Invasive plant threatening shoreline

Invasive plant threatening shoreline
Common reed could squeeze out native plants
Posted By Jim Algie
Updated 3 hours ago
Low water in Lake Huron has created an opening for an invasive non-native reed which appears to be moving north from areas of infestation in southern Bruce County and threatens beach dunes and wetlands, the Lake Huron Centre for Coastal Conservation says.

More aggressive than its native reed cousin, phragmites Australis — more commonly known as common reed — grows to a height of about 1.5 metres and has a large, feathery plume. It forms thick rhizome mats and could choke out a variety of endangered species in sensitive dune areas along Lake Huron’s Bruce County shore, researcher Geoff Peach said in a recent interview.

“These are vulnerable ecosystems anyway. This invasive plant adds an additional challenge to conserving our coastline,” said Peach, the manager of the non-profit Lake Huron Centre for Coastal Conservation. The centre, based in Blyth, conducts research, education and community outreach projects.

Centre researchers documented phragmites infestations in Huron-Kinloss and Saugeen Shores this summer and experimented with eradication methods in a $29,000 project funded by Environment Canada’s Invasive Alien Species Partnership Program.

The project also includes developing an eradication manual for landowners and municipal governments, which Peach expects will be completed soon.

“This is a very opportunistic plant,” Peach said, and the low water levels have created large open beaches and an opening for the reed, which can “take advantage of the situation so it gets a foothold.”

Common reed outcompetes established plants and poses a threat to rare coastal beach and dune species such as American beachgrass and Great Lakes wheatgrass. Peach is particularly concerned about the threat to the endangered Pitcher’s thistle, a dune plant which is found sparingly in Bruce County and on Manitoulin Island.

Common reed has likely been present on the Lake Huron shore for about five years. However, it has taken off within the past two years, Peach said.

The centre’s report recommends urgent cutting at several sites with small infestations. It also recommends that it makes more sense to completely eliminate common reed from one area rather than to partially eliminate it from many. It also makes sense to eliminate common reed from the best quality, least infested areas first to allow the reestablishment of native plants.

Eradication can be tricky, Peach warned. The plant grows through root rhizomes and mechanical tillage or inadequate root excavation may just help the plant reproduce.

“We saw somebody using a Rototiller and grinding up a bunch of the plants in an effort to try and get rid of it on a shoreline property,” Peach said. “The problem is that the plant spreads through its roots and if you chop up each one into fragments it can grow into another plant.”