Blog

Preparing trees for the next hurricane

Preparing trees for the next hurricane

A weather forecast of hurricane-force winds evokes fears of (1) loss of life, (2) damage to property and (3) destruction of landscaped trees and shrubs in private and public gardens.  In the event of a hurricane, public agencies focus on real-time actions people need to take with regard the first two items.  As for the third item, private individuals (homeowners) and public officials (park and road agencies) can take precautions to minimize the amount of wind damage a hurricane can cause to landscaped trees and shrubs.  Wind damage can be mitigated to some extent by long- and short-term gardening practices.  Over the long term this involves the selection of tree species for landscaping which are known to have natural resistance to strong wind.  Four basic tree characteristics are associated with wind resistance.  One, a deep or extensive root systems to provide firm support, making it less likely to be blown over. Trees need to have sufficient space to develop their root systems and therefore should not be crowded by other trees, structures or pavement. Two, strong trunks and branches not prone to breakage.  Tree strength is related to wood density so that factor needs attention. Also, trees in general with horizontal branching are stronger than those with upright branches. Three, a more open canopy.  The test is of canopy density is if you can see through it, it is open.  Four, tree age and condition.  As a tree ages, it becomes less resistant to strong winds; moreover, a healthy tree similarly is more able to survive a hurricane.   Old and/or diseased trees should be removed as a precaution.   

The configuration of a garden is also important in terms of minimizing the risk of falling trees or limbs causing damage to structures or other plants.  Planting short trees or shrubs nearest to a building and larger trees some distance away is recommended. Knowledge of the most common direction of hurricane-force winds should be taken into account in garden planning and replacement plantings.  A tall shrub hedge, for example, oriented perpendicular to the wind direction may help to reduce the wind damage within a garden itself.  These long-term measures are most easily accomplished in the creation of a new garden, but an existing garden can be modified over time.

An existing garden of whatever arrangement can be managed to reduce potential damage from a hurricane.  Tree root systems can be weakened by root pruning or any excavations under the tree canopy, and these should be avoided to the extent possible.  Trees with multiple trunks are more vulnerable to wind damage than those with a single trunk because they are buffeted to a greater degree by winds.  It is preferable to prune away smaller trunks and allow just a few strong leaders to grow.  Branches should be inspected to identify those best removed because they are weak or may be infested by insects or birds.  Regular pruning or thinning of branches reduces the canopy density allowing strong winds to pass through rather than be buffeted and lead to tree fall or branch breakage.  Studies of the impact of hurricanes on trees in South Florida have revealed that certain species are more wind tolerant than others and have a greater chance of survival.  In general, conifers and palms fare better than broadleaf trees.  Also, native trees exhibit greater hurricane survivability than exotic species.  Taking actions in response to the above suggestions may see your garden come through the next tropical depression with less damage.  Examples of wind-resistant trees in the TreeWorld inventory include Red Maple (Acer rubrum), Dahoon Holly (Ilex cassine), Live Oak (Quercus virginiana) and Bald Cypress (Taxodium distichum).