Just some input-
I happen to have a fairly large grove of redwood trees in my back yard. I built quite an extensive system of walkways and a tree house so that my friends and I could wittle away the summer hours. I spent many a nights in those trees and I have to say that I would always awaken a lot more refreshed and alert than any time on the ground. Could this be the Mystical Arbor Day Ki we are debating now?
Quite a few years back I invested in a Japanese Maple Bonzai. I keep it in my room and it does bring sense of calm and togetherness to its surroundings.
I'm no expert at all but doesn't Feng Shui (the bringing of positive Chi to a household through room arrangement) have a practice of keeping plants in the room to welcome good Chi? In any case I could be convinced that plants are a good source of Ki. (Possibley because of their direct rooting to the earth?)
Just a few thoughts-