The dark side of the forest: why some trees do more harm than good

The Norway maple (Acer platanoides) is an invasive species that can produce abundant seed, form dense monocultures and outcompete other species. 

Most of us learned about the benefits of trees early on – whether through an Earth Day school curriculum or Arbor Day public service announcements during Saturday morning cartoons. Messages like “Trees are always good!” and “Any tree is a good tree!” spread far and wide. And with that mindset, why would anyone ever want to remove one? The answer might surprise you.

Picture this: There’s a beautiful tree in your back yard. It provides shade during the summer, its leaves turn vibrant colors in the fall and birds build their nests in its branches in spring. But as time goes on, the tree starts to weaken and lean dangerously over your house. You call in an arborist, who advises that, for safety, the tree needs to be removed. Most people would agree that this is a necessary step to protect both the home and family.

Just as a leaning tree can threaten a household, invasive tree species threaten local ecosystems. They crowd out native plants, reduce species diversity and disrupt the delicate balance that supports wildlife. For these reasons, and as part of its ongoing commitment to conservation, Summit Metro Parks will begin a conservation maintenance project this October to remove invasive tree species at three Metro Parks: Firestone Metro Park, Goodyear Heights Metro Park and Munroe Falls Metro Park.

The Threat of Invasive Species

Invasive trees (species that can invade natural or seminatural areas) may be beautiful, but don’t be fooled by their appearance. When they’re not actively harming the environment, they’re often not contributing much good, either. Why does this matter? Non-native trees typically host very few native wildlife species. For example, a single native oak tree can support up to 500 species of native butterflies and moths, as well as thousands of other organisms, such as fungi, lichens, and mosses. In contrast, a Norway maple might host fewer than 10. This disparity has a cascading effect on our local ecosystems, contributing to the decline of native species and the health of our parks.

Spicebush swallowtail by Sheila Stransky

One example of the negative impacts of invasive trees like the Norway maple is the effect on our native spring wildflowers, such as trillium and mayapple. These plants rely on sunlight during the brief period before trees leaf out in spring. Unfortunately, Norway maples leaf out approximately two weeks earlier than native species, shading out and devastating our native woodland wildflowers.

white flower blooms among brown leaves
Photo of trillium by Joe Prekop

what to expect

Among the most common invasive species we will be targeting are the Norway maple and tree of heaven. Other species, including Callery pear, sweet cherry and white mulberry, may also be removed as part of this initiative.

The removal of invasive trees at Goodyear Heights Metro Park will occur in phases, starting  October 15 through the end of the year. The park district does not anticipate any project-related park or trail closures. Subsequent phases will follow in the coming years.  Visitors can continue to enjoy all the amenities our parks offer while SMP works to restore the ecological integrity of these parks, ensuring their wellbeing for many years to come.

Following the invasive tree species removal, the area will be monitored to determine the best course of action for reforestation. While we are optimistic natural regrowth will occur, the park district is prepared to support the process with the seeding of native tree and plant species in the future.

How You Can Help

Invasive plants and trees spread easily, often with the unintended help of human activities. You can play a crucial role in supporting our efforts by incorporating native plant species in and removing invasives from your own outdoor space. By choosing native plants, you help reduce the spread of invasives and create a healthy habitat for local wildlife. To learn more about how you can help through the park district’s Wild Back Yards initiative, visit bit.ly/wildbackyards.