A few days ago, I noticed that most of the bark of my twenty foot Metasequoia glyptostroboides had been stripped off from the ground up to about 4′. Footprints in the freshly fallen snow indicate that it was likely deer. I live in the Scarborough Bluffs area, so it is not unusual to see wildlife in our neighbourhood, although we have never known deer to forage in our back yard.
To protect the tree from further damage, I immediately wrapped the trunk with garden mesh to about 5′, but I worry that the cambium has already suffered permanent damage. Will it heal? If so, what should I be doing to help it?
It sounds as though your dawn redwood (Metasequoia glyptostroboides) has suffered extensive bark damage. As you may know, the phloem (layer of tissues that transport the sugars produced during photosynthesis in the leaves to the rest of the tree, keeping it healthy and alive), lies just underneath the bark. Significant loss of the phloem layer is detrimental to the tree, is often irreversible and may be fatal, particularly if the entire ring of bark has been removed and the tree is girdled. Unfortunately, a dying tree does not necessarily display signs of decline right away and it may lead one to believe that it is still healthy.
As this is a serious and immediate health risk for your tree, my advice would be to seek the expert opinion of a certified arborist as soon as possible. An arborist will be able to assess your tree in person and determine the full extent of damage. He or she will also be able to give an accurate prognosis and inform you of any possible strategies, if any, to help save the tree. There is a specialized procedure called bridge grafting which is used for some trees that have been completely girdled, and involves grafting healthy tissue to the tree above and below damaged areas. However, its success depends on the type of tree and the extent of damage.
To find a certified arborist in your area, please consult the ISA Ontario website.