I think it's a birch - I don't know any other tree with white bark. Normally they grow in groups. This one, being alone, was perhaps more prone to be shaped by winds.

The top photo - my trail was crossing a stream. Not a big deal in the summer but a bit of a challenge in November. So the owner of nearby field put this bridge across the stream. However, on the other side of the "bridge" there's a forest, I guess they didn't want to make it that easy for wild boards to come and help themselves to whatever was growing on the field.