Photo by Mike Budd.
Wetland Restoration Part 3: High Quality Wetlands Need High Quality Management
This is the final article in a 3-part series focusing on wetland restoration and management. Be sure to read Part 1: Building a Duck Hole which discusses the U.S. Fish and Wildlife Service Partners Program’s process of determining a site’s potential for wetland restoration and Part 2: Reading the Landscape which highlights the wetland design and construction process.
Part 3 provides a wetland manager with the information and tools to determine necessary management activities. Generally, management actions should promote long-term wetland functions and be directed by a landowner’s conservation goals and objectives. For many landowners, the conservation goal is to provide high quality food sources for waterfowl. To reach this goal, a manager may manipulate water levels to obtain optimal growing conditions for moist soil plants. Simply put, duck food is high quality moist soil plants. Moist soil plants grow in early successional habitat. Management and disturbance are required to maintain early successional habitat. Management = Disturbance = Duck Food.
Native Plants and Local Protein (aka “duck food”)
Wetland vegetation provides food and cover for waterfowl, songbirds, pollinators, amphibians, reptiles, fish and insects. Arrowhead (duck potato), beggar-ticks (stick tights), barnyard grass (wild millet), smartweed and duckweed are important and highly valuable native wetland plants. Beggar-ticks, for example, is a prolific seed producer whose seeds are regularly devoured by mallards. The seeds provide waterfowl an excellent source of protein, highly digestible carbohydrates, fat and fiber. While flowering, beggar-ticks are a butterfly and bee magnet, providing both nectar and pollen. In addition to plants, a crucial component of healthy wetlands is invertebrates (dragonfly larvae, snails, beetles, worms). These tiny creatures are an important food source for waterfowl and fish. Specifically, during spring migration the diet of female ducks consist mainly of invertebrates which provide necessary protein and other nutrients for egg production. Native plants, such as arrowhead and duckweed provide the required underwater structure for invertebrates to thrive. Over time, the composition of wetland plants will shift. Without disturbance, a shallow wetland will transition from diverse high-quality habitat to monoculture stands of willows, cottonwoods and brush.
Wetlands are dynamic systems that require constant disturbance. Without disturbance, the plant community shifts to perennial species that are less desirable to waterfowl. Historically, wetlands would have received disturbance through flooding, fire, wildlife use and other natural events. Today, we mimic natural disturbances through management actions, such as disking, mowing, prescribed fire, managing water and applying herbicides. These management actions help to maintain early successional habitat which produces the most duck food and benefits other wildlife and pollinators. Disking is an important practice used to promote annual moist soil plant production and to maintain early successional habitat. Disking can also be used in conjunction with other disturbance techniques to control undesirable species, such as reed canary grass and cattails. Winter disking will expose these plants roots to freezing temperatures and reduce spring growth. Strategic mowing and prescribed fire are highly valuable and inexpensive ways to provide disturbance and reduce weed competition. Mowing eliminates cocklebur seed production and reduces light competition, allowing native moist soil plants to thrive. Mowing, in combination with reflooding is highly effective in controlling cocklebur. Approved herbicides are another management tool and can be tremendously effective, particularly when used in combination with other management techniques. Herbicides should be used as part of an integrated pest management plan to reduce invasive and undesirable species. Cattails, for example, are a beneficial wetland plant that can become a nuisance. Without disturbance cattails can quickly dominate a wetland plant community. Appropriately timed herbicide applications, prescribed fire and strategic flooding can revert a cattail engulfed wetland into beneficial open habitat.
While native plants are essential to healthy wetland habitats, non-native and invasive species can quickly destroy a functioning wetland. The key to invasive management is preventing an infestation. Act quickly to prevent the spread of invasive species and use a variety of techniques to treat and control undesirable species. There are two management methods to control any invasive species: mechanical and chemical. While chemical methods of control (ex. herbicides) are often the first choice, these means of management are not the “easy button.” First and foremost, anyone using chemical control methods must follow the product labels. If the plant you are trying to control is not listed on the herbicide’s label, do not use that herbicide. If your target species is listed, use the label specified amount of herbicide. The correct percent of herbicide in an applied solution is critical to control. Too much herbicide, and you may not effectively be treating the target. Timing is also crucial. Some herbicides are only effective in the spring, while others must be applied in the fall. The most effective way to control invasive species is using a multi-faceted approach. Create a management plan that uses a variety of proven control methods, such as mowing, prescribed fire, herbicide use and water level manipulation. There are resources available to assist in directing invasive species management actions, including the Midwest Invasive Plant Network.
