An Experienced Tree Risk Assessor Visits an Upstate Park

Published: April 21, 2025    Posted by: Randy Cyr    Estimated reading time: 15 minutes

A Visit to an Upstate Park

What would happen if an experienced Tree Risk Assessor visited an Upstate, South Carolina Park with large trees? Could he fully enjoy the park, like most others, if he became aware of potentially hazardous conditions in areas frequented by people? Would he cause needless panic if he warned the visitors? Should he alert park officials though it is their job to provide a safe park?

What if he learned other arborists rendered the park safe? If he minded his own business and went on his way, would he later feel guilt upon discovering someone had been injured? These are valid considerations from an arborist who loves the Upstate, its trees, and especially its people.

The Centerpiece of the Park

Due to my concerns, I cautioned the woman seated on the bench and subsequently reported this tree to the Superintendent. That was the prudent course of action. These observations were made by a visitor who happens to be an ISA (International Society of Arboriculture) Board Certified Master Arborist.

This large post oak (Quercus stellata), with its numerous, large, covered stub cuts (white ‘x’s’), caught my attention from a distance (white ‘x’ bottom center of top photo). After 37 years evaluating trees, I rarely see something new.

As I approached the aging giant, I noticed the huge, case-hardened wound below (red arrow), and the flush cut above (yellow x). Pruning wounds trees, which don’t heal like animals but form barriers to prevent infection (C.O.D.I.T.). Stub and flush cuts (see examples below) can cause decay to spread through vulnerable trees.

The abnormal angle (yellow arrow), branch stub (orange arrow), and likely decay from stub cuts (white arrow) entering the branch collar (branch attachment or union), are considered defects (structural flaws) which likely weaken branch strength.

I returned with a percussion hammer to find (through ‘sounding‘ or striking the tree) about 2/3’s of the butt (lower trunk) sounds like it may have significant internal decay (result of wood decomposition). Let us now examine this tree from the perspective of an ISA Tree Risk Assessor, keeping in mind that this is NOT an official Tree Risk Assessment.

Two mobile targets (woman sitting on bench and standing man adjusting his cap) with no protection within the target zone of a defective, rotten (decayed) branch above and a defective, rotten tree leaning in their direction (note shadow).

Healthy shade trees, with good architecture and live crown ratio (leaf-bearing crown percentage of tree), should ‘shade.’ While trees are more likely to fail during inclement weather, they also can fail in pristine conditions (Sudden Branch Drop Syndrome).

Tree Risk Assessment Matrix (p. 172)

Permanent restrictions may be impractical since this cherished tree is the focal point of the park. The likelihood of failure for the branch is probable, and for the tree possible within 1 year (although it withstood Hurricane Helene last autumn). The likelihood of failure and impact for the branch is somewhat likely, and for the tree unlikely. The consequence of failure for the branch is moderate, while for the tree low. But low does not mean no risk. What are some mitigation options that might reduce risk?

Temporarily restrict this tree and fence off the target zone so that an Advanced Tree Risk Assessment Level 3 can be conducted. Although this may be a low risk, the condition of the tree is likely to deteriorate further, increasing the risk it poses to visitors and staff in this small, busy park. Structures, vehicles, or safety helmets may offer some protection to individuals; however, these visitors remain unprotected.

The tree is centrally located with a target zone that may reach 1 1/2 times its height. An advanced assessment will require time and may be impractical due to budget constraints. Closing the park until the tree can be safely removed might be advisable, with appropriate justification. Let us continue our informal examination of this tree.

A Closer Look at a Post Oak’s ‘Feet’ 

Partial Root Crown Inspection

Dark green arrow: Green Tree Doctor’s bag

Light blue arrow: arborist’s trowel (or soil knife)

Red arrow: 6-inch soil profile shows no topsoil or soil animals (such as earthworms), with only compacted, clay subsoil

Dark blue arrow: less than 1 inch of compacted, double-ground, non-aged, non-dyed, woodchip mulch

Orange arrow: unidentified, hardened tan substance around root/trunk flares

Green arrow: Woundwood (woody, lignified ribs that close woody plant wounds) on old, land-development injury (possibly a decade ago)

White/black/yellow arrows: artificial landscaping turf within tree’s critical root zone

Stub cut (red ‘x’)/flush cut (red ‘x’)/natural target pruning cut (green ‘check’) x 4 trees

With the stub/flush cuts, defective branches, huge basal (trunk) wound (with likely, considerable internal decay), and likely injured buttress roots (large, structural, anchorage roots); maybe this relic should have been laid to rest before the park was built around it.

This is typical of trees without an arborist-supervised tree preservation plan (ANSI A300 and ISA BMP) during development (though this tree has been declining for several years). The topsoil has been stripped away, and the remaining clay subsoil is compacted (compaction is the silent killer of urban trees).

