Harvesting Birch Bark
Does it harm or kill a birch tree when you harvest its bark?
If the bark is harvested properly it does not kill the tree. Does it harm the tree? Yes – to some extent – just like any injury. The tree has to switch gears and heal the injury and that takes some energy from other functions, so there is a cost.
Why does it not kill the tree?
Birch is one of a few tree species that has two very distinct and separable bark layers. This makes it possible to remove the outermost layer (the white one) and leave the inner layer (cork) intact. That inner layer protects the vascular cambium, which is the all-important layer of cells that produces wood to the inside and cork/bark to the outside. If the vascular cambium is exposed all the way around a tree (girdling) the tree dies, this is why it is so important to harvest correctly.
What happens after the bark is harvested?
The exposed cork layer turns from light tan to cinnamon, to nearly black. These are the black stripes around birch trees all too often seen along roadsides. (The Folk School tries to harvest the majority of our bark from trees that are being felled for land clearing or timber sales.) Over the next few years the black cork begins to crack into small rectangular shapes exposing new white bark behind the cracks. After 10 or more years the black rectangles begin to flake off exposing a different form of outer bark. It is white but carries with it the pattern left from the cracking of that black cork layer. At this time the bark can be harvested again.
Please remember:
- Trees are living beings and extremely important members of our community, treat them with respect.
- Learn how to sustainably harvest birch bark from an expert before you attempt to harvest bark yourself.
- Only harvest what you honestly intend to use and whenever possible harvest from trees slated to be cut down for other uses.
