Trees and Hurricanes
Urban forests, including trees and shrubs, are a critical resource. They provide a host of benefits that support our health and prosperity. Hurricanes can be extremely damaging to communities and urban forests. During these storms trees can become hazardous and pose risks to personal safety and property.
Since 1992, when Hurricane Andrew struck South Florida, researchers at University of Florida/IFAS have been studying the impacts of hurricanes on the urban forest and trees.
The following is a series of lessons learned and recommendations drawn from these scientific investigations. If followed, they can help us all reduce risks to safety and property, while ensuring that the urban forest can continue to thrive.
Lesson: The higher the wind speed of the hurricane, the more likely trees will fail.
Recommendation: Establish and manage a healthy urban forest to improve wind resistance.
Lesson: Trees in groups survive winds better than trees growing individually.
Recommendation: Plant trees in groups of at least five trees as opposed to individually.
Recommendation: Plant a variety of species, ages and layers of trees and shrubs to maintain diversity in your community.
Lesson: Some species resist wind better than others.
Recommendation: Plant tree species that have been shown to be more wind resistant.
Recommendation: Consider removing over-mature and hazardous tree species that have demonstrated poor survival in hurricanes.
Recommendation: When a tree fails, plant a new tree in its place.
Become familiar with the recommended tree species and how they perform in natural and urban ecosystems in your community.
Lesson: As a group, palm species survive hurricanes better than broad-leaved and conifer trees.
Recommendation: Consider planting wind-resistant palm species
Recommendation: Monitor palms carefully after storms
Lesson: Pines may show no immediate visible damage after hurricanes but may decline over time
Recommendation: Monitor pines carefully.
Lesson: Trees that lose all or some of their leaves in hurricanes are not necessarily dead.
Recommendation: Wait, watch for leaves, and monitor the tree’s health.
Lesson: Native tree species survived better in South Florida hurricanes
Recommendation: Consider native tree species when selecting trees for planting.
Lesson: Unhealthy and declining older trees are predisposed to damage.
Recommendation: Remove hazard trees before the wind does.
Lesson: Trees with poor structure or included bark are more vulnerable in the wind.
Recommendation: For a more wind-resistant, sustainable landscape, plant high-quality trees with central leaders and good form.
Recommendation: Follow with a preventive structural pruning program of young and mature trees.
Lesson: Trees systematically pruned to meet or exceed national standards survive hurricanes better than poorly pruned or unpruned trees.
Recommendation: Begin a preventive pruning program for both young and mature trees.
Recommendation: Select the right tree for the right location to avoid poor pruning practices.
Lesson: Trees with more rooting space survive better.
Recommendation: Give trees enough rooting space based on their mature size.
Lesson: Good soil properties, such as adequate soil depth, a deep water table, and no compaction, help wind resistance.
Recommendation: Make sure that planting sites have 3 feet of soil depth with a deep water table to allow healthy root system development.
Recommendation: Keep soil compaction to a minimum.
Lesson: Damaged root systems make trees vulnerable in the wind.
Recommendation: Do not damage or cut main support roots during construction.
To learn more about what the University of Florida researchers learned about tree and hurricanes visit their web site at: http://hort.ifas.ufl.edu/treesandhurricanes/
FromL Duryea, M. and E. Kamph. Wind and trees: lessons learned from hurricanes. University of Florida publication FOR 118.