Leah Harrison, Natural Resources Volunteer Coordinator
Spring is the time for wildflowers in Michigan, but it is also a time for spring invasives. Invasive plant species are one of the first plants you will see in the spring, popping up and growing leaves right as our native plants are just starting to get going. The worst spring offenders are garlic mustard (Alliaria petiolata) and dame’s rocket (Hesperis matronalis). These European natives contain allelopathic chemicals that leach into the soil and prevent seeds of other species from germinating. This allows the plants to create thick monocultures in the forest understory and degraded grasslands, choking out any native species trying to grow. What’s so bad about a field full of flowers? A monoculture means a loss of biodiversity, which is important in supporting a stable ecosystem for native pollinators and other animals.
The Natural Resources Department hosts several volunteer days in the spring to target these early invasives. While there are many invasive plants on Metroparks property, we target garlic mustard and dame’s rocket in the spring because of their short life cycle. Both plants are biennials, growing a rosette the first year and blooming and going to seed the second. Garlic mustard starts growing early in the spring, flowering in early May and going to seed by mid-June. Dame’s rocket begins to bloom in late May, going to seed in late July. If these plants are not removed before they go to seed, they release thousands of tiny seeds that spread and can create bigger and new infestations. The Metroparks uses the help of volunteers to pull these plants out by the roots and then disposing of them so they cannot re-root or develop and release their seeds. Even underdeveloped seeds from these species can still germinate! Each spring, we return to sites with volunteers to pull invasive species. Returning every year and not letting new invasive plants go to seed exhausts the soil’s seed bank and allows native plants to germinate and reestablish. Once an area has been visited enough times, we can turn our focus to new natural areas in need of help.
So far, this year, your Metroparks has hosted 297 volunteers who have donated 670 hours to help remove 3,780 pounds of garlic mustard and dame’s rocket from 45 acres of natural areas! We are so grateful to our volunteers who help make the Metroparks more beautiful. Volunteers allow us to visit and impact more areas than we would be able to do alone. Removing invasive species makes room for natives to reestablish and form more resilient communities. If you would like to help your Metroparks in the fight against invasive species, please click here. You can also help by landscaping with native wildflowers. Do your research before buying plants and be skeptical of “wildflower” seed mixes, which often contain many exotic flowers that can easily escape your yard and threaten native plants. To sign up for Volunteer Natural Resource Opportunities Click Here.