Invasive Species Spotlight: English Ivy
English ivy doesn’t belong in Rock Creek Park! Thanks to an army of volunteers, there’s hope of reversing its centuries-old invasion.
Created by Erin Ziegler, Explore Natural Communities Intern Summer 2015, NatureServe.
Special Thanks to Rock Creek Park's Ana Chuquín, Division of Resource Management, National Park Service.
Sounds: Scary Ambiance, by Mike Koenig (soundcloud.com); Incoming Suspense, by Maximilien (soundcloud.com) // Music: Lord of the Land, by Kevin MacLeod (incompetech.com) Licensed under Creative Commons: Attribution 3.0
Photo: Red Admiral on English Ivy, by Matt Jones. Licensed under Creative Commons: Attribution-NonCommercial 3.0
Podcast time: 2:31 minutes
It's in your park, it's in your forests—it might even be in your front yard!
English ivy is a ground cover that is causing big problems all over Rock Creek Park. English ivy (Hedera helix) originated in Europe, Asia, and northern Africa, but it spread to North America with the colonial settlers in 1727 when it began its invasion of the natural communities here.
English ivy got its start when people planted the vine in their gardens to fill in shaded areas. However, once English ivy starts to climb, it doesn't stay put in the garden. As soon as it is allowed to grow vertically, the ivy produces flowers and berry-like fruits. Birds eat the fruit and soon start spreading seeds everywhere as they fly. Before you know it, little English ivy patches spring up everywhere, making their way into natural communities and outcompeting local plants for sunlight, nutrients, and space.
As it grows, English ivy can cover whole trees in its search for light, arborizing—or becoming its vertically growing form—as it climbs. Biological Science Technician Ana Chuquín from the Division of Resource Management works to protect Rock Creek Park from problem plants like English ivy.
According to our vegetation surveys, about 19% of the park is covered by English ivy. When English ivy arborizes it starts growing thick hair-like structures and getting water and nutrients from the area right underneath the bark of trees. As a result, this behavior damages the trees and can end up killing the tree.
The English ivy grows up trees, making them top-heavy and prone to collapsing in the wind. Even though some birds love English ivy for its dark purple fruit, others, like wood peckers and owls, can't find nesting sites in hollow trees as this troublesome vine topples the dead trees they need.
Things may look pretty bleak for native species because of a simple garden plant, but it's not too late! You can help the National Park Service by finding patches of English ivy and alerting park staff about it or by joining a volunteer event to help pull invasive species from Rock Creek Park.
Even at home, you can help stop the spread by planting native species like Virginia creeper (Parthenocissus quinquefolia – [beware: also a vigorous grower!]) or trumpet vine (Campsis radicans) in your garden, or by making sure that your English ivy never climbs or blooms. It'll take a lot of work, but we can keep our parks and natural communities weed-free.