Green Seattle Partnership has supported the cutting of 49,432 survival rings across the city. We would like to give a huge thank you to all our forest stewards and restoration crews who have dedicated their time to preserving Seattle’s historic forests!
The Issue
Common Ivy, also known as English Ivy, is a perennial evergreen plant brought to the US from Europe and is ubiquitous throughout Seattle’s urban forest. Left unmanaged, these plants grow into a dense mat on the forest floor and climb into existing established trees – preventing biodiversity and ecosystem balance while causing tree rot and other diseases. Eventually, ivy inhibits the tree’s ability to grow to its fullest potential and may even bring down a mature tree. Ivy can be extremely dangerous to trees during storms too as it can catch in high winds, making a tree more vulnerable to being blown over.
Ivy can also negatively impact forest grounds, as it can take over native species and over time can make it impossible for new trees or other native species to take root.
What is a Survival Ring?
Supporting an existing forest is easier than planting a totally new one and survival ring does just that. A survival ring is the cutting and removal of ivy from an existing tree at chest height down to a 5′ radius around the tree base. Ivy above chest height will decompose allowing the tree to continue its growth and remain part of the forest ecosystem. Ivy further than 5’ from the base of the tree can be continually removed manually.
Why It’s Important
Existing conifer trees play a huge role in the long-term health of Seattle Forests. Conifer trees are trees that are cone-bearing and can be found in many historic Seattle parks. An existing tree provides many ecosystem services including providing shade, structural habitat, improving soil quality, preventing erosion and allowing for deeper water penetration.
Many of the ecosystem services these trees provide interconnect with one another too. For instance, the deep shade conifers provide ‘shades out’ weed growth. Due to the dense canopy, direct sunlight doesn’t reach the ground and as needles from conifers fall, the needles create an acidic layer that isn’t favorable to common weeds. These existing trees have also been around for hundreds of years and created strong root systems that absorb most of the available water and nutrients.
During a Seattle Public Lands Habitat Survey conducted from 1999-2000, GSP created a classification guide to better understand the conditions of forests throughout the city after collecting data on various tree species, native plants, and invasive species in parks. Since many of Seattle’s forests are unique, this guide helps assess conditions at different sites to determine citywide forest conditions and defines park-specific restoration priorities. Parks are then placed on the Tree-iage scale depending on their tree composition and invasive species cover. For example, Seward Park and Discovery Park are classified as a 4 due to tree canopy and native species found at these sites.
The classification guide also ensures a healthy variety of tree and plant types. Without Tree-iage, forests over time would be susceptible to more dominating plants and trees that may not be the healthiest for that area. As work progresses within GSP to keep Seattle’s forests thriving, urban foresters also conduct a site-by-site analysis to assure that the species variety is fit for the location.
How to Cut a Survival Ring
Start by cutting vines at shoulder height, then again at the base of the tree. For thinner vines, use a pruner or clipper. For thicker vines, a small handsaw is recommended. Remove all ivy or clematis from the tree, from shoulder to base. Gently peel down and remove all vines from the tree, to minimize damage to the tree’s bark. Grub out the roots in a radius at least 5 feet away from the tree. Do not attempt to pull vines above shoulder height out of the tree. They will die and decompose on their own and pulling them down from high branches can possibly damage the tree.
You can also check out GSPs Invasive Species Removal Video to learn more about identifying and removing common invasive plants including ivy, laurel, and Himalayan blackberries.
Want to try your hand at cutting survival rings with Green Seattle Partnership? Check out volunteer opportunities in forested parks across Seattle!