You can save a tree with damaged bark by first assessing the type of damage. Once you know the severity of the damage, you can implement a method to care for the wound.
Trees Can't Heal
According to the New Mexico State University (NMSU), trees are unable to heal. Instead, they seal wounds with a "callus" tissue. This sealant grows around the edges of the wound. The tree produces new wood to grow around the wound. This isolates and protects the wound from further exposure and damage.
Ragged Bark Hampers Sealing Process
You can help this process move faster by attending to the wound. Ragged bark from a wound can hamper even the healthiest tree in its attempt to recover. You can assist removing the ragged bark and dressing the wound. This is called bark tracing.
Bark Tracing Method
Remove the jagged bark around the wound and create a smooth rim to replace the uneven one. This uneven bark often continues to rip and cause further damage, so it's important to remove it.
- Sharp chisel
- Carefully cut away the jagged bark using the chisel and hammer.
- Discard any torn bark and remove any loose bark surrounding the wound.
- Forest Keepers warns not to chisel into the wound, just around the edges.
- The growth of new bark over the wound is a good indicator the tree will recover.
Repairing a Girdled Tree
If a ring of bark has been removed from the tree, the damaged tree has been girdled. This is a serious wound that can cause the tree to die. The risk depends on how severe the girdling is. Beavers are notorious for girdling trees.
Degrees of Girdled Damage
According to New NMSU, if the damage is more than 25 percent, it's difficult to save the tree, though not impossible.
- A patch of one-fourth the circumference of the tree won't kill the tree, but it can weaken the overall tree health.
- When the patch is 50 percent or more of the tree circumference, the tree will have a very difficult time surviving.
- NMSU warns removing the one band that encircles the tree will eventually kill the tree.
How a Damaged Girdle Affects a Tree
When this first layer (phloem) is exposed by the removal of bark, it sets off a chain reaction.
- The phloem transfers the nutrients from the photosynthesis process generated by the leaves.
- Without the protection of the bark, the phloem can no longer send that energy to the roots.
- If the roots don't receive this energy, it can no longer transmit water and minerals up the tree to the leaves.
- The upper part of the tree will begin to die while the roots feed off the nutrients it has stored.
Bridge Grafting Method
Since the tree roots are the last to die, a repair graft (bridge graft) can often save the tree. This graft literally creates a bridge of life between the roots and leaves. Depending on the success of the bridge graft, the tree can recover. The bridge buys enough time for the tree undertake the sealing of the wound and grow new tissues around it.
All you need is a knife and branches/twigs.
- Clean the tree wound with the bark tracing method. Remove all uneven and sharp edges by rounding them out. This includes removing any loose bark.
- Select healthy branches or if the tree is small, select healthy twigs.
- NMSU suggests the ideal branches/twigs should be no larger than the diameter of your thumb.
- Make sure the branches/twigs (bridges) are longer (one to three inches) than the wound width.
- Its phloem can only travel in one direction so it is important you mark the top of the bridges.
- Using a knife, trim one side of each of the branches (the end of the branch) until it can be flattened against the tree trunk.
- Then, trim the other side in order to create a wedge.
Create a Flap for Bridges
You need to create flaps in the tree bark to receive the bridges.
- Using the knife, cut two parallel lines beginning at the wound. Be careful to leave the flap ends attached to the tree.
- The branches must be carefully inserted underneath the flap so as not to dislodge the bark from the tree.
- Insert the branches (bridges) underneath the flap.
- You should end up with the flap still attached to the trunk.
- The goal is for the bridges and the phloem and cambium beneath the bark to grow together.
- The graft will then re-establish the exchange between the leaves and roots.
- While there's no guarantee the bridges will save the tree, this technique gives it a chance to recover from the damage.
- You know the bridges are working when the tree sprouts new leaves and the canopy grows back.
The simplest repair method is reattaching bark to the trunk. If the bark has been scaled from the tree, you can possibly reattach it.
- Fresh water
- Duct tape
- Clean the tree wound with water (nothing else).
- Gather the bark pieces and fit them back onto the tree. Check to be sure you place the bark, so it's growing in the right direction.
- Secure the bark with duct table wrapped around the tree trunk.
- Remove the tape within a year if it is still secure. If the bark has reattached itself to the tree, then it'll remain attached.
Things You Should Never Do
There are a few things you should never do when treating a tree wound since they will interfere with the tree's natural response to a wound.
- Never use a sealant.
- Never clean debris found inside a cavity wound.
- Never paint over the wound with tar, cement, or tree paint.
Saving a Tree With Damaged Bark
You may be able to save a typical tree with damaged bark if you react quickly. For severely damaged trees, you may need to consult with a tree specialist.