Have you ever gone fishing or canoeing, listened for frogs, searched for spotted salamanders, or been entranced by a stand of Cahaba Lilies? Then chances are you have set foot in a wetland.

Wetlands provide ample opportunities to experience a diversity of plant and animal life in habitats that are unique among wet landscapes. In fact, Alabama ranks fifth in the nation in number or diversity of plant and animal species found throughout the United States, largely due to the biodiversity provided by wetlands.

Simply put, a wetland is an area of land between terrestrial and aquatic environments, often considered a transitional zone encompassing aspects of both terrains. (Follow the link to a diagram that clearly depicts how wetlands act as transitional habitatss - Canada's Aquatic Environments.)

According to the Environmental Protection Agency (EPA), “Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including…the growing season. Water saturation largely determines how the soil develops and the types of plant and animal communities living in and on the soil. Wetlands may support both aquatic and terrestrial species. The prolonged presence of water creates conditions that favor the growth of specially adapted plants and promotes the development of characteristic wetland soils.” -- EPA, America's Wetlands: Our Vital Link Between Land and Water

The “Three H’s”
Three major criteria are used to classify the presence of a wetland:
Hydrology
Hydric Soils
Hydrophytic Plants

*Hydrology (presence, abundance, and source of water)—the amount and persistence of water present in a wetland is the most important characteristic, for this is what determines the structure and function of a particular wetland. The presence of water creates conditions that are favorable for the remaining two components of wetlands - hydric soils and hydrophytic vegetation. Depending on the type of wetland, some are permanently saturated with water, while others tend to have fluctuating water levels throughout the year.

*Hydric Soils (waterlogged soils)—these soils contain so much water that there is no room for oxygen, creating anaerobic conditions. Gone is the normal reddish or yellowish tint to the soil, instead replaced by large patches of gray or orange-colored spots, which is a result of the accumulation of decomposing organic matter. The lack of oxygen in the soil determines what type of plants will be present.

*Hydrophytic Vegetation (“water-loving” vegetation)—these types of plants are the most obvious indicator of a wetland because they are adapted to wet environments and can grow under anaerobic conditions. Wetland plants may employ any number of strategies in order to survive; including adventitious roots (roots that grow out of the stem above ground), surface roots (those growing along or just above the soil surface), or lenticels (small pores on the outer skin that allow for gas exchange).

See next: Importance of Wetlands