Included bark and the recent ice storm in Nashville

We just had a major ice storm in Nashville, and as someone who grew up in the subtropics of Australia, I can honestly say I've never seen anything like it.

Before the storm hit, a fellow arborist friend asked me — "Have you ever experienced an ice storm before?" I'd lived in Canada, seen some deep freezes here in Nashville over the last few years, and figured I had a reasonable idea of what to expect. I didn't think too much of it.

I was wrong.

The night the storm hit I kept waking up to the sound of cracking and snapping limbs all around my neighborhood. It was unsettling — like the trees were under siege. When I walked outside the next morning I couldn't believe what I was looking at. Trees and power lines down everywhere, cars smashed, roads blocked, and trees still snapping under the weight of the ice around me. The sheer immensity of it was something I won't forget.

As I walked through the neighborhood taking it all in, I found myself looking at the damage through a particular lens. I had recently been deep in the Ed Gilman video series from the University of Florida — fascinating stuff covering branch unions, aspect ratios, and included bark. Having just absorbed all of that material, I was now essentially looking at a real world stress test of those very concepts.

One thing stood out immediately — the Hackberry trees (Celtis occidentalis) had taken a beating far worse than most other species. And it made complete sense. Hackberries commonly develop multiple co-dominant stems, meaning instead of one strong central leader, they grow with several stems of similar size competing for dominance. Where those stems meet, you often find included bark — and that's where the failures were happening.

So what exactly is included bark? When two stems grow alongside each other and neither establishes dominance, they can press against one another without ever forming a proper wood-to-wood union. Instead of bonding, the bark of each stem gets trapped between them — bark against bark. This creates an inherently weak junction, one that lacks the structural integrity of a proper branch union. Under normal conditions it may go unnoticed for years. But put hundreds of pounds of ice on those stems and the weak point reveals itself fast.

Walking through the aftermath of the storm, the pattern was clear. Trees with good structure — strong central leaders, proper branch unions, balanced canopies — largely held up. Trees with co-dominant stems and included bark were the ones lying in the street.

It was a powerful reminder that tree structure isn't just an academic concept. It has real consequences for property, safety, and the long term health of your trees. Proper pruning when trees are young — removing co-dominant stems early, encouraging a strong central leader — can make all the difference when mother nature decides to test them.

If the ice storm left you wondering about the health and structure of your trees, we'd love to take a look. Sometimes the best time to assess your trees is right after a storm, when the vulnerabilities are most visible.