It depends on the kind of dependency trees. I've seen plenty of semantic-y dependency trees and plenty of syntactic-y dependency trees. I'm not sure how common either really are ever, but on the semantics side, it's the best you get, usually, and isn't all that good for semantics. It's fine for syntax, more or less.

I think that if you say: dependency treebank, most computational linguists will expect syntactic dependencies. I agree that the notion is blurred sometimes, e.g. by including word senses or preferring semantic attachments in some cases over semantic attachment. There may also be treebanks of the semantic-y kind, but I haven't seen or used them often.