Protecting wetlands and birds from the invasion of the standing dead

Thursday, March 12, 2015

Masters student Courtney Robichaud taking bird counts in a stand of Phragmites at Long Point Marsh, Ontario.

Reaching up to 15 feet tall, Phragmites australis, is invading our roadways, shorelines and wetlands. Choking out other species and destroying habitats across the country, the aggressive wetland reed has been called “worst invasive plant in Canada”.

In the last twenty years, invasive species have surpassed pollution and habitat destruction as the number one cause of wetland degradation across the Great Lakes region.

Biology Professor Rebecca Rooney and master's student Courtney Robichaud in the Faculty of Science are investigating how bird communities are responding to the invasion of Phrag, as it’s commonly called, in Lake Erie’s Long Point marsh. The marsh is a critical habitat for rare migrating and nesting birds.

Invasion of the standing dead

Phrag, came from Europe and arrived in North America through the St. Lawrence River in 1916 but rapidly expanded in the 1990s. It hitches rides on trucks or any piece of machinery carrying soil. Just a piece of root is enough for it to easily establish itself and become a plant.

Because Phrag is so tall, it shades out other plants even after the plant dies in place, creating a culm of “standing dead” stems.

While Phrag stems shade and cool the soil, affecting what grows and survives in the soil, their root systems can reach nearly two metres below ground and have a lateral spread of tens of metres. These roots release toxins that keep other plants from growing.

This has a cascade effect on basic soil processes, allowing Phrag to create a microclimate that kills native plants and impacts animal life as well.

Waterloo scientists define impact on wetlands

Phragmites sketch

Previous studies show a changing distribution of native versus invasive plants, which must be managed actively to maintain wetland biodiversity and native bird populations.

While the soil and microclimate effects are well documented, few researchers have looked at bird breeding areas.

Historically Long Point was dominated by marsh meadow and cattail plant communities. These are being replaced by invasive Phrag, and this is affecting the bird community composition in the marsh.

Rooney and Robichaud’s bird habitat research is also looking at the ecological effects and management of Phrag in the marsh. In Long Point, Phrag has spread from 17 hectares in 1995 to a record 137 hectares in 1999.

They plan to spend a second season collecting bird counts next summer which will be used to continue restoration efforts and wildlife management currently underway.