If you write with a POV character (e.g. first or third person POV) your descriptions should always be colored by what that character is thinking and feeling.
For example, if the character is driving her car through a neighborhood and this is where she grew up and she knows everyone and has memories from many parts of the place, the description will be of one type.
If, on the other hand, the character is driving her car through a neighborhood looking for her underage daughter who ran away to a shady boyfriend, the description will be different.
In your example of the forest, if you have a POV character, let them think (or note) the trees have thick nice branches a person could hang themselves from.
I like oaks. They have these strong, reliable branches. If you hung yourself from one of them, they wouldn't fail you.
It will definitely be characterization and description in one, which is the whole purpose of "coloring" descriptions by the mood and personality of the POV character. We tell a little about what's being described and a little about the person seeing it.