The Phragmites Problem: Aggressive invasive reed threatens wetland ecosystem processes

Monday, January 16, 2017

Phragmites

Byline: Sarah Kim, Biology MSc. student

Wetlands in North America are home to a very diverse set of native plants. But an invasive reed called common reed (Phragmites australis) has been expanding rapidly and could potentially threaten the ecosystem processes in the wetlands it inhabits.

Sarah Yuckin, a Master’s student in Prof. Rebecca Rooney’s lab at the University of Waterloo, is studying the invasive lineage of common reed to understand how its presence and current restoration efforts affects ecosystem processes in Noth American wetlands.

Invasive common reed produces extremely tall plants that can reach up to 16 feet in height. Although there is a native lineage of common reed that occurs naturally in North America, an invasive lineage from Europe has spread rapidly from multiple points of introduction on the east coast and has quickly emerged as a threat to local vegetation.

Common reed has been called the number one invasive species to wetlands in North America,” says Yuckin. “And they reproduce clonally.

The problem with common reed is that it is capable of outcompeting native plants, ultimately resulting in decreased biodiversity and insufficient supply of habitat and food. Important ecosystem processes such as vegetation decomposition, nitrogen cycling, and greenhouse gas emission can also be affected by these invasive reeds. Common reed can also multiply in large numbers so quick action is required to prevent irreversible changes to wetlands across North America.

In order to determine whether invasive common reed is causing any changes to wetland ecosystems, Yuckin performs what she calls a “litter bag transplant experiment”.

A litter bag transplant experiment measures the decomposition rate of different litter types in three vegetation communities - uninvaded meadow marsh, uninvaded cattail marsh and marsh invaded by common reed. Litter bags are filled with either native Canada bluejoint grass, cattail or common reed and randomly placed in these communities.

After a few months, these bags are brought back to the lab to be analyzed on how the community and litter type affected the rate of decomposition. Measuring the decomposition rate can give information on how the specific litter quality from the different plant species affects important ecosystem traits, such as nutrient availability to neighbouring plants.

Their presence can lead to a chain of detrimental effects including changes to nutrient cycling and carbon storage.

Yuckin is in the first term of her Master’s studies, and is currently collecting data in Long Point Peninsula from her litter bag experiment. After completing her analyses from this experiment, Yuckin plans to visit areas where common reed has been managed, namely in coastal wetlands on Lake Erie, and observe the effects of restoration on decomposition there.

NOTE: BIOL 690 Scientific Communication is a graduate course that helps students enhance their skills in the acquisition, organization and presentation of scientific information. Students in the course interviewed and wrote a news story about one of their classmates' research.