Wetlands

The wetlands that are all around us, have many unique environmental benefits, including some of the highest diversity of plant species, compared to other ecological communities. Likewise, there are a number of animals that count very heavily on wetlands for habitat, especially rare species like North American crocodiles, red wolves, and swallow tail kites. These soggy areas also soak up and hold water, which helps to prevent flooding, filter out nutrients, and prevent erosion and sedimentation.

Just what is a wetland? There are many definitions, but one of the most comprehensive is the definition of a Jurisdictional Wetland that the Environmental Protection Agency (EPA) employs. According to the EPA, a wetland needs to have water present throughout the growing season (necessary hydrology). There must be plants that can withstand wet conditions (hydrophytes), and finally, the wetland needs to have hydric soils. (Hydric soils are often recognized by black or gray coloring in the subsoil, indicative of anaerobic conditions [lack of oxygen].) There are four main types of wetlands: marshes, swamps, bogs, and fens.

A marsh is a wetland that is frequently or continually inundated with water, hosting mostly soft-stemmed vegetation like reeds, pickerel grass, cattails, wild rice, water lilies, and bulrush. Marshes are tidal or nontidal, depending on whether or not they are affected by the tides, existing in the low points of the landscape, often adjacent to a lake, river, or saltwater. These areas obtain most of their water through runoff, and they trap much of the nutrients associated with this runoff. As a result, marshes are very fertile and productive, providing very important buffers around water bodies as well as the shoreline, from preventing erosion. The Everglades are an example of a tidal marsh.

A swamp is a wetland dominated by woody plants. They can be part of a forest, or they can contain scattered trees and shrubs. Swamps generally contain surface water throughout the growing season, and contain a lot of organic matter in the soil. Associated with wide flood plains, swamps are normally found around slow moving streams. Some of the woody plants associated with swamps include willow, cypress, Atlantic white cedar, silver maple, and water tupelo. Shrubs common to swampy areas include buttonbush, alder, and chokeberry. Some examples of swamps include the Great Dismal Swamp of Virginia and the mangrove swamps of Florida.

Bogs are usually formed when lakes gradually fill with a thick, spongy mat of sphagnum moss. The development of bogs occurs primarily in the north, when glaciated lakes that formed in broad flat upland areas are gradually colonized by sphagnum. Most bogs are found in the Great Lakes region, Canada, and the Northeast; however, bogs are present in Western Maryland, as well. These communities are normally fed by rainwater, and they develop highly acidic conditions, a somewhat harsh infertile environment, that favors acid-loving plants or carnivorous plants. Some of these, like pitcher plants or sundews, trap and digest insects and smaller animals to obtain their nutrients. Other plants that thrive in bogs include cranberries, tamarack, black spruce, and northern white cedar. While most bogs are found in the north, there is a boggy area known as a “pocosins” that is associated with the southern part of the Atlantic Coastal Plane, extending from Virginia down to Florida, most of them found in the Carolinas. Pocosins are normally dominated by evergreen trees and shrubs such as red bay, sweet bay, loblolly pine, and pond pine. These are dense, inhospitable areas; there is a large pocosin in North Carolina that is home to one of the remaining wild populations of the red wolf.

Fens are formed when peat begins to overtake a pond area, but because these areas are fed with a moving water source, like a stream or spring, they never develop high acidity, and they are much more fertile than a bog. Fens, like bogs, are normally found in the northern hemisphere, containing much more species diversity than a bog, hosting plants such as grasses, reeds, sedges, rushes, wildflowers, and poison sumac. Fens are normally very wet, with trees found growing at the outer edges. Some trees that are commonly associated with fens include Atlantic white cedar, northern white cedar, paper birch, and tamarack.

Article by Mike Kay, Frederick County Forestry Board

Page header photo credit: wikimedia.org

Nature note for 3/22/22