Nutrient-poor and acidic, a bog is a peat-accumulating wetland comprised of acidophilic vegetation, particularly Sphagnum mosses species and ericad shrubs. Although bogs are water-saturated, they have virtually no inflow or outflow of mineral-bearing water. Isolated from the groundwater table, their only source of nutrients is precipitation. Most bogs in Massachusetts, Connecticut, and Rhode Island are level bogs, also called flat or basin bogs. They have their origins at stream headwaters, in isolated valley bottoms or depressions, around pond or lake margins, or in kettlehole ponds formed by receding glaciers more than 10,000 years ago. Most of the bogs in southern New England have some degree of surface water or groundwater input, so they are technically classified as poor or acidic fens; in Maine, these peatlands are called unpatterned fen ecosystems.
True bogs include raised bogs, with peat domes high above the basin surface, and blanket bogs, where peat covers hundreds of acres of terrain, and are found in Maine, the Great Lakes Region, and Canada where cool and moist conditions generate deposition and accumulation of thicker layers of peat. In the peatlands of southern New England, peat accumulates but does not expand beyond the physical limits of the basin or depression. Also, the bog surface usually is level or only slightly elevated. Level bogs are not restricted to southern New England; they are common throughout the glaciated regions of the United States.
Although most of the level bogs and acidic fens of southern New England are not true bogs hydrologically, their plant communities are characteristic of peatland vegetation. An individual peatland usually contains several natural plant communities.
In kettlehole bogs, the plant communities often form concentric rings around the pond; in pond border bogs, the ringed zonation is less distinct or is absent. Vegetation patterns change from pond edge to upland edge based on environmental gradients of hydrology, topography, water chemistry, abundance of nutrients, and depth of the peat mat. Due to fluctuating water levels and nutrient regime, size and species composition of the plant communities can vary from peatland to peatland.
The caveat here is: not only does vegetation vary floristically from one peatland to another, it also varies within an individual peatland, as a bog is usually home to more than one type of plant community. As often as not, the plant assemblages grade into transition zones that may be barely distinguishable out in the bog. In some bogs, one or more community types may be absent. Bogs and acidic fens are fascinating not only because they are wet and soggy, because each one is truly unique.
To explore the plants found in the acidic peatlands of Southern New England, click on the species list, the species list with photos, or search for your favorite bog plant.