Decaying or dead branches are already weakened and have a high probability of breaking when loaded with ice. The surface area of lateral branches increases as the number of branches and the broadness of the crown increase. Contrary to popular belief, the wood strength of sound branches matters less than the ability of a tree to withstand breakage at branch junctures and the presence of fine branching or a broad crown that enhances ice accumulation. Examples include Siberian elm, American elm, hackberry, green ash, and honey locust. Trees with imbalanced crowns are also more susceptible to ice damage.
Many conifers have an excurrent branching pattern, and many resist ice storm damage.
Some tree species, such as sweet gum, have an excurrent growth habit when young but develop a decurrent growth habit later in life. These species are more resistant to breakage when young than broadleaf trees that do not exhibit a juvenile excurrent branching pattern. Some trees species that typically exhibit a decurrent branching pattern have clones with an excurrent form, which should have greater resistance to ice storm damage. Tree species with strong branch attachments have greater resistance to breakage than those with included bark. Forest understory tree species such as ironwood and blue beech and trees that mature at small heights, such as amur maple, are also relatively resistant to ice storm damage.