You can see in the close up picture how well the new bark is closing the damaged area. The new tissue has created a rounded edge that will eventually close up the hold completely. Since it was a young tree the damage should be repaired very fast, maybe even by next year. The two sides will close up then new tissue will form on the outside of those pieces and merge together to create a seamless repair.
If the cambium layer (the cells that transport water through the tree) had been girdled (damaged all the way around the tree) things would not have turned out quite so well. The parts of the tree above the wound would be irrevocably dead. A new tree could grow from below the damage but it would be a long process to turn it into as great of a tree as this Yoshino was.
Preventing Future Deer Damage to Young Trees
The ultimate solution to dealing with deer is to prevent it from ever happening. That takes foresight on the part of the gardener but after losing a couple trees you’ll remember next fall! I began protecting my trees with a black hardware mesh that has been very effective.
I just cut enough of the plastic mesh to wrap the lower exposed trunk of the tree and tie the ends together with some twist ties. I leave the mesh loose with a 3-4 inch gap between the mesh and the trunk. I’ve not had an issue with deer damage again on a tree where I’ve put the black plastic hardware mesh.
This product looks amazing but I haven’t tried it yet. It’s a plastic wrap that will go around the trunk of your young trees to prevent deer from rubbing against it. If you do try it let me know how it works!