Forest restoration in the Puget Sound area starts with the removal of Ivy. It is easy to identify, relatively easy to control, and constitutes the biggest threat to forests.
With respect to invasive plants, I think there is a consensus, that the single most important thing that people can do to help the forests of the Puget Sound region, is to keep Ivy from growing up trees. You may have seen vacant parcels of land in which curtains of Ivy hang from the skeletons of dead trees and bury all the other shrubs and plants in deep masses of vines. However, I have learned, that without too much work, Ivy can be effectively removed and controlled. In some ways, I think it is one of the easier of the invasive weeds to control.