I live near Sidney, British Columbia and for the last 42 years I have visited Orcas Island hundreds of times. Recently, I was alarmed to see English ivy beginning to invade the island. This very aggressive, invasive species has become a huge problem on Vancouver Island. In many parks and natural areas it has smothered out native species and is threatening urban trees. The weight of ivy can cause trees to topple in high winds. It also blocks out sunlight thus preventing photosynthesis so that the tree eventually dies.
Heavy infestations of ivy are very difficult to control, but you still have time to eliminate it in the San Juan Islands. To remove ivy from a tree it is only necessary to cut it at chest height and then pull to the ground. You can pull it back from the tree like rolling a carpet along the ground towards you. Without a root base, all the ivy above the cut will die. Ivy needs to be carefully disposed of because any left in the environment will readily root or seed.
Good luck with protecting your island trees and habitats from this aggressive invader.
Cordova Bay, British Columbia