Tree islands can protect your home during hurricanes
Now that summer has arrived, you may agree that shade is a wonderful thing. I prefer to stand it in and park my car in it whenever possible. If you would like to add some shade to your landscape and protect your home at the same time, consider creating a tree island.
Research shows that trees in groups survive winds better than trees growing alone. Scientists at the University of Florida/Institute of Food and Agricultural Sciences (UF/IFAS) studied this after 10 hurricanes struck Florida and the Gulf Coast. In Hurricanes Ivan and Jeanne, they found that trees growing in groups survived the winds better than individual trees — 80 percent versus 70 percent in Hurricane Ivan, and 88 percent versus 78 percent in Hurricane Jeanne.
The definition of a group was defined as five or more trees, each growing within 10 feet of another but not planted in a row. The research also showed that the more rooting space the trees have to grow in, the less likely they are to fall. Trees need adequate soil space to develop a strong supporting root system. Small-growing trees — those that grow 25 feet or less — require at least a 10-by-10 rooting area. Medium-sized trees, which grow 25 to 50 feet tall, need a minimum of a 20-by-20 rooting area, and large-growing trees, those 50 feet or larger, need a minimum area of 30-by-30.
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Scientists also found that some trees species have better wind resistance than others. Wind resistance is defined as the ability or capacity of a tree to survive, or remain alive and upright, during hurricane-force winds. This means that they are not easily uprooted or don't suffer broken limbs from wind damage. Using the research findings, along with information from arborists, scientists, urban foresters and scientific literature, scientists classified broad-leaved, conifer, palms and fruit tree species into four categories of resistance. Those categories include highest, medium-high, medium-low and lowest wind resistance. Some examples of the highest wind-resistant trees include Dahoon holly (Ilex cassine), Crape Myrtle (Lagerstroemia indica), Southern Magnolia (Magnolia grandiflora), Turkey oak (Quercus laevis), Live oak (Quercus virginiana), Podocarpus (Podocarpus spp.), Bald cypress (Taxodium distchum) and Pond cypress (Taxodium ascendens).
So, if you're interested in adding a tree island to your landscape, make sure to plant a minimum of five together. Not only will you want to plant them close, no more than 10 feet apart, but you will also want to plant different types together. Diversity in the landscape is very beneficial, so aim to have no more than 5 percent of the plants in your yard from the same genus and species, no more than 10 percent of the plants from the same genus and no more than 15 percent from the same plant family.
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The last thing to consider is the age of the trees, as it is best to plant trees that are of different ages. I recommend planting smaller trees, say 1 to 7 gallons, for faster establishment. You could either plant all of the trees at once, making sure that you have a variety of ages, or you could plant a couple trees this year and in a few years plant a few more and so on. You can create the shape of the tree island at the very beginning and just bury the entire area with a very thick layer of mulch, which will benefit the soil.
A tree island can provide a number of benefits to any lawn. Some of the benefits include attracting wildlife, providing shade, cooling effects for the home if situated on the west side of the house, reducing turf area and protecting the home during high-wind events. My recommendation? Start planning now!
Sally Scalera is an urban horticulture agent and master gardener coordinator for the University of Florida’s Institute of Food and Agriculture Sciences.