Last winter, Dave Poe, the manager of CVTS-L’s Adams County branch, was called out to assess a prominent white oak tree on the grounds of Hanover’s historic Eichelberger building. The tree is one of the oldest – if not the oldest tree – in Hanover, and it was certainly one of the largest that any of our offices had worked on in a long time.
The tree is a point of pride for the property and Poe was brought in to provide recommendations that would preserve the already generations-old tree for future generations.
And Poe was uniquely qualified for the job.
Like all of our arborists, Poe is perfectly capable and highly skilled when it comes to performing removals, prunings and diagnostics, but Poe’s real passion is tree preservation.
Previously, his office has proudly assisted with the specialized work of preserving Gettysburg’s Witness Trees (trees that ‘witnessed’ the Civil War). In addition to age-related problems, those trees sometimes bear physical scars, damage and even bullets from the battle, and the techniques involved include cabling, bracing and lightning protection. Read more about our work with Gettysburg’s Witness Trees here.
For the Eichelberger Building’s legendary white oak, there were two major concerns:
- The safety of the people working and traveling in the vicinity of the tree
- The preservation of the local landmark for historical and aesthetic purposes
To achieve these goals, Poe recommended strategic pruning (for the safety of the people below the limbs as well as the general health of the tree), fertilization (to promote good health), and lightning protection.
The Risks Posed by Lightning Strikes
A lightning strike can be devastating for a tree, causing long-term damage or even killing it instantly.
While lightning strikes themselves seem random, the behavior of lightning once it strikes an object is predictable enough that we can take preventative action to prepare for it and reroute it.
Without protection, lightning will strike near the top of a tree and follow the easiest, most conductive path to the ground. Unfortunately, the lightning’s preferred path will be through the tree’s cambium layer or sapwood layer, which is located just below the bark.
The sapwood layer is vital to the tree because it facilitates the flow of nutrients from the roots to the leaves and vice versa. When it is damaged by lightning, the tree will then have to deal with the initial injury caused by the strike as well as the long-term complications caused by reduced nutrient flow.
While it’s possible that the lightning can blow all of the bark off of an entire tree with a single strike, it’s more typical to see a strip of bark blown off indicating the flow of the lightning from the canopy to the roots. It’s not unheard of for lightning to blow the roots right out of the ground.
Sometimes the tree will survive and heal over, but – like the Witness Trees in Gettysburg that still have bullets lodged in them – the tree will likely bear the scar for the rest of its life.
The lightning protection doesn’t prevent lightning strikes, but instead, it provides a more conductive alternative for the lightning to follow instead of the cambium layer. The lightning strikes the canopy and is rerouted harmlessly into the ground.
The Lightning Protection Installation Process
For the pruning, we were able to work the outside of the tree with bucket trucks, but on account of the tree’s height, we also had multiple climbers up in the tree.
Additionally, we had people on the ground digging the trench and burying the wire. The underground utilities were carefully and clearly marked – the last thing you want to do is reroute the lightning protection pass into a nearby water or sewer pipe or other underground utilities.
When installing lightning protection, copper wire is attached to the highest point in the tree. If the crown is exceptionally wide (as this one was), the wire is attached to different locations at the top in case lightning strikes on one side of the tree or the other.
Those attachments are then tied together on the trunk and run down to the base of the tree using the straightest path possible from top to the bottom.
At the bottom, we dig a ditch that will conceal the wire underground, and then the wire is tied into ground rods, which are pounded 4-6’ into the soil to safely ground the electricity from the lightning strike.
Candidates for Lightning Protection
While every tree can benefit from lightning protection, not every tree needs it.
We generally recommend lightning protection for high-risk trees – those that are exceptionally tall or on top of a hill – and prominent trees that have high-value items beneath them such houses or cars; anything that can be damaged by falling limbs or trees.
We also recommend it for historical trees that people want to preserve and protect such as the Eichelberger white oak or Gettysburg’s Witness Trees.
Certainly, the Eichelberger Building’s white oak tree qualifies for both of these categories.
Learn more about the history of Hanover’s Eichelberger Building here.