Gulf Voices                                              Printer friendly format                               Phragmites…on the move By Lois Winter Last fall, a friend of mine watched a duck hunter driving north on I-95 with a pick-up truck loaded with Phragmites. Also known as common reed, the tall perennial wetland grass thrives in sunny wetlands, in brackish or fresh water. Presumably the plant was intended for camouflaging a hunting blind in a Maine wetland. En route, Phragmites seeds were blowing away in the wind, perhaps to germinate in roadside wetlands. Also last fall, on a site visit to one of our recently completed restoration projects, I gasped when I saw a newly constructed duck blind covered with Phragmites in the center of the 100-acre [40-hectare] site. Then there is the story of the Little River Marsh, one of Maine’s most pristine salt marshes—no ditches, no culverts, no fill and no invasive plants. Several years ago, I worked with state agencies, local and statewide land trust partners and willing landowners to secure substantial federal funds that helped permanently protect that marvelous marsh. Last year, one of our partners discovered a duck blind covered with Phragmites while walking that site. I have watched people cutting Phragmites at the edge of a roadway, with an eye to decorating their home with the distinctive and lovely plant. Clearly, even people who care about Maine’s salt marshes are not well in-formed about Phrag-mites, an invasive plant that has severely compromised the integrity of salt marshes to our south, and threatens the biological values of salt marshes in Maine.

Non-native Phragmites

No one knows how far north Phragmites might extend, and whether or not it will overwhelm Maine’s native salt marshes, as it has overwhelmed marshes to our south. But signs are ominous. Just ask Phil Bozenhard, a regional biologist for the Maine Department of Inland Fisheries and Wildlife. “There were only two small stands of Phragmites located on the seaward side of Scarborough Marsh on Route 1, 25 years ago,” he recalled recently. “Today, Phragmites has taken over large sections of the marsh upstream of Route 1, and sizeable stands have become well-established in Cascade Brook, Libby River and the Nonesuch—three of the five large subwatersheds within Scarborough Marsh.”

Phragmites sports an attractive plume of flowers and can grow up to 18 feet high [5.5 meters]. The plant spreads by seed or by sending out new shoots from underground stems, called rhizomes, or from above-ground runners called stolons. Once established, a new stand of Phragmites expands primarily, but not exclusively, by its rhizomes and stolons.

Non-native Phragmites can take over rapidly, blocking out the native salt marsh assemblage of plants and animals and obliterating critical pool and panne habitat that offer refuge and feeding grounds for fish and waterbirds. Phragmites can also create a dense jungle of vegetation that furbearers, deer, many native salt marsh birds and even people cannot penetrate. Huge annual accumulations of Phragmites dry and fall to the ground and decompose. Decomposing Phragmites raises the surface of the marsh, reduces high tide flows, decreases salinity, lowers the water table and generally makes the marsh surface even more appealing to the growth of Phragmites.

Then thereâs fire danger. Phragmites÷with abundant tinder-dry plant material that dies back each fall÷increases the potential for catastrophic fire on the marsh and on surrounding uplands. Genetic studies have confirmed that a native Phragmites exists in North America. Phragmites rhizomes have been found in 3,000-year-old peat samples collected from East Coast marshes. Historically, Phragmites was rare, non-invasive and grew in mixed plant communities. In the early 19th century, a non-native and highly invasive strain, most likely European in origin, appeared in coastal ports in the eastern United States. The rapid spread of non-native Phragmites in the 20th century was likely related to the construction of railroads and major roadways, habitat disturbance, shoreline development, pollution and eutrophication. Recent research confirms that non-native Phragmites can outcompete and displace native Phragmites and can spread to areas where the native strain never grew. Today, invasive Phragmites is scattered across North America and dominates pockets of the Atlantic coast where few native populations remain. The most definitive way to distinguish native and non-native Phragmites is to conduct a genetic analysis, but subtle physical characteristics can also help distinguish the strains. For more clues about the physical differences refer to the text box below or to the University of Marylandâs Center for Environment Science Web site at www.ian.umces.edu/pdfs/ iannewsletter7.pdf.

Once established, controlling Phagmites is challenging, to say the least. Mowing alone is unsuccessful; it may actually increase shoot density in subsequent years. Burning alone is also unsuccessful. Some combination of repeated flooding and cutting may work. However, on some marshes, it may be impractical to restore a natural flooding regime, and where Phragmites is well established, restoring natural flooding alone may not be sufficient to halt its spread.

Methods to eradicate Phragmites is a topic of much debate. Some experts, like Mike Morrison, president of SWAMP, Inc., a salt marsh restoration contractor, believe that “carefully applying herbicides and then mulching the dead Phragmites to make room for native plants to take root, seems to be a successful control method.” The herbicide is effective because it translocates the toxin into the Phragmites rhizomes.

Whatever approach we use to limit the spread of non-native Phragmites, we need to recognize environmental factors that contribute to its spread. Adds Sandra Lary, a biologist with the U.S. Fish and Wildlife Service’s Gulf of Maine Program, “Only if we deal with the symptoms that made the marsh attractive to Phragmites in the first place can we have a realistic hope of keeping Phragmites under control.”

For example, by increasing tidal flow to increase salinity, dense stands of Phragmites may be outcompeted by plants that better tolerate saline conditions. Working with nearby landowners to increase the width of riparian buffers, and improve upland management practices can reduce freshwater and phosphorus/nutrient inflow on the marsh, eliminating conditions that favor Phragmites. By removing fill, we can also eliminate environmental conditions that favor Phragmites.

Salt marshes represent one of Maine’s rarest habitat types, constituting only 0.4 percent of Maine’s wetlands. For hundreds of years, ditches, dikes, roadways with inadequate culverts and fill have compromised the biological integrity of our salt marshes. In more recent years, the mushrooming of residential developments along the marsh fringe has only compounded the problem. Now, Phragmites threatens our salt marshes, but in fundamentally different ways.

To maintain the beauty and wonders of our natural world in the Gulf of Maine watershed, salt marshes deserve our careful and mindful stewardship.

Lois Winter is a conservation biologist and outreach specialist with the U.S. Fish and Wildlife Service Gulf of Maine Coastal Program.

 © 2004 The Gulf of Maine Times