About Phragmites
he Common Reed, Phragmites australis, is the workhorse of Reed Bed technology (it has been referred to as "the sewage treatment plant"). A perennial grass that grows 6-12 feet tall, it was originally native to Eurasia and Africa, but can now be found distributed throughout the world. It is found in various wetland environments, such as fresh water and brackish marshes, swamps, and along stream beds. It has also been spreading into areas where human activity has exposed soil and created areas of poor-drainage, such as along highways and railroad rights-of-way.
P. australis is ideally suited to use in Reed Beds because of a number of specific characteristics:
- it prefers slightly-to-very wet conditions (in other words, it loves sludge!);
- it is a robust plant and can tolerate a fairly wide range of pH and salinity;
- it grows quickly, creating vast amounts of leave surface area, allowing it to evaporate off (transpire) prodigious amounts of water;
- as its lower stems become buried under deepening amounts of organic matter (e.g., sludge) it sends off secondary shoots from higher up on the stem.
Although Phragmites has been here in North America for at least 40,000 years, in somewhat recent history the reed has become more aggressive, spreading more quickly and displacing other "native" plants, in some cases creating near monoculture (single specie) stands. This "invasion" seems to have been taking place slowly but steadily over the past 150 years, with an apparent acceleration over the past few decades. Recent DNA studies explain this "change in propagative behavior" by pointing the finger at the introduction of a "new," non-native genotype sometime in the 1800s.1 The more recent acceleration in Phragmites' spread has been blamed on increases in certain human activities, such as:
- Construction (e.g., road building) activity that has served to distribute Phragmites rhizomes, allowing for a greater degree of proliferation than would have been the case otherwise;
- Similar human activity that has resulted in new areas of un- or poorly-drained, disturbed soil (favorable conditions for Phragmites to take hold);
- Tidal control projects that have resulted in decreased salinity in coastal marshlands (Phragmites is tolerant of somewhat brackish water); or...
- ALL OF THE ABOVE!
Community concern about the creating of Reed Beds using Phragmites is not uncommon. While not nearly as aggressive as some other non-native invaders (e.g., kudzu, "the vine that ate the south"), such concerns are not completely without merit. The following information may be helpful in assuring the public that Reed Beds are not likely to contribute to local problems with Phragmites. Some key points:
- While they do produce seeds which may be distributed small distances by wind and over larger distances by birds, Phragmites reeds spread almost exclusively through vegetative (rhizomal) propagation. The concrete free walls, gravel beds and PVC linings which completely enclose Reed Beds effectively eliminate any opportunity for the plants to spread beyond their boundaries. And whether through seed distribution or rhizomal propagation, without adjacent areas of un- or poorly-drained, disturbed soil there is really no significant risk;
- With over 150 installations (120 still in continuous operation) in 17 states, Reed Bed Systems, Inc. has not had any reports nor received any complaints about the spread of P. australis beyond the sludge treatment facilities;
- Phragmites australis has become extremely wide spread in North America, particularly in the northeast. So, in the hypothetical, even if propagation from Reed Beds was likely (which it is NOT), the beds would still play a negligible-to-insignificant part in contributing to the problem.
Finally, it should be remembered that Reed Beds are an effective, low-tech form of bioremediation for the treatment of municipal and others sludges. Reed Bed Technology is an effective process using plant life to help in the necessary process of treating some of the byproducts of human communities. And it does so in a way that:
- reduces energy consumption;
- helps to mediate the dispersal of heavy metals into the environment;
- absorbs excess nitrogen and phosphorous that might otherwise contribute to the eutrophication of ponds and lakes;
- ...all while saving communities money!
Click the photo below to view a case study of a Reed Bed Installation in Maryland that clearly demonstrates the extreme unlikelihood of Phragmites propagation by wind-borne seeds.
Click Here for Maryland Case Study
Click here for larger view of this
circa 1800s botanical etching
of Phragmites communis
(a close relative of P.autralis).
Go to our Photo gallery
to view photographs of
Phragmites australis and
various Reed Bed Systems
installations.
1. Saltonstall, K. Cryptic invasion by a non-native genotype of the common reed, Phragmites australis, into North America. Proceedings of the National Academy of Sciences, 2002. 99, 2445-2449.