Bog ecosystem characteristics and ecological processes

Bogs are unique ecosystems, at once wholly infertile and teeming with life. Our trip to the Orono Bog revealed that bogs are more than mud pits. They can be stunningly beautiful with a surprising array of wildlife, especially bird life. We saw several small songbirds along the boardwalk at Orono. Also called peatlands, bogs give rise to cranberries and similar small berries. Fungi, mosses, and flowers, including some bog-specific orchids, can all be sustained by bogs.

Although a bog is a type of wetland ecosystem, it differs significantly from marshes and swamps. Bogs are characterized by their "acidic and infertile" soil ("Bog FAQs"). Yet the term infertile belies the subtle life teeming within the bog. For instance, we could see and hear many insects, which provide nourishment not only for birds passing by but also for carnivorous plants like the pitcher plant. Bogs cannot sustain the type of flora and fauna that a forest will, though. Because of the acidic nature of the soil, the bog is devoid of trees and grasses. Their roots also cannot penetrate the thick mineral layer (class notes p. 2). However, a mat of moss known as sphagnum may provide a carpet upon which some plants and even trees like the tamarack can take root and grow (EPA). Thus, a bog is a heterogeneous ecosystem with many different manifestations, sections, and layers.

The Orono Bog is a raised bog, complete with moat, rand, and fen. Peat accumulation is higher in the center of the bog than at the edges, creating the domed terrain and also the moat surrounding it. The moat is created and sustained as rain waters flow down the rand, the sloping sides. Beyond the moat, we can see the gradual reintroduction of familiar vegetation such as woody trees and shrubs that cannot exist within the peaty part of the bog. I imagine that many of the passerine birds we witnessed along the boardwalk made their homes in the distant areas beyond the moat, and come to the bog for feeding time.

One of the most fascinating features of the Orono and other bogs is the way they are formed over the course of thousands of years. As with many bogs, the Orono was initially created by a melted glacier. The sea encroached upon the glacial waters, creating a "layer of silt and clay" at the bottom ("Bog FAQs"). Gradually the climate grew wetter and wetter, and the area became waterlogged ("Bog FAQs"). The flood plain enabled the growth of wetland plants. When those plants died, their remains would become compressed in the water, which when built up turned into peat. Peat is basically comprised of undecomposed plants. The thicker the peat, the slower the rate of decomposition for the plants within it. Peat is too thick for air or oxygen to penetrate, slowing decomposition and preventing the growth of new vegetation. According to the Orono Bog Web site, "thousands of generations of wetland plants have added their remains to a deepening layer of peat -- now as deep as 25 feet in some parts of the bog," ("Bog FAQs"). Thus, the Orono bog is growing before our eyes.