Wetland Conservation and Management for the Texas Central Coast

Vegetation Management

The most productive and desired vegetation communities in wetlands respond positively following a disturbance. Soil disturbance, such as disking, is the most important management action to promote the growth of desired plants that produce food for waterfowl. Other disturbance treatments are also effective at manipulating wetland plant communities and increasing wetland use by waterfowl and other waterbirds.

Disking: Soil disturbance from disking can control unwanted plant species and encourage the growth of annual plants that produce abundant seeds consumed by waterfowl. Disking soil as early as possible following a late winter or early spring drawdown will promote seed germination in the current year. If wet conditions persist, disking soil in summer or fall will prepare the site and promote annual plant growth for the next growing season. In addition, disking in late summer followed immediately by shallow flooding provides open foraging habitat for migrating shorebirds. Disking wetland units is recommended at least once every 3-4 years, as production of annual plants tends to decline each consecutive year without soil disturbance.

Mechanical disturbance such as disking (left), shredding and roller-chopping (right) are important management actions that can improve wetland quality for waterfowl.

Shredding and Roller-chopping: After wetland units become dry, shredding can be used to enhance wetland plant communities. Shredding during the growing season can reduce stands of undesirable plants, such as sumpweed (also known as marsh elder) and sesbania, and promote growing conditions for more favorable plants. Shredding rank stands of vegetation may be necessary prior to disking. Shredding and roller-chopping is used to promote an even balance of open water and vegetative cover in a wetland. Research has demonstrated that waterfowl and other waterbirds tend to prefer wetlands that have an interspersion of open water and vegetation at or near a 1:1 ratio (i.e.; “hemi-marsh”). Shredding vegetation in fall prior to flooding an impoundment can create open areas in dense vegetation. After a wetland is flooded, roller-chopping may be necessary to provide and maintain open water areas.

Prescribed Fire: Prescribed fire is an efficient method of reducing rank and dead vegetation and controlling invasive woody plants in dry wetlands. Fire also can be used to achieve a “hemi-marsh” condition in a wetland. In fall and winter, fire applied on coastal emergent marsh and prairies promotes new growth of plants. With timely rainfall, geese will use recently burned marsh and coastal prairies to feed on the fresh growth of cool-season grasses, sedges and other emergent plants. Adequate fire breaks and specific weather conditions are required to safely and effectively use fire.

Prescribed fire and cattle grazing are treatments that mimic natural disturbance and can be used as a means to efficiently manage wetland habitats.

Grazing: If mechanical disturbance is deemed too expensive, livestock grazing can be used as an alternative in certain instances. Trampling of the ground by grazing livestock can have an effect on plant communities similar to light disking. However, livestock will eat many of the plants that produce food eaten by ducks. Thus, applying high stocking rates over a short period of time (depending on size of treatment area) can achieve the desired effect without detriment to beneficial plants. Conversely, geese prefer open areas for foraging, loafing and roosting that can be achieved with livestock grazing over a longer term.

Applying herbicide to control vegetation
can include use of crop dusters (top)
and boom-spraying rigs (middle) for
large areas and spot treatments
of individual plants (bottom).

Herbicide Control of Invasive and Non-native Plants: Invasive plants typically have little or no value for waterfowl and are capable of creating large, dense stands of vegetation. Cattail and spiny aster are good examples of invasive plants that can take over large areas in a wetland. Non-native plants, such as Chinese tallow tree and deep-rooted sedge, also can form dense stands and compete against desired native wetland plants. All of the aforementioned disturbance treatments provide some level of control on the growth and encroachment of invasive and non-native plants. However, when these noxious plants become the dominate species and cover a significant portion of a wetland unit, it may be necessary to consider treatment with a chemical herbicide product. Some herbicide products are more effective than others for controlling a specific plant or group of plants. In some instances, a combination of herbicide and other disturbance treatments may be required to achieve the desired effect. Not all chemical herbicide products can be applied in or near a wetland. Chemical herbicide treatment of vegetation in or near a wetland requires the use of specially certified products generally indicated on the label. Chemical herbicides should always be applied at the recommended rate as described on the label.

Wetland managers at TPWD Wildlife Management Areas (WMAs) have experience implementing many of the treatments described above on different wetland habitats under various conditions. The goal of habitat management on WMAs is to promote quality habitat for the benefit of wildlife and provide a strong base of knowledge to support wildlife management and conservation on private lands. Examples of vegetation management under different scenarios conducted on WMAs in the Central Coast can be downloaded here: Common Treatments Used to Control Vegetation in Wetland and Grassland Habitats on Wildlife Management Areas in the Texas Central Coast

Additional resources for controlling common nuisance plants