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Guest column

If pine could opine: It's safe under me

By ALAN MAYBERRY
Published September 7, 2005

I feel compelled to defend one of our finest native shade-tree species that was essentially trashed in a recent story in the St. Petersburg Times (Tree dispute remains unsettled, July 22). I do not dispute that the trees that were the subject of the article (located in a yard in Safety Harbor) are hazardous. I am sure the experts made the correct call. I take issue with the generalizations made about the species.

The tree in question is the slash pine tree with the botanical name of Pinus elliottii. The article quotes the arborist hired by Safety Harbor as saying that slash pines "are No. 1 in Florida for being lost in storms" and, "I wouldn't want to be living under them."

The inference is that the slash pine tree is not safe if growing around our homes. In my opinion, this is simply not true.

I retired from Clearwater as urban forestry manager in 2004 after 30 years. I enforced the city's tree protection codes for 14 years and later was in charge of the Urban Forestry Division, which handled the city's tree maintenance. I have conducted more than 2,000 inspections related to trees, including the damage incurred from two no-name storms, several near-scrapes with hurricanes and two severe droughts.

In the no-name storm of 1991, I toured Clearwater with the city manager and observed that more than 600 sand pine trees fell, but only one slash pine. The sand pine is a native pine tree that has proved to be a very poor urban tree. Numerous oak trees and tropical hardwood species such as the ear tree also fell then.

Until the storms of 2004, I cannot recall an incident when a slash pine tree failed. I was employed with Boen's Tree Service when the winds from Hurricanes Charley and Frances caused trees to fall, and Boen's removed several of the fallen slash pine trees from the Rainbow Farms neighborhood in Safety Harbor. I inspected the trunks and roots of the trees and the yards where they were growing and believe the trees failed for two reasons.

First, Bishop's Creek flows through Rainbow Farms, and much of the area is either flood plain or lower ground that became waterlogged. When soils are saturated and trees encounter high winds, they are susceptible to failure.

A second condition that contributed to the failure related to man's activities. The pine trees were there before development of Rainbow Farms and it was obvious that the native vegetation such as the saw palmetto had been grubbed away by heavy equipment. During this process, pine roots are severely damaged. Many of the pine trees I observed had decaying roots. Also, planting St. Augustine grass around pine trees leads to stress and decline in the native pines. Watering pine trees with well water that is typically alkaline will, over time, raise the soil pH to a level where our native pine trees can no longer absorb iron, which is an essential constituent of photosynthesis in pines.

I believe many of these trees were stressed and predisposed to failure. However, in upland sandy soils, which are our predominant soil type, I only witnessed failure of the sand pine.

If it is true that the slash pine tree is No. 1 for failure in Florida (I would like to know who counted them), it is because there are probably more slash pine trees than any other species. Pinellas County was named after the slash, longleaf and sand pine trees. In Hurricanes Hugo and Andrew, tens of thousands of pine trees growing in saturated, low-lying coastal areas fell, and perhaps this is where the slash pine gets its bad rap.

Coincidentally, the July 23 edition of the St. Petersburg Times' Garden section had a feature article on wind-tolerant trees (Strategic planting). In this article, author Pamela Crawford, who wrote a book titled Stormscaping: Landscaping to Minimize Wind Damage in Florida, is said to have visited areas hit hard by storms and then proceeded to interview residents, horticulturists and other experts. The article lists 17 tree species that have low wind tolerance, including sand pine, laurel oak and water oak, but does not mention the slash pine.

Perhaps the state's leading expert on the issue of tree-related storm damage is Dr. Ed Gilman, professor in the environmental horticulture department at the University of Florida. He has a wealth of information that can be accessed by clicking on the topic of storm damage at hort.ifas.ufl.edu/woody/pruning.

The slash pine is one of our finest native shade-tree species. No tree is storm-proof. Trees and people exist closer together than ever. Is the answer removing all the laurel oaks, water oaks, red cedars, and so forth?

What we need is an educated public. People have to take their trees seriously and should have them inspected by professionals to ensure that they do not have structural defects or systemic dysfunction that could lead to failure.

Because we seem to construct more buildings than plant trees, I hope we don't start removing trees for unwarranted purposes. Decisions to remove trees should be based on good science and made on an individual basis. We need trees more than ever. I live beneath pine trees, including two slash pines, and I am thankful for it.

Alan Mayberry is a certified arborist who lives in Clearwater.

[Last modified September 7, 2005, 01:01:15]