THE ICE STORM OF JANUARY 1998
By Peter Grupe, Supervising Forester
Between January 5 - 9, 1998, more than 3 inches of rain fell incasing 4.5 million acres of northern New York State in 2 to 4 inches of ice. Cold surface temperatures and warm air aloft resulted in an icing event generally limited to lower elevations (below 1500 feet) and normally colder northeastern facing slopes (Kate Mountain, Norman Ridge).
Unlike man-made structures, trees do not have built in safety factors when it comes to withstanding stress. Most of their energies are devoted to competing for space, sunlight, and nutrients needed for growth and not in fortifying themselves to withstand above normal stresses. Since there was little wind associated with this storm, tree failures were due to vertical stress from dead weight rather than more common storm events where lateral and/or rotational stresses are applied. How individual trees fared was due in large part to crown architecture.
Conifers such as firs and spruces simply closed their canopy under the weight of the ice like an umbrella. Pines with more brittle and stiffer branches suffered both stem and limb breakages. Overall, conifers handled the weight of the ice much better than deciduous or hardwood trees.
The architecture of hardwoods is such that they offer a great amount of surface area for ice to accumulate. Trees with droopy crowns (birches, willows) and a lot of fine branches present a great amount of surface area. Limb failure, stem breakage and arching was very common.
Trees with upright branching characteristics (ash) presents the least amount of surface area to falling rain. Their upright branching directs falling rain toward the stem of the tree where it froze at a point where a tree is the strongest. Trees with this type of branching did the best.
Other trees have horizontal branching where the limbs meet the stem at a 90-degree angle (oak, sugar maple). Falling rain dripped from the branch quickly limiting the time it had to freeze. However, a little bit of ice on branches meeting perpendicularly with the trunk created such leverage that they were torn away. Heavy limb loss was common.
It needs to be said that in several areas around the Town of Franklin (Onchiota, Kate Mountain, Alder Brook), ice accumulation was so great that the trees were totally overwhelmed by the weight, snapping trunks and entirely stripping branches regardless of their crown architecture.
A tree's ability to recover from this storm is directly related to the extent of loss of live crown. Trees that have lost less than 50% of their live crown are expected to survive. Growth will be suppressed for a few years but will recover as crown is restored.
Many trees that have lost between 50 and 75 percent of their live crown will also recover. These tees will likely be impacted by various types of diseases leading to discoloration of the wood and increased rot. Growth suppression is likely for many years.
There is a very low probability that trees with greater than 75% loss of live crown will survive.
The most direct result from the loss of forest canopy will be the amount of direct sunlight that will now reach the forest floor. This will result in a flush of new growth. Trees that were struggling in the understory for sunlight will now be revived and will respond quickly. Thin barked trees such as; pine, birch and beech will most likely receive sun scald injury as bark warms from the sun. In time, the canopy will once again close and things will return to normal. The resulting forest will be similar in species composition; however the trees will be of lower quality due to disease. In addition, expect to find a large number of dead standing trees.
Town of Franklin
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