Volunteers at the Hakalau National Forrest Wildlife Refuse dedicate endless hours and days of their personal time to plant trees and plants. They may plant anywhere from 1,000 to 10,000 plants at a time. Often they will pay their own flying expenses from other islands just so they could be a part of the volunteer effort.
More can be read about what they do, and how you can participate in the 'OHelo Hakalau caches pages that are nearby
My hats off to you!