I agree with your sentiment (that headlines containing question marks are generally conjecture and not news), but in this case the answer pretty clearly is "yes, trees do communicate." To be sure, it's not a great headline, but it was chosen by the original author so maybe you should post a comment on his blog if you're concerned.
Sorry, I don't see any examples in the article where trees communicate, just that they tap into each other's resources. Was there more to it than that?
If not, that's a pretty misleading headline. When I water a plant, it's not communicating with the garden hose.
That depends on how you define 'communicating'. It's all essentially about definitions and opinions. This is probably a tad too cynical, but to me it seems most every discussion boils down to these two things. We'd really need a better framework for discussing these things, I think we'd waste a lot less time arguing over semantics. A beautiful example is the discussion whether God exists or not. If you could just force both participants to define what God is, then the discussion over his existence would be over in seconds. (with the conclusion that there is no way of knowing, so let's stop talking about it)
