Door to Nature: The Eastern Hemlock Tree

(Left to right) Charlotte Lukes and Beth Bartoli stand next to Door County’s biggest Eastern Hemlock tree. Photo by Roy Lukes.

Years ago Charlotte and I visited our neighbors a few miles southeast of us and enjoyed wonderful stories by the homeowner, 92-year-old Alfred Flock. He told of their barn and house being framed and beamed with Eastern Hemlock that had been cut in their own woods when he was a child.

Even though hemlock lumber has been traditionally looked down upon by builders, it is perfectly suitable for framing when other straight-grained and more expensive softwood, such as Douglas Fir, is not available or affordable.

Exposed to the elements it rots very quickly. One of the wood’s unusual characteristics is that it twists as it dries, consequently holding nails as though they had been glued in place. Unfortunately Eastern Hemlock is prone to “ring-shake” whereby the wood will frequently split lengthwise along its annual rings. In spite of these apparent faults of hemlock lumber the Flock buildings are square, true and in excellent condition today.

Before the settling of the plains and the West, there must have been vast, somewhat pure stands of hemlocks in eastern Wisconsin. Gradually as expanses of prairie land were plowed and planted to wheat, there arose a large and growing need for horse harnesses. Leather tanneries, such as in Two Rivers (on Tannery Road in those days), flourished and with them, a need for hemlock bark rich in tannin.

(Left to right) Charlotte Lukes and Beth Bartoli stand next to Door County’s biggest Eastern Hemlock tree. Photo by Roy Lukes.

Huge virgin stands of these trees were gutted, boatloads of bales of hemlock bark were shipped to the leather tanneries located near good sources of water, and the majority of the enormous 36-inch or thicker trunks were left to rot in the woods.

It is not too common to encounter large stands of Eastern Hemlocks in Wisconsin today. Fortunately several small but good ones have been preserved, mainly through the efforts of Wisconsin’s chapter of The Nature Conservancy. What an awesome experience it is to stand in their midst in winter as well as in summer.

These trees are always latecomers into a woods simply because they demand the cool moist conditions that are not present in a young stand of trees. Being extremely shade tolerant they grow slowly but well beneath the canopies of other taller “parent” trees.

Ever so gradually the hemlocks overtake and do away with all but the most shade-tolerant species such as the Sugar Maple and American Beech. The constantly cool humid conditions required by a hemlock’s roots are insured due to the dense roof-like canopy produced by its broadleaved partners as well as by its own thick shade-producing crowns.

A climax maple-beech-hemlock woods lacks much understory of small plants. Given a 95 percent or even greater shade factor, along with rather acidy soil resulting from the hemlock’s fallen needles, not many plants can tolerate these conditions. It’s as though the hemlocks are insuring that their competition be reduced to the absolute bare minimum.

About 48 years ago a small fire at Toft Point near Baileys Harbor was triggered by an old Eastern Hemlock tree falling across some electric power lines. Later, after we had chain-sawed the tree off the road I was allowed to cut a few four-inch-thick cross sections of the lower trunk to be used in teaching. Much to our surprise there were approximately 225 annual rings in 12 inches of growth, the radius of the tree had a diameter of 24 inches at that point. That amounts to an outward annual growth of about one-19th of an inch!

The fact that Eastern Hemlocks are capable of withstanding rather severe trimming and shaping is perfectly exemplified by the drastic winter pruning some of them receive from the activity of Porcupines. Contorted and misshapen hemlocks are common in woods occupied by large populations of these spiny mammals.

Study a grove of hemlocks for a couple seasons and invariably you will observe White-tailed Deer and Ruffed Grouse who depend upon these dense canopies for protection. Black-capped Chickadees, Pine Siskins and Crossbills will be lured to the copious amount of seeds produced every few years by a large tree. Snowshoe Hares and Porcupines both relish the bark, twigs and young saplings, so expect to see these creatures there, too.

One natural living factor that can potentially, over a period of a few generations or more, do away with hemlocks in a region is the White-tailed Deer. I have challenged members of my classes, while hiking and learning in a climax maple-beech-hemlock woods, to locate some hemlock seedlings. As long as the deer population remained at its high level both the hemlocks along with the Sugar Maples would gradually disappear while the American Beech would thrive. Now, however, the beech bark disease is changing the picture, destroying stands of American Beech especially close to the Great Lake shores.

The Eastern Hemlock belongs to the Tsuga (SOO-ga) genus, the Japanese name for an Asiatic species. Its species name, canadensis, implies that it is a tree of the far north when actually it grows as far south as the mountainous regions of northern Alabama and Georgia.

Only small pockets of them grow as far west as Minnesota. They are common in the northeastern half of Wisconsin and extend eastward from lower Ontario to the Atlantic coast and Nova Scotia. The Eastern Hemlock has been chosen as the state tree of Pennsylvania while the Western Hemlock, Tsuga heterophylla, is the state tree of Washington.

Now a tiny aphid native to Asia, the Woolly Adelgid, is threatening the stands of Eastern Hemlock and Carolina Hemlock in 16 eastern states from Maine to Alabama. It was first reported in 1951 and may eventually affect all Eastern Hemlocks in the country.

I had a pleasant surprise today while reading the descriptions of the North American Hemlocks (Mountain, Western, Eastern and Carolina) as written in my two favorite field guides to trees. Having taught about evergreens for 51 years it came as a shock to read that the leaves (needles) of an Eastern Hemlock are toothed!

Out came my 10-power hand lens and, with several small hemlocks growing in our front yard, I was soon scrutinizing a single needle. There they were, fine and tiny, but nevertheless genuine teeth that must be looked for with a magnifying glass. Live and learn!

So many people will gaze in awe at the beauty and workmanship in a well-preserved 100-year-old building, yet hardly turn a head or blink an eye at a climax maple-beech-hemlock forest. Here for centuries subtle changes have gradually occurred to the point where, after several hundreds of years of growth, the end result has come about at last.

Barring catastrophic fires, drastic fluctuations in climate, tornadoes, too many deer or too much logging, here is a forest that will sustain itself and continue to produce more trees of its kind for centuries – a masterpiece not built by hands, a cathedral in the wild.