The root/trunk flares are likely severely damaged below ground, without soil animals present (which help till and fertilize), and sufficient beneficial microbes (most ‘developed’ sites have relatively sterile soil). The mulch should be 2 inches deep and tilled once a month during the growing season (with a garden rake to prevent compaction), and the mulch bed should be extended out 12 feet out from root/trunk flares (completely around the tree or proportionate area).

This thick, spongy artificial turf likely limits air, water, nutrients, soil animals and beneficial microbes from reaching the roots within the critical root zone. Trees frequented by the public are best rope-fenced off near the branch dripline (furthest extent of branches) to protect from shedding branches and the root zone from compaction due to foot traffic.

If these measures are unacceptable, signs warning individuals the potential danger of falling trees and branches could be advisable.

An Accident Waiting for a Happening

The backside of this post oak looks even worse (if not, otherworldly). Just the darkened, shedding bark, low crown ratio and abnormal appearance should be a warning.

The white ‘x’s’ show massive stub cuts with likely long columns of internal decay/rot. The white arrows point to the loss of bark and likely the brown, exposed sapwood (xylem) is decayed (without needing field glasses). The orange arrow points to a ripped-out branch (storm?) and a subsequent cavity (likely weakening tree strength and allowing decay to spread).

The leaning part of this tree above this point presents an increased risk to the public. The yellow arrow points to a cavity/defect. Green arrows point to adventitious sprouts with poor branch attachment that could fail (especially, as they grow larger).

Relying solely upon the ISA Tree Risk Assessment Matrix (above) might prove inadequate. The Manual and the Matrix serve as a guide, and arborist’s findings are subjective. Each individual branch and tree are treated as individual tree parts and each person individual targets. The risk of a branch hitting a target is moderate (the tree part with the highest rating) and the tree low.

Taken into account the totality of defective branches, and the many people walking, running, standing, sitting, swinging, and playing under these branches increase the chance of “someone” becoming seriously hurt (the definition of risk). This is a bottleneck for much of the park’s visitor traffic. Thus, the possible need for an advanced assessment, if not, removal (a decision for park, and regional management).

Post oaks are particularly tough and long-lived. Most other species would have perished long ago. In a different setting, it could have lived out its remaining days in leisure. But we have chosen to build a bustling park around this abused, deteriorating, and potentially dangerous tree.

A Long Way to Fall

While others see healthy, safe trees, I often observe defects and occasionally hazards. To be a hazard, there needs to be a defect and a target. I have observed defects and potential hazards in other trees. Let us look at one more tree in this park.

The branch on this water oak (Quercus nigra) represents an unacceptable risk to visitors using the swings below. The orange arrow points to likely decay which has spread from branch self-pruning (effectively, a stub cut allowing decay pathogens to gain a foothold).

The entire branch shows little taper, extending considerably out from the tree, with abnormal body language, and a disproportionate number of secondary branches towards the end (end-loading or ‘lion-tailing’). Exposure and loading from gravity and wind put considerable force upon the branch collar (white arrow) and a midpoint defect (orange arrow).

At one time, other branches and trees likely shared in loading (static and dynamic mechanical stress). Now this gangly branch stands alone and exposed and high above the swings. This branch still does not have any leaves (this is the third week of April). It is either dead, stressed or strained, and should be examined more closely, if not removed. This is the only part on this tree I considered in my informal examination. Anything which stands out warrants closer attention.

Losing large branches is rarely normal for healthy, stable trees (although we may become accustomed to it, and have dead branches periodically removed). A history or pattern of failure could point to more serious health and stability issues. Branches should be regularly inspected, as well as the trunk, root/trunk flares and root zone (especially greenspaces). Putting swings under this tree is not prudent. Possibly the swings could be moved (another decision for management).

Managers and arborists who maintain parks shouldn’t have to wait on a formal Tree Risk Assessment to decide to remove defective trees and tree parts which ought to be evident to professionals and part of periodic maintenance. Unfortunately, I have observed similar conditions in other Upstate parks.

This is an observation and not a formal Tree Risk Assessment. For further information, please refer to the ISA Tree Risk Assessment Manuel, Second Edition, or contact the Green Tree Doctor (864) 991 5003.

One of our Safer ‘Trees’

On the lighter side of things. Trees can be managed, but they cannot be controlled. To live and play near trees is to accept some degree of risk. What is an acceptable risk? Risk Managers should strive to strike a balance between the benefits trees provide and the risk they pose. The only way to eliminate all risk is to eliminate all trees.

While it is rare for people to be injured by trees, such incidents can and do occur. Parks with trees are good things. They are cherished and needed. But we have a responsibility to provide safe greenspaces. Photos © Randy Cyr