bear scratches on tree trunk

This dead tree had fairly deep scratches four to six feet off the ground. I have never seen a bear in the area, but have seen lots of bear droppings and other signs of bear activity. This was about 20 miles from the creek where I found fresh bear tracks in early September (http://www.projectnoah.org/spottings/7294430), but in both cases I'm guessing the animals were black bears.