When you let go of the knot while descending, you automatically stop. We're describing the double-rope technique. One disadvantage of climbing with a double-rope technique is that damage to a tree may result from the rope moving across the live wood. Some trees with tough bark will resist the wear of the rope. Other trees are thin skinned and they will receive damage on the first climb.
Examples are sycamore, beech and maple.
There are techniques and tools that can be used to protect bark surfaces. They all serve to prevent the rope from coming into contact with the bark surface. Be aware of your climbing techniques and avoid hurting the tree. Different methods are used to climb. The most common method uses mechanical ascenders.