly 1,100 peatlands which Davis and Anderson have surveyed on the ground, on air photos and from the air.
By compiling information about peatlands from one end of Maine to the other, Davis and Anderson have created a foundation for ongoing efforts by the State and non-profit organizations to conserve peatlands as part of Maine’s natural heritage.
Indicators of climate change
Their latest studies are focusing on the factors that affect plant growth in peatlands, how these areas are affected by climate and what sorts of changes may be expected if regional temperatures and precipitation patterns shift. Because of their dependence on temperature patterns and water levels, peatlands are sensitive indicators of climate, says Davis. That work is currently proceeding in Caribou Bog just west of Orono and Old Town.
Peatlands are saturated wetlands in which peat accumulates slowly, year after year. In Maine, these growing mounds of partially decayed plants range in depths from a foot or less to as much as 30 feet. They are inhabited by unusual plant communities including species such as mosses, pitcher plants and black spruce trees that have been stunted in their growth.
"We use a large database to develop the standards about what is rare, what is common and where peatlands are distributed," says Davis. "We also score peatlands using other criteria such as diversity, the numbers of plant species and hydrologic features."
"The scores are used for a ranking, which is a conservation evaluation. It amounts to a recommendation about what peatlands should be protected from development, which ones are exemplary or unique on the basis of these features, as opposed to those which seem to be more run of the mill. Although I don’t think we want any of our wetlands to be disturbed, this system gives some guidelines."
Just as important scientifically, this extensive wetlands survey has generated new information for research. "Before we started this, the distribution of peatland types in Maine was very poorly known," says Davis. "The vegetation, the plants, the floristic composition, the distribution of the flora are now much better documented.
"One of our major conclusions is that scientific classification systems of peatlands based on vegetation don’t work very well. This is well known in northern Europe. Large peatlands are complexes. One peatland may contain as many as 17 vegetation types. In Maine, we have also discovered types of peatlands that have large continental distributions in Eurasia and Canada but that were unknown here."
Two undergraduate students, Brian Frappier from Manville, Rhode Island and Sara Bercume from Windham, Maine are currently completing research with Davis and Anderson to understand why some plants, such as black spruce, grow rapidly in some parts of a peatland and slowly in others. They are also interested in the relative ages of peatlands. Although some areas of peat may be deeper than others, says Davis, they all may have accumulated over the same period of time. Differences in depth, he explains, are the result of variations in how quickly old leaves and stems decay in a particular location.
Monitoring water levels, chemistry
In the south unit of Caribou Bog, Davis, Anderson and Andrew Reeve of the UMaine Department of Geological Sciences have established eight monitoring stations. Each one consists of hydrologic monitoring wells that have been sunk to varying depths in the peat and plots for tracking various vegetation characteristics.
The scientists keep track of water levels and collect water samples on a regular basis. The samples are analyzed for chemical characteristics such as plant nutrients and acidity. They also plan to conduct experiments to determine how changes in water flow or nutrient concentrations affect the decay process.
This spring and summer, the research team is establishing ten more stations in the central unit of the Bog. Eventually, they intend to have a network which reflects the full range of depths of peat and a wide range of hydrologic conditions.
The researchers chose Caribou Bog because it is representative of Maine’s peatlands and is conveniently close to Orono. "Caribou Bog is a good middle ground because it typifies a large area Maine in terms of plant diversity. It is twelve miles long from north to south. You can see a tiny portion of it from I-95. It extends from Bangor and Veazie all the way up to Hudson and Alton," says Davis.
Underlying the bog, says Davis, are layers of lake sediments and marine clay. The clay was left by sea water which flowed into central Maine after the end of the last ice age. It appears, he adds, that the center of the bog filled with freshwater when the sea retreated to the present day coastline about 12,000 years ago.
Davis has taught courses in ecological subjects at UMaine since the 1970s and wetland courses since the 1980s. He has also specialized in the study of environmental history and acid rain through the study of lake sediments. His studies of lakes and wetlands have taken him to other parts of New England as well as the Caribbean and Asia. His research has been supported by the Agricultural and Forest Experiment Station, the U.S. Geological Survey and the National Science Foundation.
Anderson came to UMaine in 1977 to work with Davis as a research assistant and presently holds the rank of associate scientist. He specializes in plant ecology and has emphasized the statistical analysis of large ecological data sets. He worked briefly for the U.S. Forest Service in Oregon before settling in Maine.
"Our relationship has been really productive," says Davis. "As the years have gone along, Dennis has taken up more and more of an independent role as a researcher."
"Dennis’ statistical expertise has been very useful not only to our program but to at least 15 graduate students and numerous faculty in the department over the years. He’s been a very valuable resource for the department."
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