Invasive Exotic Species in Your Woodlot
S&W Report / Fall/Winter 2001, Vol 22

Invasive exotic species continue to plague a large part of southern Ontario's fragmented forests. Faced with an expanding population, these species have the ability to impact the survival of a number of our native species in our woodlots. Without some intervention from woodlot owners, the problem will continue to grow, and our forest ecosystems may be altered.

What is an invasive species? 
They are non-native plants that have the biological ability and/or lack natural control agents that provide these species with a competitive edge to out compete natural species within our woodlots. Table #1 provides a list of the most problematic species found in southern Ontario.

Why are they a threat to our woodlots in southern Ontario?
Our forested landscape is extremely fragmented, transected with a growing matrix of road systems, and are accessed by a high number of seed carriers - i.e. people, cars, ATVs. These elements offer very favourable conditions for these species to become established, to quickly proliferate and ultimately dominate a site. Once established, they can threaten the survival of native species by affecting the establishment of new regeneration and hinder the growth and survival of the species present.

What can be done?
First, woodlot owners need to learn to identify these species while working in their woodlots because the key to minimizing their impact is early detection. Field guides for identifying these species can be purchased at most local bookstores. Newcomb's Wildflower Guide (Newcomb, 1977), Shrubs of Ontario (Soper and Heimburger, 1990), and Ontario Weeds (Alex, 1992) are three guides that are recommended .

There are a number of control measures that can be incorporated into your woodlot management plan that will help minimize the incidence of invasion by these species. Some of these measures include:

-	Minimize mineral soil exposure along trails and forest access roads;
-	Seed is often mixed in with the soil that is embedded in the tread of the tires of the skidder or tractor used in your woodlot. It is recommended you wash the dirt off all equipment before it is moved into your woodlot; and
-	Remove exotic invasive plants when they first appear. They can be easier to control now than in a year or two. By this time, the population may have exploded, and the job may have become larger than you can handle.

Table #1 - Most problematic invasive species that occur in forested habitats in southern Ontario. (1)
Herbaceous Plants	Barberry
	Garlic Mustard
	Dog strangling vine
	Dame's rocket
	Reed canary grass
Trees and Shrubs	Glossy buckthorn
	Tartarian honeysuckle
	Norway maple
	Common buckthorn
(1) Source:  A Silvicultural Guide to Managing Southern Ontario Forests.