Watershed & Environment

Invasive Ivy

English ivy

On a very hot evening in June 2019, Arnold Creek neighbors met at the Open Space belonging to the Oak Creek subdivision. Erik Horngren from the Watershed Resource Center shared a very thorough background on Ivy; why it is such a huge problem and how to deal with it. He then demonstrated cutting it off trees and the fourteen enthusiastic attendees grabbed the tools that Erik provided and practiced their Ivy removal techniques.

Ecological Threat (from invasiveplants.org)
English ivy is an aggressive invader that threatens all vegetation levels of forested and open areas, growing along the ground as well as into the forest canopy. Vines climbing up tree trunks spread out and envelop branches and twigs, blocking sunlight from reaching the host tree’s foliage, thereby impeding photosynthesis. An infested tree will exhibit decline for several to many years before it dies. The added weight of vines also makes trees susceptible to blowing over during storms. English ivy has been confirmed as a reservoir for bacterial leaf scorch (Xylella fastidiosa), a harmful plant pathogen that affects a wide variety of native and ornamental trees such as elms, oaks and maples.

 


Lesser Celandine

Lesser celadine with yellow flowers

Invasive lesser celandine can easily out-compete spring-flowering plant communities and negatively impact local wildlife.

More: Lesser Celandine (pdf document at 4countycwma.org)

 


Weeding Wars in Arnold Creek
Tackling Invasive Species in our Watershed

An engaged group of neighbors attended our October 2018 meeting to welcome a distinguished panel of neighborhood weeders talking about which plants they target and why and how they do it. Michelle Delepine from West Multnomah Soil and Water Conservation District provided information about services offered to residents dealing with Early Detection and Rapid Response (EDRR) noxious weeds on their property. There were fresh live noxious weed specimens from our neighborhood and we also enjoyed show and tell of favorite weeding tools. There are many free resources for residents wanting to eliminate noxious weeds from their property:

Brochures on the four plants we focused on at the meeting:

  1. Lesser Celandine (pdf document at 4countycwma.org)
  2. Garlic Mustard (pdf document at 4countycwma.org) 
  3. Japanese Knotweed (pdf document at invasive.org)
  4. English Ivy (pdf document at 4countycwma.org)

More resources mentioned at the meeting:

Southwest Watershed Resource Center

Located in the Southwest Neighborhoods office at the Multnomah Arts Center. Inspires awareness and action on behalf of watershed health in SW Portland. Funded by City of Portland Bureau of Environmental Services.

Tryon Creek Watershed Council

  • Assistance with applying for restoration project grants
  • Management of restoration projects for individual or adjacent landowners in the Tryon Creek watershed. This often includes treatment of noxious weeds and free native plants suitable for the site.
  • Watershed 101 workshops for neighborhood associations that includes education and hands-on work party.

Backyard Habitat

West Multnomah Soil & Water Conservation District