Bridge Grafting

Originally Posted by Wikipedia

A bridge graft is used to supply nutrients to the upper portions of a woody perennial when the bark, and therefore the conductive tissues, have been removed from part of the trunk. This wound is often caused by rabbits or other rodents, stripping the bark away and ring barking the tree. The inability of the plant to transport food manufactured in the leaves down to the root system, causes the root system to die and in the death cycle, the resulting lack of root system causes the upper portions of the plant to die. Where one-quarter or less of the trunk circumference has been ring barked, it may not be necessary to use this technique. It is also difficult on small caliper tree trunks. A bridge graft uses scions to 'bridge' the gap. Each scion is taper cut in order to accommodate the need for matching the cambium layers of the scion with those of the tree being repaired. Once in place the graft wounds must be completely seals to prevent moving of tissues which would disinhibit them from joining together ad to prevent dissection of the site which would lead to the death of the scions.