I've done some Taoist meditation/Chi-Kung with trees. It's a very common practice. First we start off standing in front of the tree at about arms length. Next you perform the larger orbit meditation. Breathing in energy down your front centerline, through the perineum down your legs to your feet. Breathing out imagining the energy up you legs back through the perineum, up you spine over you head and out your nose. After you are conformable with that during the in breath do not stop at you feet. Imagine the energy going through the ground towards the tree into the roots up to the top of the tree (Expanding out to every branch and leaf.) On the out breath going back down the tree back out the roots back into your feet etc... You should imagine a continuos circuit between you and the tree. (Sorry for the bad explanation it's easier to show then write.)
You could also sit with your back against the tree. Feeling the energy of the shooting up the tree and penetrating into the ground. You then imagine your own energy doing the same. Here you are trying to be in resonance with the tree. Emulating its energy pattern, merging and sinking into the tree, becoming the tree.
In Ninja spiritual mysticism they do similar exercises with boulders, lakes, and even walls. The idea being that if you can resonate with the energy you are standing against it would be more difficult for sentries and pursuers to detect you.
P.S. Bruce thanks for keeping these forums interesting. I usually agree with the spirit of what you are trying to say and impart.