Trees in themselves aren't so bad. It's when you get into the woods that the problems start to appear.
Woods are r-e-a-l-l-y untidy! There's lots going on to distract the eye.
There's usually a heap of dynamic range to deal with, with all those bits of light poking through the shadows.
In woodland, I generally prefer to look for interesting parts of a tree rather than trying to get the whole thing in, unless the topography allows a view that excludes the sky.
Fog helps...a lot!