English Ivy is one of the most common and persistent invasive plant species in the Pacific Northwest. If you haven’t read last month’s post, Ivy Invaders, check it out! This year marked Portland Parks and Recreation’s 15th annual No Ivy Day, a citywide effort to eradicate invasive ivy from parks and natural areas and improve native habitat. This year, the Johnson Creek Watershed Council began hosting No Ivy Day at Indian Creek Natural Area, because previous years efforts were so successful that we graduated to a new site! Indian Creek is a small natural area in the Lents neighborhood of SE Portland.
On Saturday, October 27th, 35 volunteers joined us to remove invasive ivy! We were joined by Groups from Playworks AmeriCorps, La Salle High School, and Cleveland High School’s National Honor Society, along with neighbors. Together these volunteers, JCWC and Portland Parks & Recreation cleared thousands of square feet of invasive English ivy. We focused primarily on saving trees from climbing ivy. Strongly established ivy is full of water, and its combined weight can be heavier than the tree itself! If left untreated, this ivy will eventually kill native trees. This causes gaps in canopy cover, which reduces shade. In turn, this lack of shade can raise nearby stream temperatures, which is dangerous for salmon populations. In non-riparian areas, the sunny spots caused by ivy’s tree tipping can promote the invasion of other invasive species, while weakening soil and causing erosion. It is astounding how one species can cause such widespread changes in a landscape.
English Ivy in general is harmful to native habitat quality. It kills native plants, and its berries can be toxic to some native birds. While ivy’s roots provide shallow depth erosion control, native plants do a better job of stabilizing slopes. Similarly, while thick mats of ivy do provide habitat for salamanders, native plants provide better habitat for salamanders and other important species too! When removing ivy, it’s important to revegetate these bare areas with native plants that can provide ecosystem services like animal habitat and erosion control. That’s why, in areas where we remove ground ivy, we are bringing school groups to Indian Creek to plant native species in the coming months!
Our volunteers saved over 50 trees from ivy, and removed a large amount of trash from this natural area. And, our efforts were not alone. Across 16 other No Ivy Day sites, there were a total of 465 volunteers helping Portland Parks & Recreation and other great environmental organizations! Together, No Ivy Day Volunteers…
- Removed 83,000 sq. ft. of ivy. That is equivalent to 1.9 acres. WOW!
- Saved more than 200 trees from ivy
- Removed 3000 sq. ft. of other invasive plants
- Planted 375 plants
- Mulched 100 plants
Thank you everybody for your hard work! If you have English Ivy in your yard, please consider removing it! You can also educate your neighbors, and find volunteer events removing English Ivy and other invasive plants from natural areas and parks in your neighborhood.