Vectors and Dispersal
List of Topics
- What is the distribution of Phragmites?
- How does Phragmites reproduce?
- How does Phragmites spread?
- What enables Phragmites to outcompete other plants?
- What factors promote invasion by Phragmites?
- What are the current research questions about Phragmites?
- What can you do to prevent the spread of Phragmites?
- Principal sources
What is the distribution of Phragmites?
Phragmites australis is an aggressive invasive species with a widespread distribution in freshwater wetlands around the globe. It can be found throughout the continental U.S.A. and is commonly found along the Great Lakes.
- During the recent low water levels in Lake Michigan and Lake Erie (1999-2004) it has spread significantly into the newly exposed lakebed, forming large clones which exclude virtually all other plants (Whyte et al., 2008).
- It dominates Great Lakes marsh in Saginaw Bay and the St. Clair delta.
How does Phragmites reproduce?
Phragmites reproduces by sprouting from a seed or rhizome fragment although it most often spreads underground through the rhizomes.
- It quickly colonizes open sunny areas, especially roadside ditches and heavily disturbed sites that have altered hydrology, sedimentation and nutrient enrichment (especially nitrates) or high salinity (Jodoin et al. 2008).
- It also can invade native, sunny wetlands with moist soil or shallow water and shorelines along lakes but does not spread as easily on sites with dense, established vegetation (Wisconsin Wetlands Association, 2004).
- Phragmites tolerance of flooding frequency, level, and duration varies by site. Voss (1972) reported that common reed occurred in water up to 6 feet deep in Michigan.
- Once a new Phragmites stand takes hold it spreads primarily through vegetative reproduction. (Meyerson 2009)
- In Wisconsin, the lateral spread of the rhizomes in Phragmites stands averaged 40 cm (15.7 inches) in a year and can grow to 70 feet (20 m) in length (Curtis, 1959).
- Stolons (above ground horizontal stems) produced in young stands or over open water, can grow 4.25 in (10.8 cm) per day (Uchytil (1992) reaching lengths of up to 43 feet (13 m) (Larson, 1993) and further aid in rapid stand expansion.
- Seed viability is quite variable and dependent on a variety of factors.
- Although seed viability is thought to be quite low, large patches with greater genetic variability often have increased seed viability. (Kettenring et al. 2010). In at least some cases, flowers from cross-pollinated populations produced significantly more seed than self-pollinated flowers. (Ishii and Yoshuro, 2002).
- According to some sources, Phragmites may need to reach 3 or 4 years of age before producing viable seed (Cross and Fleming, 1989).
- A wide range of germination rates are reported in the literature under varying conditions:
- Phragmites seeds appear to germinate at higher rates in full light on the soil surface, at warm temperatures and under moist but not saturated conditions (Gucker, 2008)
How does Phragmites spread?
Newly disturbed sites can be colonized by seed or rhizome fragments carried to the area.
- Humans can transport seed or rhizome fragments in soil, on machinery during construction and landscape maintenance and through the use of recreational vehicles such as ATV's (Marks et al. 1993).
- Seed and rhizomes can be carried naturally in floodwaters (Marks et al. 1993). and by lake currents and wave action.
- Seeds are dispersed by wind (Wijte and Gallagher 1996) and by birds, especially red-winged blackbirds that nest among the reeds (Benoit and Askins, 1999; Haslam 1972).
- Although currently illegal in Michigan, Phragmites has been used in the past in wetland rehabilitation and stabilization projects to revegetate disturbed areas, to stabilize river banks and control shore erosion and deliberately planted for boat covers, wildlife cover and duck blinds (Uchytil (1992).
What enables Phragmites to outcompete other plants?
Phragmites possesses many ecological characteristics which promote its ability to invade new areas, its adaptability in varying conditions, and its capacity to outcompete other plants. These characteristics enable Phragmites to spread, force out other species and form dense stands.
- It can survive and even thrive in stagnant waters where the sediments are poorly aerated. Air spaces in the above ground stems and in the rhizomes provide the underground parts of the plant with a relatively fresh supply of air (Haslam 1970).
- It is readily adapted to variable water levels (Haslam 1970).
- Its tolerance of salinity allows it to grow where few other plants can survive (Vasquez et al. 2005).
- The build up of litter from the aerial shoots and the dense mats formed from the rhizomes and roots discourages other species from germinating and becoming established (Haslam 1971).
- Phragmites does have a low tolerance for wave and current action that can break its vertical stems and hinder bud formation in the rhizomes (Haslam 1970), although rhizomes can be carried and spread to new areas through these same types of currents.
