Counting trees

Recently it's dawned on me that every mature tree in Edinburgh city parks now sports a little blue tag with a number on it. The younger trees are free from this branding, presumably because as they grow and expand the tag might well ping off. One wonders quite why so much effort has gone into tagging each tree. Perhaps if one escapes it can be brought back to the right place. I should ask the City Council. Maybe there's a job opportunity there - I would exchange my day job for one counting trees.