Winter conditions severely affect trees that are already stressed, so one key to preventing winter damage is keeping your trees in good health year-round.
Protection from the elements
In winter, the ground root system of a plant or tree will freeze, stopping or slowing water circulation. Evergreens are at a greater risk than other trees, because they hold their needles in the winter -- the needles lose moisture to the atmosphere as well as to the plant itself. Because trees are not able to replenish lost moisture, leaves can dry out and fall off. To minimize the effects of winter drying, high-value evergreens can be treated with wax-like anti-desiccant substances that hold moisture in the leaves.
Snow and ice can become very heavy and break branches or even topple an entire tree. Pruning your tree can make it better able to withstand the extra weight of ice and snow. Mulch, too, produces a year-round benefit because it increases microbial activity and fertility of the soil underneath the tree. Mulch has the added benefit of acting as insulation between the root system and the above-ground temperature, which helps retain moisture in the root system and limits the fluctuation of soil temperature. Ensure that the ground is not frozen and has enough moisture before you add the mulch, and make sure that no more than 2 to 4 inches of an organic matter, such as wood chips, is used.
How road salt can be harmful
Salt used for de-icing streets and sidewalks is harmful to trees, shrubs, and grass. You can avoid damage by using only noninjurious types of de-icing salts or avoiding salt applications to sensitive areas. Some specialists feel that you can reduce salt damage by flushing the soil in treated areas with large amounts of water in the spring.
The severe ice storm of 1998 resulted in damage to many trees in eastern Canada and the northeastern United States. Ice storms are common in the region, so most trees are remarkably resilient. Trees that did not suffered major structural damage, such as split trunks, will recover over time. Trees are dormant in the winter, and damage at this time of year is less serious than if it occurs during the growing season. If a tree is reasonably healthy and only a moderate number of branches are damaged or removed, the tree should recover and in a few years will appear normal.
Page 1 of 2 -- How to encourage your trees to bounce back from winter, plus important safety tips to keep in mind when tending to your trees this season on page 2
