September 5, 2019 at 11:12 am
By Wildlife Biologist Sarah Spencer
While driving along Maine's roads in early spring, have you ever noticed a shrub in the forest which seems to be green before any other trees or shrubs leaf-out? If you answered yes, then you’ve likely seen the invasive shrubby honeysuckles. While they may be a refreshing sign of greenery after a long, cold winter, an invasion of shrubby honeysuckles can inhibit the forest’s ability to regenerate trees by crowding out seedlings attempting to establish on the forest floor. Covered in flowers, they produce a profuse number of small red fruits by late summer. Between early leaf-out and production of an abundance of fruit, shrubby honeysuckles have a variety of adaptations which allow them to out-compete native plants.
This time of year in Maine, one of the easiest to recognize invasive plants is purple loosestrife (Lythrum salicaria). Native to Europe, this plant’s flowering spike is similar in color to our native fireweed (Chamerion angustifolium), but once you’ve learned to recognize it, you’ll be able to easily tell the difference. While many people enjoy its visually striking flowers, this plant can quickly crowd out native biodiversity our wildlife depend on for food, nest sites, shelter, and other needs.
Although they can be beautiful at first glance, invasive plants can and do wreak havoc on Maine’s landscape when it comes to managing wildlife habitat. An abandoned apple orchard once valued by wildlife for its production of soft mast can become overgrown with the severely invasive Asiatic bittersweet (Celastrus orbiculatus), reducing production of apples and even killing the trees, if left alone with no intervention. Introduced as an ornamental plant, the bright red berries on this vine have been desirable in fall wreaths, but careless disposal and spread by wildlife have allowed it to establish and thrive here.
Biologists, ecologists, foresters, land managers, and other natural resource professionals are constantly looking for these unwelcome invaders. Whether it’s a single plant or well-established stand of plants, each infestation has consequences to the surrounding natural communities and they aren’t just limited to terrestrial environments; there are invasive aquatic plants as well!
There are a variety of factors during the process of deciding whether action will be taken to remove invasive plants. These may include: size of the infestation, how invasive the species is, surrounding natural community, cost, accessibility, etc. While some infestations are small and can easily be controlled by mechanical removal of the plant(s) in a single visit, other infestations may require the regulated application of herbicides specified for control, repeated visits to a site to re-treat, prescribed fire, or a combination of tools.
If you’re interested in learning more about how to identify invasive plants in Maine and what you can do to protect Maine’s natural communities, there are a variety of resources out there to help. A great first stop is at the invasive plants website of the Maine Natural Areas Program at the Maine Department of Agriculture, Conservation and Forestry. Other resources for information include the University of Maine Cooperative Extension and your local Soil and Water Conservation District.