Bark is like the “skin” of the tree. Just like how our skin protects our inner parts, the bark of a tree protects the layer known as the “phloem”. The phloem is the innermost living tissue of the tree, and it transports the sucrose made through photosynthesis to where it’s needed. Without bark, this sensitive tissue would be open to superficial damage, infections, and insects.
This means that when the bark is damaged, the “circulatory system” of the tree is open to damage as well. Trees have healing measures that can help them repair the tissue so that diseases do not harm the movement of nutrients throughout the tree. However, this healing does not help bark grow back, but humans can help tree wounds heal cleanly so that what replaces it is just as protective.
Can Bark Grow Back?
Though it functions like human skin, tree bark does not heal itself as our skin does, and a tree cannot go back and fix or replace damaged cells. It has to limit the damage by preventing it from
spreading to the rest of the tree. Because the tree cannot grow its bark back, it has to use other means of sealing and healing.
The tree reacts by isolating the wound and preventing bacterial and fungal infections from getting at the sensitive phloem. It will create chemical and physical barriers to confine the damage, creating what looks like a callus around the area. This is why a healed wound on a tree looks so obvious. While a tree has the mechanisms in place to treat a wound, it might look rather ugly when left to its own devices. A trained arborist can help it heal in a way that looks better and, in certain cases, save the life of the tree!
Can I Help The Tree Heal?
There’s a lot we can do to help trees heal properly. First, you should assess the damage, because the extent of it will determine what you can do. A tree can recover from a wound that is as large as 25% of the diameter. Bark removed from an area greater than this can be a disaster for the tree.
If you notice a wound, use a sharp knife to clean any jagged edges of it and get the bark flush against the exposed wood. Make sure the corners are rounded off and clean, and be careful to avoid
exposing more live tissue by removing too much healthy bark.
You can also protect a tree from lawn equipment by planting ground cover or spreading mulch around the trunk of the tree. This barrier keeps a lawnmower or other piece of equipment away from the tree’s trunk so that the blades do not accidentally remove the bark.
Call an arborist before doing anything further. Tactics that seem helpful, like dressing the wound, are not always necessary. They can hurt the tree even further by preventing natural wound isolation, encouraging the growth of fungi, and acting as a food source for insects. If the wound is over 25% of the diameter of the tree, it might need expert grafting. An arborist will be able to assess the damage and give you the best advice for helping your tree heal the area where the bark is missing!