The trees, shrubs, and forest floor in your woodland can be a rich, productive, and vital mixture of species. However, sometimes invasive or exotic species - plants and other organisms brought to Maine from elsewhere - can discourage native plants and seedlings you want. Recognizing and dealing early with these species could be a very important task on your property, and could help you realize some of your other goals.
Information on exotic pests and diseases is available from the Maine Forest Services Forest Health and Monitoring Divsion. These agents of damage and disease have already had significant impacts on Maine's forests. The most commonly known example is the near-elimination of American elms by Dutch elm disease - a fungal pathogen introduced from Europe in the early 1900s. However, other insects or diseases continue to have significant impacts today.
Other invasive plants are often overlooked, even though they may be of equal or greater concern than insects or pathogens. Invasive plants, especially woody shrubs, are found in a wide variety of forests, but often take over or out-compete regeneration of native species. Most have been introduced over recent decades as ornamental landscaping plants. Such species can have long-term and far reaching impacts, beyond the area where they are first found. There are treatments available to eliminate these species, but they are often expensive, dependent on chemical herbicides and/or extremely labor-intensive. Eradicating invasive species becomes increasingly difficult the longer they are established. While some of these species can still be purchased at gardening and landscaping stores, planting such species, even in a lawn or landscaping situation, is discouraged, unless you are certain that individuals you have purchased are sterile (cannot reproduce by seeds) and do not propagate vegetatively (from root suckers or sprouts).
Be alert to the presence of these invasive species. Contact your Maine Forest Service District Forester if you need help. Descriptions of the following species and additional information are available from the Department of Conservation's Maine Natural Areas Program.
Invasive plant species found in Maine:
- Multiflora Rose (Rosa multiflora)
- Common Buckthorn and Glossy Buckthorn (Rhamnus cathartica and Frangula alnus)
- Purple Loosestrife (Lythrum salicaria)
- Shrubby Honeysuckles - Tartarian, Morrow, and Belle's Honeysuckle (Lonicera spp.)
- Japanese Knotweed / Mexican Bamboo (Fallopia japonica / Polygonum cuspidatum)
- Asiatic Bittersweet (Celastrus orbiculata)
- Japanese Barberry (Berberis thunbergii)
Aquatic plant species can be equally harmful to native environments, and can be introduced by boats or other recreational gear. Information on invasive aquatic plants is available from the Department of Environmental Protection