Naturally Trees - Expert Arborcultural Planning, Advice and Care Since 1998

Storm Damage Prevention

by Andrew Scales | October 18, 2010

We have all seen evidence of what storms can do to our trees so now is the time to prepare your trees for the windy months ahead.

Hundreds of thousands of trees in Australia are storm damaged by wind, heavy rain and lightning each year. Estimates of property value loss from tree storm damage can exceed millions of dollars annually depending on how severe the weather is.

There are a few simple ways to help you quickly understand and prevent costly storm damage to trees. There are no real "cures" here outside of proper planting, prevention measures, management and treatment.

Trees biologically adapt themselves to wind and rain if these destructive agents are part of an average annual growing season. Under normal weather conditions, trees sway in the wind and it is this movement that strengthens the woody material to develop on the stem.

It is the abnormal weather conditions and storms that damage trees. There is just no way to protect all trees from all types of storm damage. Trees simply are not adapted to survive worst-case storms.

Storm damage to trees usually comes the following ways - via complete tree failure, stem/trunk failure, crown twist, root failure, branch failure and lightning strike. Total tree collapse, crown twist and lightning strike are considered catastrophic tree events that need immediate and proper attention.  Root failure, branch failure and stem failure are more subtle and can take years to kill the tree.

Catastrophic tree failure and damage is not only dangerous but can cause significant property loss and will be expensive to remove. Here are some ways to minimise storm damage:                                                                              

Complete tree failure:

With blowdown, the tree is pushed over and damaged by high winds. Generally complete tree failure occurs when the soil becomes too wet and the soil slips.  There is very little you can do to storm proof or protect a tree from hurricanes, down-drafts or tornado winds however avoiding root or ground disturbance will reduce th potential for failure. 

The "Cure":  Keep trees healthy with timely watering and mulching. A strong, healthy and undisturbed root system will provide the best support to a tree during these events.

Canopy twist and branch failure:

Tree canopies are similar to sails on a yacht. Excess canopy will increase wind loading and place significant stress on trunks and branches.  More wind on one side of the crown than on another produces a twist on branches and the main stem.  Stem twisting will magnify weaknesses around old injuries and the stem will split or branches collapse. Past tree abuse, old wounds, poor maintenance and pest problems all predispose the tree to storm damage by weakening the supporting wood.

The "Cure":  Eliminate severely lopsided crowns and thin canopies to redue wind loading. Prune branches to produce a reasonably symmetrical crown.  Healthy, vigorous trees adjust more quickly to changes in the environment, are more wind tolerant. Remove or treat pest problems.

Root failure:

Tree roots support trees, store energy reserves and absorb water and elements that are essential to life. If roots become stressed or damaged, an irreversible condition occurs leading to normal defence boundaries within the roots not functioning or forming giving way to pathogen intrusion into the tree. Damaged roots can go unnoticed for up to 7years before a tree will begin to show signs of stress.

The "Cure":  Keep trees healthy. A strong, healthy and undisturbed root system will provide the best support to a tree during these events.

Lightning Strike:

Lightning either moves in a narrow line down the branches, stems and roots or along the entire tree bole. Lightning directly destroys tree tissues by electrical disruption and heat all the way down the stem and there can be massive root damage. Damage caused by lightning leads to extensive water loss. Pests quickly attack lightning damaged trees.

Unfortunately, lightning strike is fairly common, most trees just can't be easily protected and have to be removed.