The question I see is what do we define as language and communicating.
Do we mean that trees can relay information to each other, as well to other species? Sure, that makes sense.
For example, you could make a case that a large tree communicates with the saplings in the underbrush. By shading them, it is letting them know that it is the alpha individual in this area, convincing them not to grow.
We can also say that trees release chemicals that have an effect on surrounding life. This could also be called communication.
Finally, we could say that a loudly creaking tree is communicating to people around it that it is growing old, getting stress fractures, and could break off a branch that could pose a danger.
Any of the above could be considered communications.
To counter this, I could make a case that a truck tire can communicate just as effectively. It can cast a shadow which would prevent vegetation from growing. It could leach chemicals over time which would have an effect on the surrounding life. Finally, it could convey a threat by making loud bumping noises while it is bouncing towards you on a freeway.
Nature is interesting and complex. We continue to discover new and exciting things about how it works. I think anthropomorphising these effects makes them exciting, but does not necessarily add to how we understand them.