I would weigh in on the side of wrapping a young, newly planted, or thin-barked tree for the first few winters.  The Colorado State Forest Service suggests wrapping the trunk of thin-barked trees like honey locust, maple and linden because of drastic winter temperature fluctuations that can cause "sun scald." Young trees, newly planted trees, and thin-barked trees (cherry, crabapple, honey locust, linden, maple, mountain ash, plum) are susceptible to sun scald in the winter.

Sun scald is really an incorrect term as the sun doesn’t actually ‘scald’ the trunk or bark of the tree. Scald shows up on the west or southwest side of the bark in the spring following the winter months. On cold winter days, the sun can heat up bark to the point that cellular activity is stimulated. The bark temperature drops at night, killing the active cellular tissue.

Older, more established trees are less subject to sun scald because the thicker bark can insulate dormant tissue from the sun's heat ensuring the tissue will remain dormant and cold hardy. Sun scald can be prevented by wrapping the trunk with a commercial tree wrap, burlap, plastic tree guards, or any other light-colored material, up to the first branch. The wrap will reflect the sun and keep the bark at a more constant temperature.

Put the wrap on in the fall and remove it in approximately April or after the last frost. Newly planted trees should be wrapped for at least two winters and thin-barked species up to five winters or more. .

Other important winter tree care includes:

1) Mulching the tree with 2 to 4 inches of wood chips, bark, leaves, or other organic mulch near the base of the tree, but not touching the trunk.  Mulch reduces soil evaporation, improves water absorption and insulates against temperature extremes.
2) Watering in the area extending from the trunk to the extent of the longest branches. Water slowly, with a sprinkler or soaker hose, at the rate of 10 gallons per inch of tree diameter. During extended dry periods in the winter (more than two weeks without snow cover), water on warmer days, when snow has melted off and the temperature is above 40 degrees.

Best of luck with your new trees,