Wetland Environments

 Wetland Environments

Your canoe slips quietly through the brown-tinged waters of the marsh in South Dakota's Lacreek National Wildlife Refuge. Paddling among the thick clumps of velvety golden cattails, you scan for bird's nests. A spot of red catches your eye, and you realize you are only centimeters away from a black-and-white grebe sitting still atop a nest of dry rushes. Suddenly, a loud honking sound breaks the silence, as a huge flock of Canada geese flies by. You gasp as some of the black and gray-brown birds land on a grassy mound nearby. Their out-spread wings must be almost as long as your canoe!

The waters of this marsh serve as an essential stopover for thousands of geese, swans, and other migrating birds. Birds stop to feed on grass and seeds as they fly south to their winter homes. Like other wetlands, the Lacreek marsh is a vital habitat for birds and many other living things.

What is a Wetland?

What image does the word wetland bring to mind? As the photographs on the next page show, not all wetlands are dark, smelly swamps oozing with mud. A wetland is an area of land that is covered with a shallow layer of water during some or all of the year. Wetlands form in places where water is trapped in low areas or where groundwater seeps onto the land's surface. They can range in size from a water-filled roadside ditch to an area covering thousands of square kilometers. Some wetlands fill up during spring rains and dry up over the summer. Others, like the Lacreek marsh, are covered with water year-round.

Marshes, swamps, and bogs are three common types of freshwater wetlands. Marshes generally are grassy areas covered by a shallow layer or stream of water. They contain cattails, rushes, tule, and other tall grass-like plants. Swamps look more like flooded forests, with trees and shrubs growing in the water. In the United States, many swamps are located in the south, where trees grow quickly in a warm, humid climate. The cypress swamps of Mississippi and Louisiana are examples of wooded swamps. Bogs, which are more common in cooler northern states, often form in depressions left by melting ice sheets thousands of mosses thrive in the conditions found in bogs.

Wetlands along coasts usually contain both fresh and salt water. Salt marshes are found along both coasts of the United States. They often contain tall, strong grasses growing in a rich, muddy bottom. Mangrove forests, found along the central and southern coasts of Florida, consist of short trees with a thick tangle of roots. The tough roots anchor the mangroves against tropical winds and storms.