What factors promote invasion by Phragmites?
- The presence of linear wetlands such as roadside agricultural ditches, the use of road salt, ditch digging and the agricultural input of nitrogen (Jodoin et al. 2008).
- Road construction (Lelong et al. 2007; LeBlanc et al., 2010)
- Lowered water levels, exposed soil and the availability of nearby seed, rhizomes or stolons, or existing populations (Hudon 2005; Whyte, 2008).
- Sparse vegetation - whether due to human disturbance, natural disturbances such as storms and winter ice scouring (Chambers et al., 1999), or sparse vegetation in the particular natural community involved - ie, sand or cobble beach, interdunal swale (MNFI, pers. comm. 2010).
What can you do to prevent the spread of Phragmites?
- Avoid operating earth moving machines or recreational ATV's in the vicinity of phragmites stands to prevent the spread of seeds and rhizome fragments.
- If you plan to disturb wetlands through filling, excavating or vegetation removal, you should consult with the Michigan Department of Environmental Quality to obtain a permit to insure that your project is done in a way that does not harm the environment and contribute to the spread of invasive phragmites.
- If using fill, make sure that it is weed free
- If you would like to control phragmites on your property this may require one or more permits from local, state and federal authorities, as several environmental laws may be applicable. For local ordinances, contact your local municipality for information.
- For state permit information, contact: Land & Water Management Division, Michigan Department of Environmental Quality, Environmental Assistance Center, 1-800-662-9278; firstname.lastname@example.org
- Do not attempt removal:
- through digging or hand pulling (it is ineffective due to the extensive root system)
- disturbing the soil through mechanized disking or raking (it encourages rapid expansion)
- by burning without herbicide treatment prior (it invigorates growth & spreading)
- When removing material
- IMMEDIATELY collect and bag the cut plant material to prevent seed spread. It is important to properly dispose of plant material to prevent the spread of phragmites to other areas.
- Composting is NOT ADVISED since all seeds may not be destroyed in the process
What are some of the information gaps regarding Phragmites? (Meyerson et al. 2009)
- Mechanism of invasion success
- Reproductive biology and propagule survival
- Potential for intraspecific hybridization
- Landscape level analysis of distribution and impacts
- Ecosystem impacts on energy flows and nutrient cycles
- Effects on other species (community composition and structure)
- Appropriate scale of control and effective nonchemical forms of control
- Interaction of introduced Phragmites with other invasive species
- Beneficial uses for Phragmites
- Baldwin, Andrew H., Kettenring, Karin M., Whigham, Dennis F., 2010. Seed banks of Phragmites australis-dominated brackish wetlands: Relationships to seed viability, inundation, and land cover. Aquatic Botany 93 (2010) 163-16.
- Bellavance, Marie-Eve, and Brisson, Jacques, 2010. Spatial dynamics and morphological plasticity of common reed (Phragmites australis) and cattails (Typha sp.) in freshwater marshes and roadside ditches. Aquatic Botany 93 (2010) 129-134.
- Benoit, L. K., and R. A. Askins. 1999. Impact of the spread of Phragmites on the distribution of birds in Connecticut tidal marshes. Wetlands 19: 194-208
- Brisson J, Paradis E, Bellavance M-E (2008). Evidence of sexual reproduction in the invasive common reed (Phragmites australis subsp. australis; Poaceae) in eastern Canada: a possible consequence of global warming? Rhodora 110:225-23
- Chambers, R. M., L.A. Meyerson and K. Saltonstall. 2000. Expansion of Phragmites australis into tidal wetlands of North America. Aquatic Botany 64:261-273.
- Cross, Diana H.; Fleming, Karen L. 1989. Control of phragmites or common reed. Fish and Wildlife Leaflet 13.4.12. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 5 p.
- Curtis, John T. 1959. Aquatic communities. In: The vegetation of Wisconsin. Madison, WI: The University of Wisconsin Press: 385-401.
- Gucker, Corey L. 2008. Phragmites australis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service
- Haslam, S. M. 1970. The performance of Phragmites communis Trin. in relation to water supply. Ann. Bot. N. S. 34:867-877.
- Haslam, S. M. 1971. Community regulation in Phragmites communis Trin. I. Monodominant stands. Journal of Ecology. 59: 65-73.
- Haslam, S. M., 1972. Phragmites communis Trin. Journal of Ecology, Vol. 60, No. 2 (Jul., 1972), pp. 585-610.
