Enclose trunk far enough from bark to allow trunk diameter to expand as tree matures, and at least two feet higher than expected snow line. To protect against mice and voles push mesh two inches into the ground. Ellen, Sorry, There is no such thing as artificial bark. Once its gone so is your tree. Professional nurserymen protect their stock with a flexible tube that is placed around the trunk of young trees until they reach a good size.
Most retail nurseries sell tubes or can help find a source.
Tree wrap may also be used. Check with your supplier. Often they will replace a tree if it does not leaf out in the spring after a fall planting. Gobs of suppliers are on the internet. Argonne National Laboratory, Division of Educational Programs, Harold Myron, Ph.D., Division Director.