Here are some organizations that people with interest in trees, tree care professionals, and recreational tree climbers will find useful.
International Society of Arboriculture (ISA)
The ISA is the largest professional organization for the tree care industry, and the certifying organization for professional arborists. Here you can find the ISA-certified arborists nearest you as well as lots of valuable information about trees and tree care.
Tree Climbers International (TCI)
Founded by Peter Treeman Jenkins in 1983, TCI is dedicated to the activity of recreational tree climbing for kids from 5 to 90 years old. TCI-certified instructors lead classes and courses for beginners and experienced climbers, climbing events, overnight treetop camping, birthday parties, and expeditions around the world to climb unique trees.
This organization is dedicated to conserving and planting trees in the metropolitan environment. It is responsible for planting thousands of mature trees in Atlanta. Find links here to tree ordinances that might affect you, the names and phone numbers of municipal arborists that have jurisdiction in your area, and a lot more information about trees.
This is the state agency that manages and protects Georgias forests. Find an abundance of information about forestry-related programs as well as a list of Georgia certified arborists and foresters here.