See below and scroll through for some lovely photos of trees by James Balog:
Also for some eyewatering tree photos see National Geographic's lot here:
The October 2009 NG issue had a stitched photo of 84 images of a 1,500 year old Redwood, 300 foot high with climbers in the photo for perspective. Best stitched photo of a tree ever. Photo was by Michael Nichols.
There was also a tv programme about the making of the photo too. short video here: