having an ISA membership means :

Benjamin Ormand, founder of Treescape Solutions is a member of the International Society of Arboriculture (ISA), the most prominent tree services organization in the world. Benjamin is on his way to gaining his arborist certification from this group, and has created a profile with the organization associating his business Treescape Solutions.  He is currently taking courses with this group and will attain his certification soon.  "Through research, technology, and education, the ISA promotes the professional practice of arboriculture and fosters a greater worldwide awareness of the benefits of trees."

Treescape Solutions, LLC BBB Business Review