After the famed heat dome in the Pacific Northwest in late June, 2021, we saw some odd things.
In the forests of the Olympic Mountains, known for their mild-mannered, moisture-loving trees like Western Hemlock and Western Red Cedar, new growth tips were fried. And we saw other things that took a while to manifest.
Growers with young plants and those with older bonsai spoke of the same thing—under the bark, cooked tissue. Dead areas on the sun-exposed sides.
That year I started to pay attention to where the deadwood was on collected trees. Often you could see borer holes in old deadwood. But sometimes there were no holes. And that damage tended to be on the top side of a leaning trunk.
A collected conifer with deadwood on the sun-side of the trunk, a remarkably common situation
So it made me wonder. A conifer on a rocky break in a captive root situation is a stressed plant. On a hot summer day—not a heat dome week—that tree might be on the edge, susceptible. And where sun hits a trunk full on, it may parboil in its own juices.
Does intense sun create deadwood? Given what we saw in 2021, which multiple growers I spoke with agreeing, it appears it can. Much of what we see as deadwood on collected trees is borer damage, or some other sort of damage. But intense sun is one more stress factor that might on occasion be enough to create deadwood.