Reducing Tree Wind Damage
The 2011 wind storms storms in Southern California caused unprecedented damage to our structures, utilities, and landscapes. Assessing why certain trees were damaged while others survived is a worthwhile endeavor; not only to protect the aesthetics of the trees, but also the property around them.
Numerous studies indicate proper tree maintenance is crucial to reducing damage during very high winds. But although we love our trees, most of us are experiencing budgeting issues and tree pruning or investing in quality tree pruning is often not at the top of our priority list.
Here are some issues that can make your trees susceptible to wind damage and how to prevent it. Some are common sense and other more technical. Damage may be caused by one or a combination of factors (not all listed here).
Wrong tree in the wrong place
For most of us it is too late. We have large trees planted long ago in a small space, or a heavy rooting tree next to concrete, etc. Certain trees are more susceptible to wind damage. How we deal with maintaining the “wrong tree” is important and all the following issues become more critical.
Top heavy trees
Common sense tells us that this is strictly leverage. Trees with a lower center of gravity are less likely to break than those with a higher center of gravity. Reducing the length of certain branches helps create a lower center of gravity on those branches and might help contribute to their survival in windstorms. Reducing the entire crown size should also reduce damage potential.
Balance, structure, and trunk taper contribute to helping healthy trees be resilient to winds. To maintain resilient trunks, at least one-half of the foliage should be in the lower two-thirds of the tree. The lowest limb should originate in the bottom one-third of the tree’s height.
Trees not pruned or thinned often enough
The obvious reason for this is that the foliage can act like a sail. The trees become top heavy and /or out of balance, dead wood is not removed, weak branches and crotches are not removed, prior pruning mistakes or wind damage is not mitigated, disease and pest problems are not identified along with a score of other reasons especially creating the need to over-prunewhen pruning is finally done.
Trees overly pruned - removing too much of live wood of the tree at one time
More severe pruning slows root growth by shifting the root to shoot growth ratio. This adds significant stress to the tree. Heavy pruning also reduces carbohydrate reserves, making the tree less tolerant of insects, diseases, and drought stress.
Trees improperly pruned or topped (especially if the tree structure is negatively impacted)
Trees should never be topped; multiple shoots develop without a central leader. The tree becomes weak, top heavy, inevitably the wrong shoot or shoots will dominate and the tree will be weakened both aesthetically and structurally.
Most trees are grown with one central leader (the top most vertical branch). Exceptions are trees such as crape myrtle, that have been pruned to develop multi-trunks. A tree that will grow to more than 40 feet should have a single trunk well up into the canopy, but the trunk does not have to be perfectly straight.
Shallow roots from watering too often or not enough, bad soil or subsurface conditions
When the trees are irrigated too often the roots have no need to go deep for water because they have what they need without the effort of growing downward. When the subsurface becomes saturated over a period of time, with no oxygen and no biological activity, existing roots may die and new roots will grow to the surface looking for life sustaining matter. Over saturated ground and/or shallow roots will have obvious negative effects on anchoring of the trees.
When trees do not get enough deep water they will send roots to the surface or under concrete looking for water and nutrients. The roots won’t grow deep if there is no water to grow to. Under watered trees will stress and that will affect top growth, root growth and general tree health.
The trees in our region are a treasure. They add so much value and pleasure to our landscape, life and health. Let’s do our part in taking care of them.
If you would like to read a more technical version of this article or would like to read other articles on the landscape or sign up for our newsletter you can by looking under garden tips section at www.garden-view.com.