It may sound crazy but yes, you can eat bark! The inner bark of a white pine is edible and is packed with protein, carbs, and calories.
There are three layers of bark on a white pine. The outer bark is the brown visible to the eye; then there is a green layer followed by a white layer. You want to shave off the first two layers and harvest the white bark.
The raw bark can be chewed like gum, or you can roast it like a chip. It also makes a great tea if you steep it in hot water.
Between acorns and pine bark you can have a good amount of carbs in your diet which is the hardest thing to find in a survival situation.
Acorns covered on in this post.