Invasive Plants: Threats to Conservation

prepared by PCT land steward Don Eunson

Invasive plants are from other parts of the world: they were brought to New England often intentionally, sometimes accidentally. And then they ran amok.

Invasive plants displace native plants. They often grow faster and out-compete our native plants, stealing nutrients or water or hogging sunlight by their greater size. They take up space without providing food for our wildlife. Some invasives release toxins into the soil that suppress the growth of our native plants.

If you are a gardener you may already know that invasives can take over your garden — crowding out the plants that you want to grow.  Invasive plants are like weeds on steroids.  Some of them are pretty to look at, but they make serious problems for conservation efforts.

We need your help

Provincetown Conservation Trust is launching an effort in 2023 to get rid of invasives. We started with garlic mustard — because it is the very easiest invasive to uproot by hand. It was brought by European settlers as an easily grown food and then it escaped from their gardens. Now it threatens our conservation lands because it secretes something into the soil that interferes with the growth of tree seedlings and wildflowers. It also negatively impacts monarch butterflies because it displaces the milkweeds that monarch caterpillars eat — with something that they do not eat.

There are many invasive plants on Cape Cod that threaten our special conservation lands. Provincetown Conservation Trust is choosing to launch efforts by focusing on a few species that are more manageable to address by hand, without equipment or chemicals.

• Garlic mustard

• Black swallow-wort

• Oriental bittersweet
  

How you can help

1. Remove invasives on your own property.  Don’t decorate with invasives like Oriental bittersweet.

2. Work with the PCT to report and remove invasives on town-owned and PCT-owned conservation lands.
   
   A) Take a walk on any of Provincetown or PCT conservation lands and keep your eyes open for invasive plants. If you see any, take a photo, perhaps a photo that shows where the location is. 
   
   B) Make a note with the photo that describes which PCT property you’re walking in (such as PCT #10) and estimate how far along a path you found the suspected invasive.
   
   C) Send your photo and your estimate of location to PCT at provincetownconservationtrust@gmail.com. We will follow up with an assessment and a plan for action for our volunteers.
   

3. Spread the word. Share this page and information with neighbors and friends to help us contain invasive plants on our conservation lands. 

Oriental Bittersweet

This woody vine can grow to 60 feet long. Its yellow fruits split open to reveal an orange interior. It has been considered very decorative until you know that the vine twines around other trees and shrubs, smothering them in dense foliage and even literally strangling the trunks and killing other woody plants. Very small bittersweet can be hand pulled. Bigger vines require tools that work like levers to uproot them, or cutting and applying herbicides.

Black Swallow-wort

This vine climbs rapidly on other plants and fences, sometimes simply twining on itself for the strength to reach the sun it requires. There is evidence that it interferes with monarch butterfly reproduction: adult butterflies mistake it for the milkweed that their caterpillars eat and lay their eggs on it, but in fact it is not a milkweed. Small plants can be pulled by hand, but to pull the roots some kind of garden tools is required. 

These invasives represent just the tip of the iceberg. We are highlighting these because (a) they have already been seen in Provincetown’s conservation  properties and (b) they can be managed, over time, by volunteers without special equipment.