Numbered trees

Why are all the trees on campus numbered? [3356C]

Duke serves as a tree prison, and prisoners are given numbers.  Also, it’s part of an inventory to help monitor the health of and schedule maintenance on the trees.  The round metal tags identify a sample (certainly not all) trees in different stages in their life cycle, of different species, etc., and if problems are noted then the grounds people can tackle the problem on other trees with similar characteristics.