Daytona City Hall Oaks

Excerpted from the article, Cabling and Consulting: Connections for Safer City Trees, by Guy Meilleur from The Australian Arbor Age, December, 2008, pp. 54-58.

The historic Thoburn Oak has been here before Daytona Beach was settled and was now facing removal.

The historic Thoburn Oak has been here before Daytona Beach was settled and was now facing removal.

In 1876, the city of Daytona Beach, Florida was founded in a forest of live oak, Quercus virginiana, which covered much of the southeast coastal region of the United States. Most of that forest was removed to make room for the growing city. Historian Harold Cardwell said about one live oak, “This city has had many changes over time, but the tree has always been there”.

In 1975 Cardwell, then a landscape architect,appraised the tree for Dr. Robert Thoburn, a dentist who owned the property on which the tree grows. Before selling his property to enable an expansion to the city hall building, Dr. Thoburn wanted to ensure its preservation by including the value of the historic tree, which Mr. Cardwell said was in pristine shape. At the time, Mr. Cardwell estimated the tree was 240 years old, using the rough guide for live oak of one year per inch circumference at the base. He appraised it at $75,000 based on a replacement cost formula, using the amount that Disney World spent to move the Liberty Oak and establish it at its Liberty Square location. Cardwell was not surprised to learn that arborists today are using a similar replacement cost method to appraise large trees, as described in the current 9th edition of the Guide for Plant Appraisal. He estimates that the tree’s value today could be $150,000, but its historical value is “priceless”. He noted that the city fathers routed the two main roads around the tree, so when these roads were later widened the tree lost critical roots.
On July 7, 2008 a branch fell from a nearby live oak onto the walkway leading to city hall, so the city paid for a risk assessment from an ISA Certified Arborist on that tree and the Thoburn Oak. (see the second photo below.) In a one-page letter dated July 18, the arborist proposed removing both trees. He said that they posed a danger to the motorists and pedestrians who pass under them each day, but gave few details. Tree risk formulas typically rate the severity of the defect, the size of the defective part, and the “target rating”, or use of the area under the tree. Next, management options to lessen or “abate” the risk are considered, before recommendations are made.

“Development of abatement options should be as systematic as development of the ratings… cable/bracing and/or reduction of end weight may be required…”, according to A Photographic Guide to the Evaluation of Hazard Trees. This arborist later said that “Target rating is the most important factor for me. If there’s a lot of use under the tree it’s dangerous, no matter what you do.”

The city’s Tree Advisory Board rejected this defensive report, and decided to get a second opinion before the city decided the fate of two of the city’s most visible historic trees. The board’s chair agreed, saying “I’m not comfortable recommending anything until I know more about these trees. It feels like these trees have a cold and we’re proposing to euthanize them.” However, another member said he’s observed them for the last 40 years and “these trees have lost the capacity to grow. I don’t see spending more for something that’s so obvious.” He predicted that in the next year “there won’t be a leaf left,” on the trees.

Another historic tree on Daytona Beach City Hall grounds was hit by lightning in 2008 and suffered some damage. Two local arborists called for its removal. Lippi, Meilleur and three other consulting arborists intervened saying the tree could be saved.

Another historic tree on Daytona Beach City Hall grounds was hit by lightning in 2008 and suffered some damage. Two local arborists called for its removal. Lippi, Meilleur and three other consulting arborists intervened saying the tree could be saved.

The board compromised, hiring another ISA Certified Arborist to get a second opinion at a lesser cost. In his letter accepting the assignment, this arborist agreed to assess the tree, give recommendations, and provide an estimate for doing the work. For a risk assessment or any report to be reliable, it should be completely independent, unrelated to estimating the sale of other services. Despite the apparent conflict of interest from blending an estimate into the assessment, the report went forward. Its recommendation was to remove the first tree and to prune the Thoburn Oak along with injecting fertilizer. Not surprisingly, that company uses the same proprietary product and method that was recommended. The work was scheduled for the following Saturday.

BCMA/RCA Chuck Lippi and five other consulting arborists from around the region (including the author of these two articles, Guy Meilleur) were concerned about this landmark tree and the opinions rendered thus far by the two arborists hired by the city. So Lippi, Meilleur and three other consulting arborists assessed it at no cost to the city. A summary of their report published in another arboriculture trade magazine follows below.

