The 616-acre Orono Bog in Orono, Maine, comprises a fascinating peat-based environment where nutrients are scarce and even ancient pines grow to less than five feet tall. Allowing visitors to experience and learn about the bog without disturbing the fragile ecosystem is a 4,200-foot boardwalk that winds through the changing habitats of the complex.
The nearly mile-long boardwalk itself was initiated in 2000 by the University of Maine to allow students and the public to observe the bog without damaging its fragile plants. Construction began in 2002 and was completed in spring 2003.
The boardwalk starts near the bog edge, in what can be considered a typical Northeast mixed forest of pines and hardwoods. From there it enters the bog’s edge habitat of red maple, tamarack, white cedar, ferns, and other plants that thrive in the water-soaked perimeter of the bog. As the boardwalk enters the heart of the bog, the vegetation thins and becomes more stunted, evidence of the bog’s dearth of nutrients. Seven informational stations can be found along the nearly mile-long boardwalk, describing each part of the bog complex and the different plants and animals that inhabit them.
The Orono Bog began some 10,000 years ago, after the glaciers that covered much of Maine retreated and ocean waters crept inland. As the land, which had been compressed by the massive weight of the glaciers, gradually rebounded and the ocean receded, it formed lakes and ponds. The Orono Bog was once such a lake. As the lakebed dried, it allowed sphagnum moss to thrive. The spongy moss formed the basis of the bog’s underlying peat substrate, which in some parts of the bog is 25 feet deep.
Peat is composed of partially decomposed organic matter and typically a lot of water. Unlike upland forests, the saturated peatland system is largely starved of dissolved oxygen below the surface, inhibiting the rate of decay. As the rate of plant-matter accumulation exceeds the rate of decomposition, thick layers of peat are established over time. The accumulation of peat also impedes the movement of dissolved oxygen in the peat water, creating a self-perpetuating cycle that supports the buildup of more and more peat.
Like many peat bogs, the center of the Orono Bog complex is higher than its edges. This dome-like topography causes water to drain toward the perimeter, forming a moat-like zone called a lagg. In the Orono Bog, the lagg drains the entire bog complex toward Pushaw Lake to the northwest.
Nutrient-rich upland soils from the forest surrounding the bog drain into the swampy lagg, where they support large trees like red maple and understory plants. However, these nutrients never reach the center of the bog. Because of the bog’s raised topography, delivery of nutrients is limited to atmospheric events, such as rain, fog, mist, snow, and particles carried by the wind. This is why the trees and shrubs in the central part of the bog remain stunted, despite being as old, or older, than trees only a half-mile distant in the surrounding forest.
However, other plants in the Orono Bog have adapted to their nutrient-starved environment through carnivory. Carnivorous plants obtain additional nutrients by trapping and digesting small animals. The four species of carnivorous plants in the Orono Bog include pitcher plant, roundleaf sundew, spoonleaf sundew, and horned bladderwort. These specialized plants supplement their nutrient intake by trapping and digesting insects, spiders, mites, and micro-organisms.
The Orono Bog complex also hosts a wide variety of birds throughout the year. Depending on the season, visitors may encounter warblers, raptors, sparrows, and more. This makes the bog an ideal spot for birding.
The Orono Boardwalk is open from May to late November. Hours are 7:00 a.m. to 6:30 p.m. The boardwalk is accessible to wheelchairs. Dogs and bicycles are not allowed on the boardwalk. Visit the Orono Bog Boardwalk’s website for details.
An all-encompassing guide to the Orono Bog can be purchased through the University of Maine Press for $28.
