Strong wind, steady or in gusts can damage trees by breaking limbs, splitting trunks, or causing trees to lean or fall. Once the wind has subsided take a close look at the trees for damage.
Broken limbs are easy to detect especially when trees are dormant. Branches could still be attached to the tree or have fallen to the ground. Remove any damaged or broken part of the tree by making a smooth cut at another branch or at the trunk. Broken branches are often caused by branches bumping or rubbing into one another.
A split trunk or tree occurs where two or more branches are joined together at an angle of 45 degrees or less. This is the natural growing pattern of some trees such as willows but it is more often caused by a tree losing its center leader. Once the leader is gone, the top buds that are left will do their best to replace the leader resulting in two or more leaders growing upwards forming a weak union. Removing all but one of the branches when they are small will solve the problem. When all the branches are left intact, they will continue to grow getting larger and heavier. In a strong wind the branches will sway in different directions stressing their union often causing it to crack and split.
Saving the tree is dependent on the amount of damage. Small tears can be bolted together by an arborist but often part or all the tree will need to be removed.
When trees are planted, they should receive enough support to keep it upright but the supports should be loose enough that the tree will move with the wind. The movement encourages the tree to grow anchor roots which run on or just under the surface of the soil. Their job is to hold the tree upright while allowing the top to sway in the wind. As the tree grows so do the anchor roots. In a mature tree the anchor roots extend far past the dripline of the tree.
For the most part the anchor roots hold the tree upright but if one or more of the anchor roots have been compromised the tree will topple over. There are a number of reasons why the anchor roots break including but not limited to: a tree reaching the end of its life cycle, changing soil conditions and removal of other trees and shrubs.
As a tree starts to reach the end of its life cycle the wood within the tree begins to break down as do the roots. The weaker wood in the anchor roots is more likely to crack as the tree sways.
Changing soil conditions affect the roots ability to anchor the tree into place. In an extremely wet year the roots tend to have a harder time holding the tree in place. Disturbing the soil and roots through construction, cultivation or compaction can compromise the plants root structure.
Plants are connected underground by what is called the Wood Wide Web which is made up of mycorrhizal fungi networks. Remove or kill a tree or shrub and the network must reroute which in turn will weaken the remaining plants making them more susceptible to wind damage.
To check for a broken anchor root, walk around the base of the tree looking for a new bump or lump in the soil surface. The bump is caused by a broken root moving upwards. If left, eventually the tree will fall in the opposite direction of the bump.
It is worthwhile to examine the trees after a bad storm as a falling tree or limb can cause large amounts of damage.
Linda Tomlinson is a horticulturalist that lives near Rocky Mountain House. She can be reached at firstname.lastname@example.org