Water Level Adjustments
The ability to adjust water levels in a wetland can aid in reaching conservation goals and management objectives. Wetland managers often draw down water level in the spring or summer to promote the growth of moist soil plants. Both conservation goals and management needs can determine the timing of drawdowns. If conservation goals are to benefit breeding ducks, lowering water level during early spring migration can help to concentrate invertebrates, providing easy feeding area for migrating hens. A complete early dawn down may be beneficial for management reasons, particularly if the objective is to disk the wetland. Mid-season draw down can reduce weed competition, whereas water may be held later in the season to control woody species growth. In addition to the timing of drawdowns, the speed at which water is removed is important to consider. Slowing dewatering (approximately 1 inch or less per day), will yield the greatest diversity of plants. However, management objectives may require water to be removed quickly. The timing and speed of removing water is as equally important to putting water back in the wetland. Throughout the growing season, it is important to maintain high soil moisture. In drought conditions, this may require reflooding or flushing wetland management areas. During spring and fall migration, the goal of flooding a wetland should be to provide a variation of water depths from mudflats to deep (not to exceed 13 inches) open water while birds are traveling through. To achieve varying depth, most wetland managers slowly flood or dewater. A good rule of thumb is to target water depths from ½ inch to 12 inches, reaching a fully flooded unit by peak migration. Each type of bird requires a different water level to feed. Teal, for example, tend to feed in shallow water depths of 2 to 7 inches. If a conservation goal is to provide foraging habitat for teal, a management action should be to flood 15 to 25 percent of the unit to varying depths between 2 to 7 inches during teal migration periods. For real-time predictions of bird migrations, check out BirdCast and the Forbes Biological Station’s aerial surveys.
To obtain high quality wetland habitat and reach conservation goals, a variety of management actions must be applied. Wetlands are ever changing ecosystems that require consistent disturbance. Applying the right disturbance technique at the right time and adapting to necessary management needs will yield high quality habitat (i.e. lots of duck food). This article skims the surface of wetland management. Be sure to check out these additional resources: the Illinois Department of Natural Resources’ Shallow Wetland Habitat Management and Wetland Vegetation Management and the U.S, Fish and Wildlife Service’s Wetland Management for Waterfowl Handbook.
If you’re interested in restoring wetlands in east-central Illinois, contact Jason Bleich at firstname.lastname@example.org to get started. If you’re interested in restoring wetlands in the Illinois River Valley or western/southwestern Illinois, contact Emily Hodapp at email@example.com. If you’re interested in restoring wetlands in northwestern/northern Illinois, contact Scott James at firstname.lastname@example.org.
Jason Bleich is a Private Lands Biologist for the U.S. Fish and Wildlife Service (USFWS) in Illinois. He has worked with private landowners the majority of his 13-year career in natural resources, including Pheasants Forever and the Ford County Soil & Water Conservation District. Originally from Illinois, Bleich has had the opportunity to work in multiple states including Arkansas, Iowa, and Missouri before returning to his hometown in east-central Illinois. Bleich is excited to continue working with Illinois landowners and conservation partners in his role with the USFWS Partners for Fish and Wildlife Program,
Emily Hodapp is a Private Lands Biologist for the U.S. Fish and Wildlife Service in Illinois. Hodapp works with conservation partners and landowners throughout the Illinois and Mississippi rivers areas to produce more duck food while also promoting Boltonia decurrens, a federally threatened plant species. In addition to her work on the rivers, she tackles hill prairie restorations which benefit the monarch butterfly, pollinators, northern bobwhite, migratory songbirds and more. She also works with private landowners to restore ephemeral wetlands for breeding Illinois Chorus Frogs, migrating waterfowl and quail.