Description and Biology

Common Reed, or Phragmites australis, is an alien, invasive plant with origins in Europe and Asia. While there is a native variety, it appears to be much less aggressive and harmful than its alien counterpart. Common Reed has recently found its way to some of Lake Huron's beaches and has raised much concern amongst the public and the scientific community.

Most frequently, Common Reed colonizes a new area from small fragments of rhizomes, dispersed by water, animals, machinery and humans. Once established, new upright stems grow from underground rhizomes and a colony begins to spread vegetatively.

Do not disturb the rhizomes. Breaking them up may result in an increased population and encourage its spreading.

Rhizomes spread horizontally in all directions during the growing season. Flowering begins in late June, and seeds are formed by August. In early autumn, food reserves move from leave and stems to the rhizome system. The leaves die and fall off, with only the dead brown vertical shoots remaining. The accumulation of dead leaves and stems, as well as the pervasive rhizome system, prohibits the growth of desirable plant species.

Common Reed generally has annual cane like shoots that reach heights of 2 to 4m and disperses by seeds or rhizome fragments. Rhizomes are responsible for renewing and maintaining the population; a single plant spreads at a rate of 1-2m per year. The dead canes remain standing for 3 to 4 years before becoming part of the slowly decomposing litter layer.

In a recent study of this invasive plant at Long Point on Lake Erie, Common Reed abundance increased with lower lake levels and was reduced with higher water levels.

Also, air temperature played an important role in Common Reed abundance. Higher air temperatures led to increases in abundance. Air temperatures over the last decade have been on an upward trend in southern Ontario.

Common Reed expansion in the past 4 years on Lake Erie was exponential. Reasons for the rapid growth are unclear but lower water levels and a warmer climate may explain the change.

Threats

Scientists are concerned that the growth of this plant in beach areas could negatively alter dune ecology and displace the rare native species found in Lake Huron's dunes. The displacement of native species and the formation of dense monocultures also have negative impacts on insects, birds and other species that rely on intact dune habitats.

Control

Once established, common reed is very difficult to completely eradicate. However, careful planning and long-term management can produce satisfactory results. Invasive populations of Common Reed must be managed in order to protect rare dune plants that it might outcompete, valued plants and animals whose habitat it might dominate and degrade, and healthy ecosystems that it might greatly alter.

Cutting has been used successfully to control Common Reed. Since it is a grass, cutting several times during a season, at the wrong times, may increase stand density. However, if cut just before the end of July, most of the food reserves produced that season are removed with the cut portion of the plant, reducing the plant's vigour. This regime may eliminate a colony if carried out annually for several years. Care must be taken to remove cut shoots to prevent their sprouting and forming stolons. Stalks and seed heads must be either bagged and removed from the site, or burned to ensure that seeds are destroyed.

ADDITIONAL INFORMATION:

Field Guide for the Control of Common Reed (Phragmites australis) on Lake Huron Beaches - revised 2008
The establishment of Common Reed along the Lake Huron coastline is extensive. Small stands, and often extensive patches of Common Reed have been observed in a variety of coastal habitats. Although Common Reed thrives in coastal meadow marshes, it has also established along open sandy beaches, and in sand dune habitat where it can access the water table. Common Reed can displace rare species in good quality dune habitat. This can lead to the alteration of dune ecosystems, which could ultimately lead to beach and dune degradation. (16 pages)

Occurrence of Common Reed (Phragmites australis) on Lake Huron shorelines: Field Report and Recommendations
The purpose of the fieldwork described in this report was to determine the extent and severity of Phragmites australis establishment along the Lake Huron shoreline from Point Clark to roughly Southampton. Where possible, the coastline between Southampton and Sauble Beach was also surveyed. With locations known, a secondary purpose was to suggest additional areas for control, especially where Phragmites was replacing existing open sand dune or sand beach habitat of good quality. Completed by Holly Bickerton for The Lake Huron Centre for Coastal Conservation - November 2007 (40 pages)

Invasive Reeds in Lake Huron: The Water Chronicles - Special Feature - 11/20/2007
Listen to the Coastal Centres' Geoff Peach talk about the Common Reed, an invasive European reed that is threatening a number of native plant species, some rare, and some endangered. Courtesy water.ca - November 2007. (~6 mins)