Pensacola News Journal

For:  Saturday, Nov. 27, 2004

By:   Daniel E. Mullins

        Extension Horticulture Agent

        Santa Rosa County

 

Wind Resistance Now a Key Factor in Tree Selection

 

            Many new trees will be planted in Gulf Coast landscapes over the next few months.  Though there are several considerations when deciding upon the kinds of trees to be established, wind resistance has become one of the most important.  The main question these days is:  “Which trees would be the most likely to remain standing during future storms?”

            Horticulture and forestry specialists have collected a lot of information to help answer this question. Tree damage surveys were performed following several hurricanes including Erin, Opal, Andrew, Hugo and Camille.

            Even though much information has been obtained there is still no complete wind resistant tree list.  Professionals who survey tree damage are very thorough and don’t feel that all potential tree species have been studied in enough detail. 

            With that said, some things appear obvious when gleaning information from tree damage surveys.  First, there is a short list of more wind resistant locally grown trees that is common.  According to Dr. Ed Gilman, Horticulturist with the University of Florida, these include Live Oak, Sand Live Oak, Sabal Palm, Southern Magnolia, Sweet Gum, Holly, Sycamore, Swamp Chestnut Oak, Baldcypress and Blackgum.

            Trees with a dominant central trunk growth habit appear to be more storm resistant.  Some of those on the list are believed to tolerate more wind because they naturally have a central leader. 

            It is also important to know which are the weaker, or less wind resistant trees.  Of the conifer species, sand pine (Pinus clausa) exhibited poor wind resistance, with 40 per cent blown down by Opal and about the same percentage of those remaining lost to Erin.  Longleaf and Slash pines fared much better during the same storms, ranging from a ten percent loss of longleaf during Erin to only four percent loss of slash pines during Opal.

            To further complicate matters, some preliminary information related to Hurricane Ivan doesn’t appear to jive with tree damage from Erin and Opal.  In the case of red maples, 41 percent were lost in the path of Erin while they appeared to hold up well during Ivan.  Apparently the last storm blew the leaves from this species prior to stronger winds, enabling them to better stand.

            Forty per cent of red cedars were destroyed during Opal and possibly more than that went down during Ivan.  Large Leyland Cypress trees were hard hit, but the percentage blown over during the last storm is currently unknown.

            Residents are encouraged to learn more about past hurricanes’ effects on trees.  A recommended document is “Wind and Trees: Surveys of Tree Damage in the Florida Panhandle after Hurricanes Erin and Opal.”  It can be obtained at your local Florida Extension office as IFAS Circular 1183, or go online and print a copy.  The site address is rather long, so search by typing IFAS Wind and Trees.

            I am looking forward to some official documentation related to tree loss from Hurricane Ivan.  Most information that I have collected is informal, consisting of photographs, talking with affected homeowners and from examining affected trees and neighborhoods.

            Tree damage data in the Pensacola area was collected shortly after Hurricane Ivan.  Dr. Mary Duryea of the University of Florida now has data from this and seven other hurricanes that is being processed.  She will share the results of the survey soon and promises to provide a more refined list of storm resistant trees.

Question of the Week:  Last year I fertilized a large live oak by digging holes and putting the fertilizer in the holes.  Is it too late to do that this year or should I skip this treatment.

Answer:  The fertilization of mature shade and ornamental trees in the landscape is not recommended.