Thoburn Oak Observations

Excerpted from the article Cabling and Consulting: Connections for Safer Cities by Guy Meilleur in TCIA Magazine, January, 2009, pp. 38 -39.

Nine feet above ground, the trunk forked into four scaffold limbs. Three years ago, one limb failed and was cut back to the trunk. Anew branch is growing next to
the stub. The limb growing to the northwest is declining; many of its small laterals and twigs are leafless. Below this limb there is decay in the outer trunk at ground level, 30 inches wide, facing the sidewalk. Resistograph readings showed that the decay is only 1-2 inches deep, but probably deep enough to prevent good uptake of any injected material. The sidewalk meanders slightly around the trunk. The panels near the tree appear newer, and the edges of some have been ground down, apparently in response to upheaval by expanding roots.

A palm tree growing in the cavity was pulled out easily, because the roots stopped where a 3-inch layer of concrete was installed to “cap” the cavity. Where this concrete met the declining limb there is a thick bulge of tissue, showing that the concrete blocked the flow of sap, making the limb less healthy and less stable. The standards on tree support state that “Treatment of cavities by filling shall not be considered to provide support,”4 which is one reason cavities are seldom filled today. A streak of decay extends from the cavity between the declining limb and the limb growing toward city hall. There is no crack forming, and the Resistograph again showed that the decay is only 1-2 inches deep, with 17 inches of undecayed holding wood. Pruning will reduce the considerable load on this minor defect, and adding supplemental support can prevent failure in the future. Although both limbs are almost horizontal, they each have upright lateral branches that are large enough and vertical enough to hold a cable. The standards call for a 5/16- inch Extra High Strength cable to support limbs of this size, so a 3/8-inch cable would be super adequate. Drilling through both limbs and installing a brace rod could be done to add more support in the future, but the additional wounding and expense does not seem warranted now. With the cable installed, the pruning can be limited to dead, dying and the most overextended branches. The southwest limb has little root disturbance underneath, so it has high vitality. Lightly pruning the heavy end near the wires would increase the tree’s symmetry and stability.

Management options

  • Prune dead, dying and overextended branches
  • Install a 3/8-inch steel EHS cable to support the decayed fork
  • Remove concrete carefully, avoiding bark damage
  • Test the soil or leaf tissue and add nutrients that are lacking

In other words, the Thoburn Oak problems could, in the opinion of all five consulting arborists, be mitigated (made safer) through reduction pruning techniques and cabling and the tree could be retained.

Meilleur added in the same article:
According to Matheny and Clark1, “Almost by definition, arborists have a responsibility to care for trees,” and that duty is not breached if we act in a reasonable manner. Offering opinions about trees’ dignity or decrepitude without analyzing the facts is not part of a professional risk assessment. Members of the American Society of Consulting Arborists (ASCA) follow their Standards of Professional Practice, Item 4.2 G: “Members shall not take advantage of their positions as Experts by assigning or implying greater significance to an interpretation than it warrants. The degree of certainty of an opinion is as important as the opinion itself and Members shall do nothing, actively or passively, to misstate the degree of certainty.” Instead of reporting defensively by
injecting opinions or exaggerations, we should be systematically assessing stan-
dard treatment options to abate risk. If the treatments follow the standards and the best management practices, there is no reason to fear liability from working on trees that some would dismiss as “decrepit” or reject as “weed species.”

Conclusion (by Guy Meilleur)

I hope this article clarifies the usefulness of systematic assessment and abatement of tree risk as opposed to doing a defensive report. A little tree care can go a long way toward making trees safer. As Harold Cardwell said about the historic oak, “It’s bad: Neglect,… the roots being pushed by the sidewalk and all. It could have been root-fed and pruned, but nothing’s been done to it. A tree is like everything else; a certain amount of care is required.”
1 A Photographic Guide to the Evaluation of Hazard Trees, Second Edition by Nelda P. Matheny and James R. Clark, published by the ISA, Page 59
Guy Meilleur is a friend, a colleague, a frequent visitor to Florida and collaborator on several projects with me. He is owner of Better Tree Care Associates in Apex, North Carolina.