Maybe they are a bit scared of the metal Treebeard coming to life overnight and herding up all the green trees of Moseley and leading them in a botanical march against their 4x4s?
Even my Dad likes Ents and has been known to say: "Ooh, that tree! It looks Entish!" And he wouldn't pick up a copy of Lord of the Rings if you paid him (the only bit of the films he liked were the parts with Ian McKellen, Sean Bean and Bernard Hill, and only then if they weren't being 'silly and far fetched').
Anyway. It might give people a genuine reason to visit Birmingham...