In right state of mind you can hear them.... you can even learn to communicate with them like a shaman.... but to gain that power you must love and respect them.. Peace..
"in the right state of mind"? I think its more your imagination, or too much weed or acid. Do I believe them to be sentient beings? maybe. Singing? doubtfully. Can we "talk" to them? really doubt it.
Yeah i don't know about the singing thing either, but i won't rule it out on possibilities. What i will rule out is that they "think " about singing. They don't have a brain so they can't think.
http://perdurabo10.tripod.com/id1161.html And also see book - Secret life of plants... they can communicate on big distances and many other fascinating things. They are not singing songs like people... they just sound sooooooooooo beautiful that it sounds better and more powerful than most beautiful human songs... That's music from other world, higher world.. It's not so hard to feel their emotions but to truly understand them like a shaman is not easy at all.
the proof of wind was given because the leaves of a tree or plant would move. what if the wind is the actual voice of the trees. a song... they humm.. that we breathe.
They get claustrophobic and when other trees grow to close to them they tell them to "FUCK OFF!!!!!!!!"