This is a reference to Terry Pratchett and his wonderful Discworld stories.
Now we all know how we establish how old a tree is by counting the rings of the tree truck. Well the Counting Pines came up with an idea to save them from being cut down. The notable feature of this remarkable tree it produced at eye height, numbers detailing the precise age. Its chain of thought that humans will no longer have to chop the tree down to count its rings, dimly aware that humans found a use for this, and within years they almost became extinct due to the house number-plate industry.