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Invasive Assault of Phragmites australis on Michigan Ecosystems
Long Lasting Effects and Destruction of Habitat
Although there are many varieties of Phragmites, one particular version has been brutally degrading our wetlands and disturbed areas across Michigan. It has appeared on the shorelines of all the Great Lakes. Some of the most prolific stands are found on the Saginaw bay and St Clair delta. This type of common reed is robust and out-competes other varieties that are native to the continental U.S. Also in danger are many other shoreline plant species that are integral to the health of our natural habitats. Creating a monoculture, these grasses do not allow for other species to grow. Not only do they spread extremely fast, but they are not easy to get rid of. Extreme measures and long term commitment by wildlife officials are specifically needed to help slow down the progress of this rapidly moving invasion.
The Explosive Spread of Phragmites
Unlike many other non-native species that were intentionally brought to America for ornamental or useful purposes, Phragmites was most likely carried along by accident. Speculation about its transport includes common ways that invasive species throughout history have been introduced to foreign lands. Many are relocated in packing materials or in ballast water. The common belief is that it must have arrived as early as the 1700's. First being recognized in Boston and New York, it creeped its way along the Atlantic coast presumably driven by storms. By 1950 the march across the U.S. caused it to be noticed as it replaced other plants in wetlands and along highways. Intrigued by the intense displacement this plant created, it was discovered that this was a genetically different variety from our native type. Recently, a subspecies has been created dubbing our native type as americanus. Surveys of late have shown that the non-native version has migrated across the entire continent with some exceptions in southern states and the extreme north.
Growing to heights of 6 to 15 feet Phragmites blocks out views and takes over the muddy areas between water and land. Due to the broad leaves and clumping nature, all other plants are deprived of sunlight that prevents germination of native species. 80 percent of the plant is underground in the form of rhizomes and growing to a depth of 6 feet. This makes eradication difficult. One plant can produce 2000 seeds annually but is usually spread by these rhizomes especially when stems are disturbed by cutting which only makes their regrowth more robust.
One of the most alarming aspects of the spread of this plant is the damage done to waterfowl and migratory birds. Ducks lose their nesting grounds and many birds lose their food source. Native plants attract insects that are critical to some species for survival. Wherever Phragmites has become established, the amount of other species has declined. The toxins that are released by this plant are so toxic that they breakdown the proteins in the roots of other plants in a process called allelopathy. The competition is so fierce that native plants do not stand a chance.
Methods of Elimination
There have been several types of procedures attempted to help eradicate this invasive, but many of them have not had success. Millions of dollars have been spent in studies to determine what kind of actions should be taken. Mowing or cutting them down only encourages greater growth the next season. Digging or pulling them out results in broken up pieces left in the ground that develop into new plants. Prescribed burning over several years seems to help but you must get a permit or a professional for this strategy. It seems as if the best effort is the "clip and drip" method. Cut and bag the stems for removal. Immediately drip the pesticide into the stem carefully to avoid over polluting the waterways. This is the best technique for removal.
© 2014 Jimmy Mitchell