The Ecology and Management of Prairies in the Central United States

8. Examples of Management Systems

There are numerous tools and strategies available for managing prairies, including prescribed fire, grazing, mowing, haying, herbicide application, and rest. When trying to promote biodiversity, you should consider using a variety of these strategies. Following are several generalized examples of management systems. They include examples of systems without cattle and/ or fire, but, when feasible, the combination of fire and grazing can be a key component of a diversity-friendly management regime. If both fire and grazing are available to you, you should still read the other examples, because they are written to provide cumulative advice. In other words, management strategies that don’t require fire and grazing can still be used to complement or supplement a fire/grazing system. These examples will not cover some issues , such as invasive-species challenges, in detail. However, invasive species will be dealt with in the next chapter, and strategies to deal with them can be incorporated into most of these systems. Management without Fire or Cattle If neither fire nor grazing is feasible at your site, find other ways to simulate the desired impact of those disturbances. Mowing and/or haying can be used to defoliate growing plants and to prevent an excess buildup of thatch from suppressing plant growth. The difference between mowing and haying is that prairie management 8. Examples of Management Systems 92 prairie management haying involves the removal of the cut material. In many cases, haying is preferable since thick swaths of cut hay lying on the prairie can kill the vegetation underneath them. If you do mow, doing it when the prairie vegetation is still fairly short can reduce the possibility of smothering plants under excessive litter. Raising the mower deck and cutting higher can do the same thing. Because it removes the cut vegetation from the site and doesn’t allow it to decompose, repeated haying can slowly diminish the nutrient content of the soil, especially the phosphorus, potash, and nitrogen, with mixed results. Loss of nutrients can reduce productivity, but lower levels of nitrogen, in particular , can help increase plant diversity by favoring forbs over grasses. Extra nitrogen from years of fertilization or deposition from nearby agricultural fields can assist the invasion of exotic cool-season grasses. In Europe, biologists are finding that multiple decades of annual haying can actually improve plant diversity by reducing nitrogen levels that favor a few dominant plants. In North America there are prairies that have been hayed annually for years and have maintained a strong and diverse plant community. This is especially true for prairies that are hayed late in the season, after most plants have had an opportunity to flower. However, annual haying can also have a number of disadvantages, especially if cutting is done at the same time each year. One big disadvantage of haying (and mowing) in a diversity-friendly management system is that it is nonselective. Every plant species is cut to the same height when the mower comes past, as opposed to the selective grazing done by cattle or other grazers. Just as clear-cutting does in a forest, haying homogenizes the vegetation structure of the community, and repeated haying can sometimes reduce plant diversity. You can help mitigate this in a prairie by taking advantage of the fact that plants grow and bloom at different times of the year. For example, mowing the prairie in early June will have a strong impact on the vigor of cool-season grasses and early-season forbs that are just preparing to bloom. They will have expended a great deal of energy preparing for flowering and will lose all that energy when they are mowed off. By contrast, most warm-season grasses and late-season flowering forbs will just be getting started, and will easily recover from an early-season mowing. Likewise, mowing in August will have little impact on plants that have already flowered and become dormant for the year, but will affect severely those 93 examples of management systems just preparing to flower. Cutting hay in the late summer can also favor coolseason grasses (including many invasive species) by increasing the amount of sunlight available during their fall and spring growth periods. Mowing during the dormant season (November through March) can remove thatch and standing dead vegetation from the prairie without having any immediate impact on plant vigor (except for that of shrubs and trees). In addition, as most prairie plants enter dormancy...