How deep can you notch a tree with out hurting it?

Notching a tree can stress it, so it's important to minimize damage. Generally, you should limit the notch to about one-quarter of the tree's circumference and only go as deep as necessary for your purpose, such as for carving or removing a branch. Avoid cutting into the cambium layer, as this is vital for the tree's nutrient transport. Always consider the tree species and its health before making any cuts.