if your talking about European buckthorn, one of the best ways to recognize it is that the leaves stay on an green for a very long time, they also small dark berries.
European buckthorn is such a problem in minnesota and elsewhere but i hardly ever see 'em that large, maybe our buckthorn forests just aren't as mature yet. The problem with european buckthorn is that it is very hardy and spreads very easily as birds eat the berries that "pass right through them" and spread them everywhere.
A few years ago I contacted a park district where i live and asked if i could cut some buckthorn, and even offered to treat the stumps my self, as i guess you are supposed to treat them or they crop up a bunch of feeders. Anyway the district said they can't allow me to do that, for one reason or another, imagine that, someone is offering to remove noxious trees, and treat the stumps free of charge, and they say no, that's what i get for asking
