Northern Prairie Wildlife Research Center
U.S. Fish and Wildlife Service, Office of Information Transfer, 1201 Oak Ridge Drive, Suite 200, Fort Collins, CO 80525
A frequent objective of managing cattail marshes is to reach and maintain hemi-marsh conditions. Identifying the successional stage of a wetland is the first step towards determining the appropriate direction of subsequent management. Generally, all wetlands with cattails in their flora mimic aspects of the prairie marsh cycle. However, certain hydrologic conditions can lengthen the duration of any stage to such an extreme that no cycle is apparent.
Cattail (Typha spp.) management and control efforts should be based on the principles of cattail autecology, with the annual cycle of carbohydrate storage and conversion being particularly important. When cattails are dormant, control techniques such as cutting over the ice depend on impeding oxygen transport to the rhizomes via aerenchyma. This will affect subsequent conversion of carbohydrates. If carbohydrate reserves in the rhizomes are insufficient to allow spring shoots to emerge through the water column to air, they will not survive.
Nonchemical control techniques during the growing season such as discing are most effective when done during a 3-week window from one week before to one week after the pistillate spike is lime green and the staminate spike is dark green. This is when carbohydrate reserves in the rhizomes are at their annual minimum.
Cattails can produce seeds and contribute to the seed bank at all marsh stages, but recruitment occurs only during the dry stage. Light in combination with other environmental factors is critical to germination, and 13 mm of water filters out enough light to prevent germination. Long-term changes in water regimes in a marsh can have either subtle or drastic effects on plant species composition. Cattails, being best adapted to semipermanent water regimes, can be eliminated by deeper and more permanent water levels. Likewise, a conversion to a drier water regime (e.g., a seasonal marsh) can shift the competitive ecological edge to other species.
Fire can be used to control cattails by destroying the aerenchyma link between leaves and rhizomes, but only if followed by high water levels in spring. For management by fire, most cattail marshes must be burned in winter or before significant growth has occurred in spring when fuels are dry enough to carry a fire. However, frozen or saturated soils can hamper the progress of fire through cattail duff. Grazing by cows, geese, muskrats (Ondatra zibethicus), and other animals on seedling and young cattails without extensive rhizomes can remove entire plants, reducing stem densities or eliminating stands. The season of grazing and the water levels in subsequent seasons determine to what degree plant vigor is diminished through the combined effects of removing the aerenchyma link between rhizomes and leaves, stressing carbohydrate storage, and stressing starch conversion.