Arbor Month 2021

Celebrate with us this April!

April is Arbor Month, and we will be celebrating trees and our urban forest all month long!

Lake Oswego has a diverse urban forest and has been a member of Tree City USA for over 30 years! This means that individual trees throughout the city connect to create an urban forest system that provides countless benefits to the community.

Do you love Lake Oswego’s trees and want to make a difference? Oswego Lake Watershed Council (OLWC) is encouraging the community to celebrate Arbor Month 2021 by working together to preserve our urban forest.

Be a Tree Hero!

invasive ivy

All April

In April OLWC is encouraging community members to make a difference by removing tree ivy in their neighborhood. Being an “urban forest superhero” is hard work and we want to ensure that we recognize the efforts of our community super heroes (sorry, no keys to the city will be rewarded).


iTree Training Sessions

iTree Tree Inventory Community Science Program

April 10 and 14

Lake Oswego’s urban forest is comprised of thousands of trees, so OLWC is relying on our passionate volunteer community scientists (like you!) to make this project a success!

Two  online training sessions were conducted on April 10 and 14.  If you missed these opportunities, let Jack ( know so he can alert you when the next sessions are scheduled.


    Thank you, Tree Heroes!

    What can you do to it mean to be an urban forest hero? Community members can make a huge difference by removing tree ivy in their neighborhood! OLWC works with individuals and community groups to steward our urban forest and improve tree heath through invasive species removal.

    In April 2021 we celebrated Arbor Month with a variety of ivy pulling initiatives and events. We had participation from at home volunteers, students, and community organizations. In April we collectively saved over 200 of Lake Oswego’s trees from invasive ivy vines! Special thanks to Lake Grove Urban Forest Committee, Lake Oswego High School, and Lakeridge Green Team for being LO Tree Heroes and organizing neighborhood and on-campus events.

    If you are ever out removing ivy, take a photo of trees that you saved from ivy and send them our way by tagging @oswegolakewc on social media (Facebook, Instagram) and using #LOTreeHero . If you live outside of Lake Oswego, you can still participate by using #treehero .

    Information on how to safely remove ivy can be found below. If you have additional questions about ivy removal methods or how removing ivy can benefit our trees, please email Jack Halsey, Watershed Coordinator.

    Volunteers clearing ivy from trees
    Volunteer crosses creek to remove invasive species
    Students pose for a photo after a volunteer event
    Why are we removing ivy?
    Atlantic Ivy (Hedera hibernica) and English ivy (Hedera helix) are plant species native to Eurasia, Northern Africa, and Macaronesia. Ivy can be easily identified by its distinct waxy evergreen leaves. Ivy was introduced to the Pacific Northwest as an ornamental plant valued for its rapid growth and aesthetic value. Over time, Ivy has escaped cultivation and spread throughout our forests, natural areas, and backyards. Ivy can rapidly invade natural areas, outcompeting and suppressing native plants, and thus altering ecosystem functionality. Of particular concern is Tree Ivy – ivy that climbs trees to access more light.

    Ivy’s biggest advantage is its ability to climb trees. By using existing tree trucks for structure, Ivy can rapidly grow up trees to access light without expending energy on creating its own support structure. The problem? Ivy takes sun and water resources from trees. And, it’s heavy. If left unmanaged, mature tree ivy can break limbs and eventually topple large trees. By removing ivy, we can save our trees! If you’re interested in the science of ivy’s success, check out this great article

    Where can I remove Ivy?
    Only remove ivy if you have permission from the landowner! If you own land and know where your property lines, then you are ready to remove ivy! If you are a renter, contact your landlord to obtain permission to remove ivy from the property. If you want to remove ivy from commonly owned property, property owned by businesses, parks, schools, or natural areas, you must obtain permission from the landowner. Email if you need help determining land ownership or contacting a land manager.
    What tools do I need to remove Tree Ivy?
    • Work Gloves
    • Hand Clippers or Loppers
    • Pruning Saw (for large ivy vines)
    • A camera (optional). Take before and after photos and share your work on social media using the hashtag #LOTreeHero

    If you don’t have these tools, ask a neighbor if you can borrow theirs! Or, contact and we can lend you tools.

    How Do I Remove Ivy?


    “GIRDLE: The most basic technique to stop tree-climbing ivy dead in its tracks.

    Once you have located a tree 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 the ivy from a tree, work to clear the surrounding ground ivy

    Imagine a 6-foot radius circle around the target tree, begin by peeling back the ivy mat 6 feet from the tree and thoroughly pulling every vine and root from the circle.

    You may also find it helpful to cut “lines” in the ivy mat within your imaginary circle and rip out ivy like a piece of pie. Cutting “lines” in the dense mat allows for precision removal around delicate plants and immovable obstacles. You will save more time and energy pulling around rather than through these obstacles. If you are working on a slope, pull downhill and let gravity work with you and  The keys to an effective Lifesaver are consistency and patience; all vines and roots must be removed.”

    Ivy removal methods in this article are from No Ivy League’s extensive website on Ivy removal. Want to learn more about invasive ivy removal? Check out their website:

    Now that you’re an ivy removal expert, you can go out and remove ivy! Be sure to only remove ivy on property that you own, or if you have explicit permission to remove ivy there! Take before and after photos, and share your progress on social media. Include the hashtag #LOTreeHero so we can see your work. There is a lot of tree ivy out there, and no hero can protect the entire urban forest alone- encourage your friends and neighbors to be urban forest heros by removing ivy on their trees, too! If you don’t have social media, you can email your photos to and we will share the photos for you. Thank you so much for stewarding our urban forest!

    Want to do more stewardship work in Lake Oswego? Check out our event page and sign up for an upcoming volunteer event!