Invasive Species in Portland

Click the images below to learn more about these invasive species and why they can be so disruptive to our native plants and animals here in Portland.  

Invasives_Asiatic Bittersweet_Icon Opens in new windowInvasives_Autumn Olive_Icon Opens in new windowInvasives_Black Swallowwart_Icon Opens in new windowInvasives_Bull Thistle_Icon
Invasives_Callery Pear_Icon Opens in new windowInvasives_Glossy Buckthorn_Icon Opens in new windowInvasives_Japenese Knotweed_Icon Opens in new windowInvasives_Multiflora Rose_Icon Opens in new window
Invasives_Norway Maple_Icon Opens in new windowInvasives_Phragmites Common Reed_Icon Opens in new windowInvasives_Rosa Rugosa_Icon Opens in new windowInvasives_Shrubby Honeysuckles_Icon Opens in new window
Invasives_ Burning Bush_IconInvasives_Japanese Barberry_Icon Opens in new windowInvasives_Garlic Mustard_Icon


What we do & why we do it

The Forestry division of the Parks and Recreation Department is dedicated to the preservation of our city's unique and important habitat. To help ensure that our native plants and animals thrive, we have been aggressively removing several invasive species from green spaces across the city. 

What is an Invasive Plant?

Invasive plants are those which are not native to a region, and which cause harm to the environment, human health or degrade habitat.  Non-native plants out compete native flora interrupting the food web and reducing habitat values.  

Where did they come from?

Many of the plants on the invasive plant list were brought in decades ago due to their fruit, flower and ornamental characteristics. Invasive plants spread via a higher adaptability and prolific seeding, some change soil chemistry or leaf out before and after native vegetation.

What is being done?

The Forestry Division's first steps are inventory and setting goals: establishing management strategies using manual, mechanical, bio-control and chemical control when needed. Research suggests that a combination of methods work best. Portland’s Parks and Open Spaces have varying degrees of invasive plants with ongoing inventory and control methods at work. Defending native plant communities from being overrun by invasive plants, reducing seed sources by manual and mechanical methods is our first goal.  

How you can help:

Residents can help by following these two important items: 

  • Improving their own properties removing invasive plants and replacing with alternative native plants. 
  • Volunteering

Portland Parks, Recreation & Facilities and Portland Parks Conservancy partners with a number of local organizations, including land trusts and neighborhood groups to improve the environment.  Most of our Casco Bay Island neighborhoods have active invasive plant programs. Public education is a key component of this effort, we routinely work with Maine Audubon, Portland Schools, Public Works Water Resources and Portland Trails including our Park Ranger and Park Conservancy programs.   

Successful invasive plant strategies requires persistence, knowing it can take several years to remove, monitor and replace with native plants.  It all starts with survey and planning.

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Portland Parks Conservancy 

Invasive species removal projects from 2021

In 2021 the Portland Parks Conservancy was able to hold 54 different volunteering events where they had over 90 volunteers help tackle this very real issue within our city. Thanks to their efforts, they were able to remove invasive plants in 14 different locations across the greater Portland area!

Here are some numbers, detailing the hard work put in during 2021

  • 406 Volunteering hours
  • 9,690 gallons of invasive plants removed
  • 5,814 lbs of green matter
  • 2,855 square feet covered

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If you would like to volunteer, please see the link below:

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