Explore The Ivy FIles and expand your knowledge:
- An Ivy Overview and Why We Remove English Ivy from Natural Areas
Learn the basics of English ivy, and its interaction with our natural areas.
- Ivy Removal Methods
Review the techniques of ivy removal. Familiarize yourself with the field-tested techniques developed by the No Ivy League.
- No Ivy League Project Statistics
See the mind-boggling totals of ivy removed by the No Ivy League and dedicated volunteers.
- No Ivy League Chapters and Other Ivy Removal Groups
Get in contact with a removal group near you or suggest others to be added to the list.
- Knowledge is Power!
Still hungry for more ivy info? Here you'll find important literature regarding ivy removal, other invasive species, and the No Ivy League.
- Ivy Removal Instructional Video
A handy visual guide to our field-tested techniques, perfect for preparing to remove ivy on your own.
- Community Resources
Learn how you can make a difference, view resources available to volunteers who want to remove invasive species from their property or community.
Forest Park is one of America's largest urban forests. Set aside as a natural area within Portland's city limits, its 5,000+ acres are host to over 70 miles of hiking trails and bicycle paths. This natural area provides an unsurpassed opportunities to connect with the forest environment. However, our treasured resource faces a challenge experienced by many natural areas around the globe. Not only are humans changing the physical, chemical, and climactic structure of these ecosystems but we are responsible for the introduction of organisms previously unseen. In the Pacific Northwest (PNW) one such organisms is the plant Hedera helix or Hedera hibernica: often referred to as English ivy.
Members of the Hedera L. genus have long been admired by humans in their historic range throughout Eurasia, Northern Africa, and Macaronesia. The hardiness of these evergreen plants, their tightly weaved vines and intimate relationship with trees led them to become a symbol of vitality and fidelity in Western culture. It is because of this rich cultural significance that we humans have taken ivy, and many other organisms, with us to new lands. The prevalence of Hedera L. in the PNW is primarily due to escape from horticultural uses.
Evidence suggests that modern ivy and its relatives have been present throughout regions of Western Eurasia and Northern Africa for more than 1 million years 1. In this time ivy evolved in the unique ecological niche of a liana, a climbing plant dependent on a host tree for support. Important to these ecosystems, ivy plays an role in nutrient cycling, soil erosion reduction, and animal forage 2. Ivy is highly plastic plant that can grow in a variety of light conditions, soil types and water levels - allowing it to rapidly recolonize disturbed areas as well as succeed in dense forests. The characteristics that make ivy a successful part of its native ecosystems have also made it a successful transplant in the PNW, though its success may be at the cost of our own native species.
English ivy has been observed to dominate the understory of PNW forests, especially in disturbed areas and edge habitat. In these areas the juvenile phase of ivy forms a thick mat of vines and climbs any available surface. This thick mat of vines can prevent significant amounts of light from reaching the forest floor and thus alter the species composition in these areas . As the liana climbs it can reach into the crown of its host tree. A physiological change occurs when the juvenile form has accumulated enough resources, transitioning to a mature form that spirals outward from the trunk of its host tree. Through this process ivy can further block light from reaching the forest floor and in extreme cases from the host tree itself. The mature form of ivy is able to produce berries and distribute seeds, with the help of birds, expanding across a greater range than by vegetative growth alone.
The efforts of the No Ivy League focus primarily on removing mature English ivy from trees in Portland's natural areas to reduce seed distribution and prevent possible damage to mature trees. In a number of areas the No Ivy League also removes substantial amounts of ground ivy in conjunction with non-native shrub removal and native plantings. This work aims to restore the plant community present before the introduction of species such as Hedera L. The No Ivy League uses hand removal exclusively throughout Forest Park and other natural areas. Though chemical and mechanical removal can be effective in the appropriate situation the No Ivy League uses hand removal techniques to provide the experience of stewardship to a wider audience than other methods would allow.
Footnotes and Further Readings
- Girdle - The most basic technique to stop tree-climbing ivy dead in its tracks. Once you have located a tree infested with ivy, use either loppers or a pruning saw to cut through each vine clinging to the tree trunk at shoulder height and at ankle height. This severs the connection between the life sustaining roots and the rest of the ivy. Be sure to cut ALL vines as even one can continue to nourish ivy higher up the tree. Strip the Ivy away from the tree between the two cuts - some vines can be so big that you need to pry them away from the tree - just be careful not to damage the bark. Toss the stripped section of vine or save one or more as a trophy - how will your friends believe that you cut away a vine as big as your arm without the proof? Recheck the 'girdled' area for any thin vines which may have grown under the tree's bark and you're finished. But, after all that work, you don't want to give ivy a head start by leaving it to grow next to the base of the tree.
