Deer are active and browsing in Missoula gardens every day of the year but fall is the time when they cause the greatest damage to trees. It’s not browsing but antler rubs on tree trunks which severely injure of even kill trees. The living part of the tree trunk is concentrated in the outside ring just under the bark. These are the linked cells that transport water and nutrients up from the roots (xylem) and deliver sugars and other nutrients down from the leaves to the roots (phloem). The interior wood consists of dead cells that used to perform these processes but were left behind as the trunk grew and expanded. Their purpose at this point is structural. This structural wood is made up of complex, incredibly strong carbon based molecules enabling trees to support themselves as they grow larger. This is an amazing system but one vulnerability is the fact the living outer portion is protected only by the bark. Young trees in particular often have thin bark and are less able to protect the water/nutrient highway that keeps trees alive and thriving. Trees do not heal is the same sense as we do. Living cells at the periphery of the injury don’t have the capability to simply grow over exposed wood (thus, tree wraps and tree paints don’t help). Instead they grow over the wound in folded fashion and, in time, essentially roll over the exposed wood bringing bark with them. Eventually, the damaged section is covered but the “included bark” makes the trunk weaker from a structural standpoint. This weakness often results in a break or split in the trunk at some point in the future. For the home gardener, the point is to protect the trunks of your trees at all times from transport to planting to maintenance (weed eaters have killed many trees). Antler rubbing in the fall is a major problem and protection through staking or wrapping is required so that trees can continue to do their jobs of providing shade, beauty, privacy, habitat and the multitude of other things that contribute to our quality of life.