Trees are a source of solace for lots of landscape photographers. The symbolism is obvious, and the clarity and sense of peace obtained by taking a walk through woodland, even without a camera, is something most people can relate to.
There is a danger of photographing trees being perceived as cliche, but I could never accept that, any more than I could accept human portraiture as cliche. Every portrait has the potential to be unique, and so with images of trees. It just depends how much of yourself you are willing to add.