Identifying invasive plants on the trails.

by Emily Wiederkehr Rothschild and Phyllis Chinlund


THERE’S BEEN A LOT of recent buzz around invasive plants. In December, the State of Maine approved regulations to ban the commercial sale of 33 species of common invasive plants. These regulations beg the questions: What is an invasive species, and why should we care?
An invasive plant is one that is not native to a particular ecosystem or geographic area and whose introduction is likely to cause harm to other plants and animals. Of the roughly 2100 plant species in the state of Maine, about one third are non-native, though only a fraction are reported to cause harm to our landscapes. The introduction and growth of invasive plants threatens the regeneration of Maine’s forests,
increases the cost of agriculture, negatively affects recreation opportunities, and can even decrease property values. In Maine’s urban areas, there are increasing amounts of these dangerous plants growing in yards, parks, and on the trails.

So how do these invasive plants do so much harm on our trails? According to Daniel Bishop, Portland Trails Stewardship
and Trail Volunteer Coordinator, “Some species are obvious when looking: Multiflora rose and Bittersweet are climbing vines that can literally choke out native plants, especially trees. Others, by nature of their growth patterns, can crowd out and out-compete native plants for sunlight and space. For example, Phragmites grows in dense patches. Once it takes hold, it grows taller than the natives around it, blocking their
ability to get sun and other nutrients. Over time they displace natives and decrease biodiversity, and biodiversity is a key indicator of environmental health.” Invasive plants can affect
animals as well. They can eliminate animals’ food supply, change ground cover, and reduce opportunities for nesting.

Click the gallery to learn about four common invasives we find on the trails.

Getting a handle on the spread of invasive plants is an important part of Portland Trails conservation work. We choose to remove them manually, without the use of chemicals, which is a labor-intensive process. With only two full time staff on the trails, our resources are limited in how much we can do. However, you may have seen some of Portland Trails invasive management strategy in action if you crossed by the Phragmites monitoring boxes in the marshes of the Fore River Sanctuary. Daniel Bishop is also working on putting a new Invasive Species Management Plan into place for the future of the organization. “Our new plan will look at things systematically, and focus our efforts where we can have the biggest impacts with our limited resources.”

Invasive plants are a huge ecological problem to combat. Land trusts and conservation organizations can only improvethe lands they manage. Private landowners’ actions also have a deep effect on landscapes and the natural environment. And, climate change exacerbates the spread of invasive plants. Highly flexible invasive plants have been found to adapt to changing environs better than some native varieties, and therefore they threaten biodiversity even more.

But, there are a number of things you can do in your own life to help:

  • ■ Plant only native species in your yard or garden; encourage your landlord or property managers to do the same.
    ■  Ask your local greenhouse or nursery to include more native plants in their inventory.
    Volunteer with Portland Trails and augment our existing workforce that is combating invasive plants on the trails. Want to help out? Email for more info!