Long term management

Management of Phragmites doesn’t end after the initial treatment. Management strategies should be maintained over multiple years to substantially reduce Phragmites populations. However, repeated management treatments may also result in a temporary deterioration of habitats. Chemical control, in particular, while generally considered the most efficient form of control, will also lead to a degradation of resident species when applied at a broad scale. As a result, the increased resource availability (e.g. sun, space, nutrient) and decreased competitive pressure can facilitate the reintroduction of Phragmites or other undesirable invasive species. Phragmites seeds will remain viable in the seed bank for a few years, and seedlings are likely to appear in years following the treatments. An effective management plan should allocate sufficient resources to encompass the costs associated with restoration efforts and long-term monitoring of the targeted site. Another aspect of management is continuing education. The U.S. Fish and Wildlife Service uses a series of learning modules titled: Volunteers and Invasive Plants to help volunteers better understand and manage invasive species.

Resources:

  • Galatowitsch, S. M., D. L. Larson, and J. L. Larson. 2016. Factors affecting post-control reinvasion by seed of an invasive species, Phragmites australis, in the central Platte River, Nebraska, Biol Invasions. doi 10.1007/s10530-015-1048-3. Full Paper
  • Peter, C. R. and D. M. Burdick. 2010. Can plant competition and diversity reduce the growth and survival of exotic Phragmites autralis invading a tidal marsh? Estuaries and Coasts, 33(5): 1225-1236. Abstract
  • Carlson, M. L., K. P. Kowalski and D. A. Wilcox. 2009. Promoting species establishment in a Phragmites-dominated Great Lakes coastal wetland. Natural Areas Journal, 29(3): 263-280. Abstract

Restoration

Open, humid soils that are free of vegetation and receive direct sunlight present optimal conditions for the germination of Phragmites seeds. Experimental studies have demonstrated that the risk of Phragmites re-introduction can be substantially decreased by planting or sowing native species, particularly in areas where Phragmites have been established in a monoculture for many years and few naturally occuring native seed sources are available nearby. Results were considerably enhanced when higher diversities of native species were used to restore sites, as more diverse ecosystems tend to be more resilient to invasion. Native species with fast growth rates and good covering capacities are the best barrier against Phragmites, as they rapidly occupy empty spaces.

Resource:

  • Byun, C., S. de Blois and J. Brisson. 2013. Plant functional group identify and diversity determine biotic resistance to invasion by an exotic grass. Journal of Ecology, 101(1): 128-139. Abstract
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Ongoing monitoring

Management sites should be frequently visited for monitoring native plant recovery and early detection of Phragmites seedlings or missed stands. Rapid response to isolated stands can considerably reduce the costs of management efforts. Moreover, it is important to control seedlings before they start to reproduce sexually and further contribute to the seed bank. Long-term monitoring should also take into account potential surrounding sources of Phragmites seeds or fragments. Identifying adjacent populations of Phragmites and potential vectors of Phragmites (e.g. roads, rivers) is an effective way to evaluate the risks of re-introduction. Prevention is often the most cost-effective way to manage invasive species. It is crucial continually monitor sites and to limit the growth of Phragmites stands around managed habitat to prevent the establishment of new colonies.
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