Prepare Your Trees for a Storm
- Many trees’ root systems were weakened by the drought and high winds hit under very wet conditions.
Currently, some tree root systems have rot in them due to the high soil moisture we had in and the dry conditions we’ve had again the last few years.
Things that increase a tree’s chances of storm damage:
- Trees on lots of homes that have been built in the last five years or so. Many of these trees will have root damage from lot clearing and home construction.
- Newly cleared areas with scattered trees remaining. The trees have not adjusted to the newly open grown conditions and higher winds. (new road construction)
- Areas with loose, gravelly soil.
Characteristics that increase a tree’s susceptibility to storm damage:
- Included bark where large stems meet.
- Rot in the roots, stem or branches
- Lopsided tree tops (previous storm damage)
- Trees with numerous small branches and twigs that create a sail effect (topping/poor pruning often causes this). Never top trees!
- Mechanical damage and poor maintenance (soil compaction, damaged tree)
Homeowners should examine their trees before the storm:
- Remove trees with large cracks or splits or severe root damage
- Remove tree branches with rot in them
- Advise power company of trees with branches interfering with power lines
- Contact a competent, certified arborist
- Good branch angles are 10 o’clock and 2 o’clock, closer together causes weaker branches
- Remove rubbing and broken branches
- Prune properly (do not flush cut to stem, but do not leave big stubs that will rot either)
Some trees have more brittle wood.
Some trees that do not have as many storm-related problems.
Prevention Measures that can make trees stronger and more resistant to storm damage:
- Prune to encourage good branch angles.Narrow branch angles are weak. They are weak because neither has sufficient space to add wood needed for strength.This can be prevented by removing one branch when it is young. The strongest angle is 10 o’clock and 2 o’clock.
- Encourage strong branch/trunk size relationships. Ideally lateral branches should be no more than 1/2 to 3/4 the diameter of the trunk. Branches larger than that often cannot be supported.
- Eliminate lopsided crowns and maintain a stable centre of gravity. Reposition a tree’s centre of gravity by selectively removing branches on the leaning side and encouraging branches on the opposite sided.
- Remove rubbing branches, suckers, waterspouts and temporary branches. Branches that rub make wounds and allow decay. One of the branches should be removed. Suckers and sprouts are rapidly growing and weakly attached. They often use more energy than they produce. Temporary branches low on a tree when it is young and protect young base from injury by the sun. After a tree is 3-4 years old, these should be removed. Never remove more than 1/3 of a tree’s leafy crown when pruning. Remove problem branches before they are 5cm in diameter when possible
- Don’t cut branches back to stubs. People often think long branches will break, so they shorten them. When a branch is left with a stub end, the new branches are weakly attached at that point.
There are six main types of storm damage:
Blow over
Tree is pushed over by high winds. Trees cannot adjust to the strong winds or cyclones. Past tree abuse, poor maintenance, pest and root problems make trees more susceptible.
Stem failure
Trees do not heal wounds. Trees grow over them and seal them off. Therefore, trees carry in its wood every injury they have ever had. These injured sites have weaker wood and can fail during wind loading and release. In trees with very large crowns, abrupt winds followed by a release can allow the tree to break by the inertia moving the tree back when it is released.
Crown twist
Trees with lopsided crowns (more branches on one side) cause the trunk to twist in wind loads. The tree can adjust over time with new wood, but old injuries will be magnified and failure can result.
Root failure
Fine absorbing roots and woody structural roots. Stress is put on roots from construction, disease, etc., and can snap or be pulled up.
Branch failure
Ice storms or rare downbursts leave branches unprepared and they can snap or tear downward. Included bark can also weaken the connection.
