We’ve all seen those amazingly tall reeds with the feathery seed heads that glow in the autumn sunset and last right through the winter, and which have appeared in dense stands on roadsides wherever there’s a bit of water.
Those beautiful reeds are phragmites, and they’re deadly to nearly every other plant, bird, amphibian and predator in our wetlands.
That was the message in a sobering talk by Janice M. Gilbert on April 19. Since there are two big marshes in my neighbourhood, and phragmites are scattered widely in this area, I was keenly interested.
The species of phragmites (pronounced frag-mite-eez) that is causing so much concern is the European common reed. Though it is closely related to a native variety of phragmites, the European version has no natural controls in North America and quickly multiplies into a dense monoculture.
Dr. Gilbert has been researching phragmites and working in phragmites control efforts for the past 10 years. She spoke at the Purple Woods Conservation Area this week, in an event sponsored by Scugog Environmental Advisory Council in partnership with Central Lake Ontario Conservation, Kawartha Conservation, North Durham Nature, Scugog Lake Stewards and Nature Conservancy of Canada.
Gilbert explained that the European common reed is awesomely prolific because nearly every part of the plant will sprout and grow if dropped in wet soil.
It produces a large seed head, and the seeds can be carried for kilometers by the wind – but that’s just one of its strategies for dispersal. Its rhizomes shoot out for many feet in every direction. And if a live stalk is knocked down, it will send up new shoots all along its length.
Dispersal methods of phragmites. (From Invasive Phragmites – Best Management Practices in Ontario)
This explains why phragmites have spread so widely along highways and rural roads. Heavy equipment used in road construction and maintenance, particularly tracked machinery, carries mud from one site to another. If pieces of phragmites are carried in that mud, and it doesn’t completely dry before being dropped in a new location, a new outbreak of the reed will soon be growing.
Spread of phragmites in the Great Lakes area. (From Invasive Phragmites – Best Management Practices in Ontario)
Habitat destruction
Phragmites take over a location so rapidly because they suck up nutrients and water faster than nearly all competitor plants, and because they are allelopathic – their roots secrete chemicals which are toxic to other plants.
Native insect species have not evolved to feed on phragmites – and that means insect-eating birds don’t find food in a phragmites monoculture. Muskrats don’t like phragmites, so they don’t build their characteristic mounds, surrounded by a bit of open water, within phragmites-dominated marshes. Birds will nest right around the edges of phragmites stands, but not very far within – the stands are too dense. And since a fully-developed phragmites monoculture can have 200 stalks per square meter, the growth is so dense that turtles trying to fight their way through are sometimes trapped, succumbing to starvation.
In short, the entire food chain from bottom to top is disrupted when phragmites take over a wetland.
A tale of two marshes
This ecological horror story is of more than passing local concern. There are two important coastal wetlands in my neighbourhood. In one of them – Westside Marsh – there are already major stands of phragmites all along the west side.
Phragmites are established all along the west edge of Westside Marsh, next to the St. Marys Cement quarry. Photo from Nov 2015.
The other local marsh, Bowmanville Marsh, appears to be phrag-free so far – but there are stands of phragmites barely 100 meters away.
This stand of phragmites is along West Beach Road, just north of Bowmanville Marsh.
A stand of phragmites on the south side of Hwy 401, near the Liberty Street exit, extends to within a few meters of Soper Creek. This creek flows south and joins Bowmanville Marsh.
A long and difficult battle
The good news is that phragmites infestations can be controlled. The bad news is that the process is labour-intensive, it sometimes requires specialized equipment, efforts need to be repeated at least two or three years in a row, and it is almost impossible to get large stands of phragmites knocked back without application of concentrated glyphosate.
Dr. Gilbert described her own gradual conversion to advocating the use of glyphosate – as a wetland ecologist, her first reaction was to recoil at the thought of using herbicides around wetlands – and her frustration that the glyphosate formulations used to great success in phragmites-control programs in the US are not usually available or permitted in Canada.
In our local area, Diana Shermet of Central Lake Ontario Conservation Authority (CLOCA) confirmed that to date, there have been no phragmites-control programs in Westside Marsh or Bowmanville Marsh. High cost is a major barrier, though CLOCA has received funding and carried out phragmites-control programs in a few areas in Durham region.
As Gilbert noted, successful phragmites-control efforts are usually co-ordinated between several agencies. It does little good to get phragmites out of a marsh if there are stands a few meters away along roadsides. And it does little good to get phragmites out of a ditch along a municipal road, if there are stands along a regional or provincial highway nearby.
The Ontario Phragmites Working Group is providing information and expertise to agencies across the province, and we certainly hope that the provincial government, Durham Region, Municipality of Clarington and CLOCA will find a way to take up this effort in the near future.
Top photo: a stand of phragmites in Westside Marsh, photographed in April 2017. (Click here for larger version)