A Beech Tree and a Rare Genetic Trait
While walking in the Lambs Lake Nature Reserve, near Annapolis Royal, I spied a large, old-growth beech tree. Its massive girth caught my eye first (I could reach only about half way around it), but its smooth bark is what made me look twice. In that tree’s genetic make-up, I knew, there lay a rare and special genetic trait.
Beech trees were once more common throughout the Maritimes. In the early 1800s, beech were noted to cover roughly half of Prince Edward Island, for example. Aside from land clearing for agriculture and timber, beech were hit by a disease accidently introduced to Halifax from Europe in 1890. The beech bark disease, consisting of an insect and a fungus working in concert, spread rapidly throughout the Maritimes and into New England, drastically reducing populations of beech trees. While many beech are able to live with the disease for a time, they are marked by gnarled, cankered bark, resulting from the tree’s attempt to fight the disease.
As luck would have it, not all beech trees are affected by this disease. A few trees, roughly one to four percent, have a genetic trait (or traits) that makes them resistant to the disease. So it was with this massive beech tree that I spied near Lambs Lake. There, among dozens of cankered fellow beech, this tree with its lucky genetic make-up stood with clear, smooth, healthy bark, its branches forming a full crown high above. As in times past, this beech tree had taken its place as a dominant species in this forest. (Note, a few beech trees in the coldest parts of its range may be preserved from the disease by exceptionally cold winters, but this hasn’t been observed in Nova Scotia.)
I thought, as I put my hand to the tree’s smooth grey bark, about the importance of genetic diversity. Before the disease hit the Maritimes, this rare trait (or traits) had no obvious benefit. And that’s the thing about genetic diversity. It’s not so important for dealing with present problems; rather, genetic diversity helps populations of species to survive and adapt to new problems, to changing environments. This tree wouldn’t have been remarkable before the disease rolled through the Maritimes. Now it stands tall among its brethren of diseased beech: a lucky genetic twist of fate.
I can’t resist a good climbing tree, and healthy beech trees, with their smooth bark and many near-horizontal branches, are perhaps our finest climbing trees. The first branches on this tree were some twenty or so feet up, so I used a nearby smaller tree as a ladder into the big beech. I climbed up through the tree’s canopy, noting the layers of tree branches from close to the forest floor to the very top of the tallest trees. Old forests have lots of vertical diversity not easily seen from ground level.
At the top of the tree I poked my head through the canopy, blinked as my eyes adjusted to the bright sunlight, and looked out on an abundance of beech nuts. I noticed some broken branches, too, likely the work of a feasting black bear, who climb beech trees for their fat-rich nuts. Beech nuts are favoured by many species of wildlife, but are now much reduced in supply due to the disease. I opened a couple of nuts for myself, hoping for a snack after my climb, but I was too early and the seeds were far from ripe.
I thought about my lucky find as I continued my walk through that forest. Unfortunately, healthy beech are even rarer than they should be. Many woodland owners and foresters are not aware that some beech are resistant to the disease, and resistant beech are cut without thought to sparing them for their benefit to wildlife, and their rare disease resistance. While beech will not come to dominate the landscape again as they once did (at least, not any time soon), it’s worth identifying and protecting healthy beech, for the food they provide for wildlife, and for the possibility of one day seeing a few more healthy beech in our forests.
A bright note in the beech story is the results of research conducted by the Canadian Forestry Service, in Fredericton, NB. Over several years, a team of researchers successfully propagated beech trees that were resistant to the beech bark disease (I team that I was part of in its early days). Although the federal government cut the project, the young healthy beech were distributed to a national park in each of the Maritime provinces. Perhaps, one day, these orchards of healthy beech will be sources of beech nuts containing the genetic resistance to the disease. I’d like to plant a few on my property. Maybe a black bear or ruffed grouse would someday fill its belly with their nuts. Maybe a kid would someday climb high into their branches.
Originally published October 17th, 2014, Chronicle Herald