The American beech has fallen on tough times. Twenty years ago, if you were to walk in the woods, you would likely be impressed by the smooth bark and the enormous size of a mature beech. You might also notice the husks of beech nuts littering the forest floor, evidence of a squirrel preparing for winter.
If you took that same walk today, you would be greeted by the scarred remains of a once healthy forest. The bark of these smooth trees is now peppered with exit holes from insects feeding on the decaying trunk. The ground is littered with debris after the tops have snapped off as the structure underneath decays. And where you could look out and marvel at the beauty around you, beech saplings have sprouted in what seems to be every inch of the forest floor.
Though the saplings might seem like healthy regeneration, the perceptive among you may realize that these new shoots are clones of the fallen trees that towered above, and are likely destined to the same dismal fate.
Our beech trees have been impacted by a destructive relationship between an invasive scale insect, beech scale (Cryptococcus fagisuga), and a handful of native fungi (neonectria spp.).
The scale insect, which looks like small, fuzzy, snow-like, white dots, colonizes a new tree where it penetrates the bark to feed on the sap. This creates an opening for the fungus to work its way into the vascular system of the tree where it can spread, eventually ceasing the transfer of water and nutrients throughout the tree, culminating in mortality.
The interaction of these two organisms is known as Beech Bark Disease and has wreaked havoc across the State of Michigan since 2000 with “devastating impact(s)”, according to MSU Extension.
This leads us to a difficult question; what is the future of the beech tree? It is impossible to answer with certainty, but we may glean insight if we set our sights to eastern Acadia: ground zero of Beech Bark Disease in America.
The beech scale insect made its way to the new world through Nova Scotia around 1890. Over the next 50-60 years, it spread westward through Prince Edward Island and New Brunswick, severely altering the forests in its path. This is where a team of Canadian researchers, headed by Dr. Anthony Taylor, looked to examine the frequency of trees resistant to the disease.
Although not a perfect comparison because of slight differences in temperature, precipitation, and topography, Acadia’s past will likely share similarities with Michigan’s future; and what the Canadian team learned shows some cause for concern.
Studies across the range of the disease show only 1% of observed trees are resistant to the disease. The hope would be that, given enough time, the resistant trees would survive and reproduce and healthy beech would repopulate the forests.
That is what the researchers saw: an increase to an average of 3% resistant trees. This is good news in that it shows evidence in support of the hypothesis, but it also shows that any real beech resurgence is likely to take place on a time-scale larger than our own.
Though this paints a bleak picture for the health of our beech in the near future, the results should not be taken as definitive. Regionality has a large effect and some areas are faring better than others.
If we compare the previous results with those of another study, this time led by William Leak of the USFS Northern Research Station, we can see an alternative to the narrative laid out by Dr. Taylor. Leak’s team looked at the 50-year impacts of Beech Bark Disease in the Bartlett Experimental Forest in New Hampshire.
Here they found forests that have actually increased their abundance of mature beech, including a managed stand that showed close to a 15% resistance to both insect and fungi.
Leak cautions that the findings should be taken with a grain of salt.
“The application of these results to other areas must be viewed with caution,” he said. “It is quite likely that other regions have different levels of genetic resistance to the beech bark disease, and possibly different strains of scale and Nectria as well.”
For beech, the challenges are many and more are added seemingly every day. Beech Leaf Disease, a separate disease that attacks and weakens the foliage of living beech, has taken hold throughout the eastern US and as of 2022 the Michigan Invasive Species Program has reported a presence in southeast Michigan.
Additionally, climate change predictions from the USDA and the USFS show that many hardwood species will gain suitable habitat throughout the UP, directly competing with the already struggling beech population.
Only time will tell how Michigan’s beech respond to this disturbance, but we should brace for the possibility that the forests of our future are not the same as our past.
For assistance in forest management, contact the Chippewa Luce Mackinac Conservation District by calling Louis Radecki, CLMCD forester, at (906) 632-9611 ext. 8055, or by email at louis.radecki@macd.org
