Celebrate Earth Day all week by volunteering at Portland’s living museum of trees! With 189-acres and more than 6,000 trees along 12 miles of trails, volunteers are incredibly important to maintaining Hoyt Arboretum’s tree collection and trail system, and it’s a unique opportunity for volunteers to learn about and care for rare and unusual trees and plants from around the world. This event is coordinated by Hoyt Arboretum, and registration is required through their website.