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Invasive plants: the Common Reed

Its name tells you maybe nothing, but you probably heard, either along the Lachine Canal, a highway in southern Quebec or newly cleared land. The Common Reed or Phragmites, is a plant species having the greatest spread in the province in recent years. The phenomenon worries biologists and annoys farmers. What is it exactly?

Description

This large plant forms dense colonies in wetlands (marshes, riverbanks, lakes, ditches along highways) with upright stem can reach 1.5 to 2 , 5m high. The inflorescence is a large panniculus feathery whose color varies from greenish yellow to reddish brown. Reproduction is done in 2 ways:

• sexually, by seed dispersal;
• vegetative propagation by rhizomes and stolons * **.

common reed are found on all continents except Antarctica. If this is 3000 years in North America, only since the late 1950s he took a remarkable expansion in south-western Quebec. For example, the Boucherville islands, its progress has been meteoric. Absent from the region in 1970, this plant now occupies nearly 250 000 m2 and seems ever expanding. (1) is a European genotype, so exotic, introduced in recent centuries, however, that causes the problem, in addition to disruption of natural environments such as dredging, excavation, landscaping, etc.. Indeed, the disturbed soil are ideal for the spread of warbler.

Impacts of the spread

Flora

The areas invaded by the Common Reed is often dense and impenetrable. The multiple means of reproduction allow it to reproduce on average 3 times faster than native vegetation. It easily adapts to periods of flooding and drying while tolerating large variations in temperature. Over time, it alters the hydrology of the soil by evapotranspiration *** and because it forms a thick litter ground which is 3 times thicker than that of native vegetation, thus covering the water and preventing the growth of other plants. Therefore, this plant is very resistant, tolerant and aggressive ranks among the worst invasive plant species difficult to control.

Wildlife

research can not currently determine the impact suffered by wildlife. However, based on some observations, the accumulation of litter Warbler and the high density of rhizomes prevent fish from moving into the affected areas. Witness the Northern pike spawn 3 times less than in marshes invaded by the warbler. In the long term, more and more space will be occupied by the warbler, reducing the area of spawning fish. This is true for bird species that need water to breed. The only relevance of the warbler for wildlife is protected, the only one in early spring season. Otherwise, some species of mammals such as muskrats eat the rhizomes.

Solutions management and prevention

In Canada, use herbicides is banned, prompting the search for environmental solutions. Given the aggressiveness of the plant, or planting the seed of native species near the sites of warbler is insufficient. It should rather excavate the area to remove all rhizomes and remove the excavated material to a landfill or, where appropriate, an area already invaded Warbler. The intervention must be done before August lorsqu'ont place seed formation and germination. Then, the excavated area must be immediately seeded or planted with trees or shrubs. A shrub band, however remote it may be, would prevent the Warbler to expand because the shadow and the physical barrier created enough to prevent the progression of rhizomes and stolons. Another technique, currently being tested, is covered with a thick opaque linen excavated areas and to sow seeds of an optimal mix of native plants to inhibit the growth of warbler.

Definitions *
rhizome: Part underground or underwater stem that contributes to setting the plant in the ground, sinking into the ground and branching, allows multiplication of the plant . ** Stolon: Body plant consisting an aerial stem that grows at ground level and, at the nodes, gives birth to a new plant. When the new seedling is autonomous, the stolon dies. *** Evapotranspiration: The water lost in the air from both the surface soil and plants.

Sources

BRIGHT, R. AND DUMONTIER, M. (January 30, 2010). Green Week: A threat, the reed warbler? , http://www.radio-canada.ca/ [Online]. http://www.radio-canada.ca/audio-video/pop.shtml # = urlMedia http://www.radio-canada.ca/Medianet/2010/RDI2/LaSemaineVerte201001301801_1.asx Accessed September 8 2010.

Godmaire , H. Côté and , S. (2006). Do you know this exotic invader? The common reed. http://www.nature-action.qc.ca/ [Online]. http://www.nature-action.qc.ca/nature_action/pdf/Evee/Roseau% 20commun.pdf

LAVOIE, C. (June 2008). Invasion of Phragmites along the road corridors : Current situation, causes and management , Transportation Studies and Research for the Department of Transport Quebec, the Quebec Government. http://www.mtq.gouv.qc.ca/ [Online]. http://www.mtq.gouv.qc.ca/portal/page/portal/Librairie/Publications/fr/ministere/recherche/etudes/rtq0802.pdf

Ministry of Agriculture, Fisheries and Food Quebec (2009). Weed Management: Common Reed . http://www.mapaq.gouv.qc.ca/ [Online]. http://www.mapaq.gouv.qc.ca/Fr/Productions/Protectiondescultures/mauvaisesherbes/fichesmauvaiseherbes/PhragmiteCommun.htm Accessed July 19, 2010.

Credit: Jacques Brisson