- Hudon, Christiane; Gagnon, Pierre; Jean, Martin. 2005. Hydrological factors controlling the spread of common reed (Phragmites australis) in the St. Lawrence River (Quebec, Canada). EcoScience. 12(3): 347-357.
- Ishii, Jun; Kadono, Yasuro. 2002. Factors influencing seed production of Phragmites australis. Aquatic Botany. 72(2): 129-141.
- Jodoin, Y., Lavoie, C., Villeneuve, P., Theriault, M., Beaulieu, J. and Belzile, F. 2008. Highways as corridors and habitats for the invasive common reed Phragmites australis in Quebec, Canada. Journal of Applied Ecology, 45: 459-466.
- Kettenring KM, Whigham DF., 2009. Seed viability and seed dormancy of Phragmites australis in suburbanized and forested watersheds of the Chesapeake Bay, USA. Aquatic Botany 91:199-204.
- Kettenring KM, McCormick MK, Baron HM, Whigham DF, 2010. Phragmites australis (common reed) invasion in the Rhode River subestuary of the Chesapeake Bay: disentangling the effects of foliar nutrients, genetic diversity, patch size, and seed viability. Estuaries and Coasts. 33:118-12.
- Larson, Gary E. 1993. Aquatic and wetland vascular plants of the Northern Great Plains. Gen. Tech. Rep. RM-238. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 681 p. Jamestown, ND: Northern Prairie Wildlife Research Center (Producer).
- LeBlanc, Marie-Claire, de Blois, Sylvie, Lavoie, Claude, 2010. The invasion of a large lake by the Eurasian genotype of common reed: The in?uence of roads and residential construction. Journal of Great Lakes Research 36 (2010) 554-56.
- Lelong, B., C. Lavoie, Y. Jodoin, and F. Belzile. 2007. Expansion pathways of the exotic common reed (Phragmites australis): A historical and genetic analysis. Diversity Distrib. 13: 430-437
- Marks, Marianne, Beth Lapin & John Randall 1993. Element Stewardship Abstract for Phragmites australis. The Nature Conservancy, Arlington, VA
- McCormick, Melissa K., Kettenring, Karin M., Baron, Heather M. & Whigham, Dennis F., 2010. Extent and Reproductive Mechanisms of Phragmites australis Spread in Brackish Wetlands in Chesapeake Bay, Maryland, USA. Wetlands (2010) 30:67-7.
- McCormick, Melissa K., Kettenring, Karin M., Baron, Heather M. and Whigham, Dennis F., 2010. Spread of invasive Phragmites australis in estuaries with differing degrees of development: genetic patterns, Allee effects and interpretation.
- Meyerson, L.A., K. Saltonstall, R.M. Chambers. 2009. Phragmites australis in eastern North America: a historical and ecological perspective. In Silliman, B. R., E. Grosholz, M. D. Bertness. Salt marshes under global Siege. Univ. of Cal. Press, 57-82.
- Michigan Natural Features Inventory, 2010. Personal communication. Stevens T. Mason Building, P.O. Box 30444, Lansing, Michigan.
- Uchytil, R.J. 1992. Phragmites australis. In: U.S., Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Fire Effects Information System. http://www.fs.fed.us/database/feis/plants/graminoid/phraus/all.html. 19 p.
- Vasquez E. A. Glenn, E.Pl, Brown, J.J., Guntenspergen, G.R. and Nelson, S.G. 2005. Salt tolerance underlies the cryptic invasion of North American salt marshes by an introduced haplotype of the common reed Phragmites australis (Poaceace). Marine Ecology Progress Series, 298, 1-8.
- Voss, Edward G. 1972. Michigan flora. Part I: Gymnosperms and monocots. Bloomfield Hills, MI: Cranbrook Institute of Science; Ann Arbor, MI: University of Michigan Herbarium. 488 p.
- Whyte, R.S.; Trexel-Kroll, D.; Klarer, D.M.; Shields, R., and Francko, D.A., 2008. The invasion and spread of Phragmites australis during a period of low water in a Lake Erie coastal wetland. Journal of Coastal Research, SI(55), 111-120.
- Wijte, Antonia H. B. M.; Gallagher, John L. 1996. Effect of oxygen availability and salinity on early life history stages of salt marsh plants. I. Different germination strategies of Spartina alterniflora and Phragmites australis (Poaceae). American Journal of Botany. 83(10): 1337-1342. 
- Wisconsin Wetlands Association, 2004. Emerging issues surrounding invasion and control of Phragmites australis in Wisconsin's wetlands: a survey of wetland professionals. http://www.wisconsinwetlands.org/phragmites.htm