Chapter 15 Wetlands 373 Copyright Goodheart-Willcox Co., Inc. They provide resting areas and have an abundance of different berries and other soft mast. Pocosins also protect water quality of estuaries, help control fl ooding, prevent erosion, and perform as carbon sinks. According to the EPA, pocosins are one of the most endangered wetland types. Pocosins were once very prominent but many have been cleared for silvi- culture (forestry), land development, and crop cultivation. These wetland areas do not possess the soil qualities needed for agricultural purposes and farmers must add substantial fertilizers once the land is dredged and drained to increase growing potential. Clearing pocosins also changes the landscape which affects water fl ow to surrounding areas and increases potential for fl ooding. Prairie Potholes A prairie pothole is a hole or depression in low-lying areas where water collects and pools, Figure 15-20. While many of these depressions are short lived, others are permanent wetlands. Permanent prairie potholes have fl oating and aquatic plants growing in the center or deeper water, and marsh grasses and cattails growing along the shoreline in the shallower areas. Prairie potholes were formed as glaciers retreated and are found primarily across several states in the Midwestern portion of the United States. These wetlands are extremely important to migratory birds as vital habitats for resting and feeding. Many of these wetlands have been elimi- nated to enable more agricultural production, and many of the remaining potholes are as endangered as some of the wildlife they support. Swamps Swamps are forested wetlands that rely on other freshwater sources, such as rivers or lakes, for their moisture. Although they are similar to marshes, their distinguishing feature is the predomi- nate presence of trees. Although the soil in swamps can be nutrient- rich mineral soil, few plant species other than water-loving trees tolerate the shade and anaerobic conditions. The types of plants and animals in a swamp are determined by the swamp’s climate, loca- tion, and topography (features of the land area), Figure 15-21. Swamps provide habitats for a wide variety of animal species. In Louisiana, for example, many species of reptiles, birds, amphibians, and fi sh live in the state’s estimated 20,000 square miles of wetlands. There is also an estimated one million alligators living across the state. The slow-moving stagnant waters also support many insect species. Depending on the swamp’s location and main water resource, the water may be freshwater, brackish, or saltwater. Some swamps also experience seasonal dry periods. vagabond54/Shutterstock.com Figure 15-20. Many prairie potholes were formed as glaciers retreated. These potholes may stay wet for a few days, weeks, or months depending on the depth of groundwater saturation. psv/Shutterstock.com Figure 15-21. Swamps rely on other water sources to maintain moisture levels. Swamps are vital groundwater filters and essential to reducing floods and floodwater damage.