- Full Lifesaver - After girdling a tree, work to clear the surrounding area of ivy. Imagine a 6-foot radius circle around the tree you have girdled; begin by peeling back the ivy mat 6 feet from the tree and thoroughly pull every vine and root from the circle. You may also find it helpful to cut "slices" in the ivy mat within your imaginary circle and rip out ivy like a piece of pie. If you are working on a slope, pull downhill and let gravity work with you. Research has shown the once ivy has been pulled more than 6 feet away from a tree it will continue to grow away from the tree rather than towards it again in most cases. Our field tests have shown that a good 6+ foot Lifesaver will slow the re-infestation of a tree for over 5 years! The keys to an effective Lifesaver are consistency and patience; all vines and roots must be removed.
- Log Roll - This method is most effective in areas with a serious ivy problem, and when used properly can be quite efficient and gratifying. Begin by designating the area to be log rolled (a hillside or group of infested trees). Mark the top perimeter by cutting a line in the ivy mat, be sure to get every vine! If you are on a slope, cut horizontally across the slope to allow the ivy mat to be pulled downhill. Start to lift the mat and pull the cut edge of the vines downhill, rolling the ivy mat over itself. Let gravity do most of the work but also be aware of your surroundings unless you regularly perform backwards somersaults. Scan for native plants that may make rolling difficult and cut a line in the ivy perpendicular to your pulling edge so that the vine mat can be pulled around; this saves native plants that might otherwise have been uprooted by the thick mat and makes the log roll much more manageable. If you find yourself with a stuck roll, proceed to divide the log into several pieces and slice out the remaining perimeter. Once you have accumulated a few large ivy logs they must be mulched to ensure the ivy does not re-sprout - thoroughly chop, mince, and dice your logs and spread the mulch back over the area. While spreading mulch search for any small roots and vines they may have been left. Remember, it only takes one vine to reestablish the infestation.
Since 1994 the No Ivy League has worked tirelessly to remove English ivy from Portland's natural areas. Here are the numbers:
- Work Sites Visited - 118
- Total Site Visits Across All Sites - 1,803
- Workers and Volunteers Involved - 25,377
- Ivy Removal Work Hours Logged - 88,537
- Full Lifesavers Performed - 16,784 trees
- Lifesavers and Girdles Performed - 11,472 trees
- Square Feet of Ground Ivy Removed - 4,504,905
- Acres of Ground Ivy Removed - 103.42
Simply staggering! Thanks to all the folks who have joined us over the years - we hope that you will continue to come out and make a difference with us!
- Salem, Oregon No-Ivy League Chapter - Visit their website to view contact information for ivy commandos in Salem, OR.
- Do you have an organization you think should be on this list? Tell us about it, visit the Contact Us page.
- The Know Ivy League - Expand your horizons with peer-reviewed journal articles on a diversity of topics.
- Hedera helix: Effectiveness of Removal Protocol Adapted to Field Research Data - This poster makes the case for our Lifesaver method! Diligence and meticulous attention to vine and root removal really does slow ivy from climbing up trees again. Note:This was originally a very large poster; you may need to zoom in 50%-100% to read the text.
- Decennial Monitoring Report:1994-2004 and Appendices - Take a look at the No Ivy League's assessment of ivy removal throughout Forest Park during its first decade. An invaluable resource for those looking to get an inside look at the ivy problem, the report provides a starting point for a multitude of valuable research projects as well. Sit back and enjoy.
- The Dirty Thirty - Here is a great presentation aimed at educating you on 30 species of concern.
"What can I do about English ivy?"
The first step in halting the advance of our pernicious foe is education. Tell everyone you know exactly what ivy can do if left undisturbed; invite them to our Saturday work parties for a firsthand look and some awesome hands-on experiences.
Action is needed to truly make a difference. If you have ivy on your property, remove it or trim. Keep the ivy from maturing and spreading its seeds to the surrounding areas. Enjoy our Ivy Removal Instructional Video to get a better grasp on the techniques we use.
Works with property owners interested in habitat restoration, they also provide discounts at local nurseries for participants in their programs.
- Also check out the Columbia Land Trust certification program for backyard habitats.
- BES provides a wealth of information and services regarding watershed and habitat management. Learn more about the City of Portland's Invasive Species Program
- Providing up to $10,000 to schools, churches, businesses, and other community organizations for projects that connect people with watersheds and protect and enhance watershed health.
- The Cooperative Weed Management Area exists to create and support collaborative weed management among land managers and owners in and around the greater metropolitan area of Portland, Oregon.
- Many grant opportunities can be found through the WMSWCD, ranging from community projects to individual homeowners.
- A great resource for information about current invasive species threats around Oregon. The invasive species reporting hotline can be reached at 866-468-2337.
- A complete list of native plant nurseries (including seed, bare root, and potted distributors) in Oregon.
- The mission of the WRC is to inspire and support watershed stewardship at the neighborhood level in SW Portland. You can also contact Jen Seamans at email@example.com
Are you passionate about the English ivy problem and want to do something about it, but can't find the time to help with efforts towards ivy's eradication? Please help us by donating your hard-earned money to fund our hard-working Summer Youth Crews. They do the most hard-core, gritty ivy removal and are indispensable. Contact Us if you are interested.
An excellent use of English Ivy vines after removal, Urban Scout from the "rewild camp" program created this bike basket.