Christoph
The idea is really nice. I like the high-key approach and the sepia tone, and the OOF tree is fine too. But what this sort of subject really needs is a much stronger composition, one where the frame and all the elements within it are balanced and complementary. That is not quite the case in your shot.
If the subject is still there (and the light is right) I suggest going back and trying some variations on this. What you somehow have to achieve (and I am always trying, but often failing) is to pull off the definitive shot. That is, a picture where the viewer is persuaded that this is somehow the defining treatment of the subject. There, that's a nice easy objective, isn't it?
John