Wetland
Management Wetland
ManagementWetlands mean different things to different individuals. Some people envision a dark, dreary swamp; others find a place to enjoy an early morning duck hunt or an afternoon of wildlife watching.
By definition, a wetland is a tract of land containing much soil moisture that supports certain types of water-tolerant vegetation. Lands that fit this description can vary from permanently flooded sloughs to areas that have only saturated soil during part of the year.
Wetlands function as biological filters that remove sediments and pollutants from surface waters. They also act as natural sponges, reducing flood severity by slowly discharging excess water back into the stream or groundwater table.
Wetlands are biologically rich, with a greater diversity of plants and animals than is found in drier habitats. They are excellent habitat for all kinds of waterfowl, shorebirds and songbirds. Natural wetlands along streams and rivers are important as fish spawning and rearing areas.
Historically, natural wetlands dominated the floodplains and river deltas in Missouri. During the past few decades, many were converted to agricultural land, and their benefits lost. As we look toward the future, we realize how important it is to preserve our few remaining natural wetlands and to develop new wetlands wherever possible.
Many of the wetlands in Missouri today are "developed" - that is, they were constructed on previously dry or seasonally flooded land and are maintained by levees and water-control devices. For information on construction and development of private wetlands, see Developing Wetlands.
Most wetland management today is directed toward creating good waterfowl habitat. In this type of management, production of food for waterfowl is a primary concern.
Diverse groups of plants grow naturally on moist or wet soil. These plants produce seeds that contain essential nutrients for waterfowl. They also provide excellent growing conditions for invertebrates, such as small snails, clams and insects, which are good waterfowl foods. Wetland management techniques encourage the growth of these moist-soil plants. In many cases, domestic grains are planted and then flooded for supplemental food.
Following are some procedures that produce many kinds of waterfowl foods, both natural and cultivated, under a variety of wetland conditions.
On developed wetlands, moist-soil plants are encouraged in flooded fields by drawing the water from the fields during the growing season. This allows germination of the seeds that are naturally present. The timing and rate of the drawdown are important for good plant growth. Although there is no set method for determining the best time to draw down a wetland, a general recommendation is that the water be held on the wetland until early summer (May through June). The drawdown is then begun by opening the water control structure. The rate of the drawdown should be slow enough to prevent rapid drying of the soil. This will discourage undesirable species while stimulating desirable moist-soil plants. The wetland is then reflooded to make these foods available for waterfowl. A slow, progressive reflooding of the marsh is best, starting around the first of September for teal or the first of October for many other wetland species.
Flooded grain crops can be very beneficial for waterfowl, especially late in
the winter when the weather is extremely cold. Corn or grain sorghum should
be flooded from Oct. 15 to March 30. Crops planted specifically for waterfowl
need not be clean-tilled because the weeds will provide additional food. Japanese
millet also can be sown (15 pounds per acre) to supplement the cultivated crops.
Bottomland forests are an important wetland habitat type. The management plan for a bottomland forest should protect the health of the trees; therefore, no flooding should occur during the growing season. Flooding dates, depths and duration should vary from year to year to maintain the productivity of the forest. In Missouri, a forested wetland usually can be flooded from Oct. 15 to Feb. 15. The water should be drained before the trees leaf out. A slow drawdown is better than a rapid one because more preferred plants will be produced. Open areas in the forest can be planted in Japanese millet or managed for natural foods.
Temporary or ephemeral pools are important breeding sites for various frogs and salamanders. These pools also are used by reptiles, migrating shorebirds, waterfowl and insects - all of which are important to the local ecosystem. Many temporary wetlands have become permanent pools of water that people have stocked with fish. This destroys their usefulness for frogs and salamanders because fish prey upon the eggs and the young of amphibians. It's no coincidence that most of the rare amphibians in Missouri use temporary pools for breeding.
While most of Missouri's amphibians are spring breeders, there are a few salamanders that breed in the fall. Some of the common species that use these areas are western chorus frogs, spring peepers, southern leopard frogs and tiger salamanders. In prairie areas, the northern crawfish frog and the Great Plains narrowmouth toad will use these pools.
To select a site for your pool, you should look for natural low spots or dips in the landscape that may hold water for short periods of time, particularly during the spring. These sites can occur almost anywhere - on flood plains, uplands, forests, fields or pastures. These areas may already have wetland plants, such as smartweed and sedges. If the site holds water for two or three months, there is a good chance it is already being used and shouldn't be disturbed. Areas on flood plains are especially attractive because they fill up during floods.
A small pool can be constructed in less than a day using a small bulldozer or a tractor and blade. A depth of 1-2 feet is ideal, and the pool should have sloping sides. Pools can be of almost any size or shape, depending on the site. Trees around the site should be left in place.
Once the pool is constructed, there is usually no need to introduce aquatic plants or animals. The soil in a seasonally wet area will frequently have a seed bank of wetland plants, and animals are good at finding wetlands on their own. If plants are introduced, care should be taken not to use aggressive species, such as cattails or purple loosestrife. If done correctly, your pool will dry up during the hottest part of the summer and fill up again in the fall or spring, just in time for the next breeding season.
If draining the pond or lake is possible, it should be drawn down 1-2 feet in early June to encourage beneficial plants, then allowed to refill with rainfall and runoff. Mudflats around ponds can be seeded to Japanese millet.
If water control is possible, sloughs can be managed as described above. If not, the following techniques can be used where feasible:
Wetland Management Tips:
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