Tsuga canadensis, the Eastern hemlock, was one of the dominant trees in our state’s forests.

When our first settlers arrived, “Penn’s Wood” was 90% forested.

Towering hemlocks and white pines were quickly utilized for many things in our emerging state.

The timber industry boomed in the 19th century. It employed workers in the winter months to cut and drag out the monster trees, and then spring and fall, to move them to sawmills and have them processed.

Hemlock was used for sheathing, posts, railroad ties, etc.

Our major rivers provided the best method for getting the timber to the mills. Rafts of hundreds of tree trunks floated down the rivers. In the 1890s, a billion board feet of hemlock was harvested.

Later, lumbermen realized the great need for tannic acid and then, very wastefully, the seemingly never-ending forests of hemlocks were soon cut just to use the bark. Hemlock bark supplied the tannic acid needed for tanning leather. So as settlers moved westward across the U.S., many raising cattle, the leather industry boomed.

In typical human wastefulness, millions of hemlock trunks were left to rot after only utilizing the bark. Today, now that these towering trees have regrown, they face another threat. This threat is worse than clear-cut timbering: It is the hemlock woolly adelgid. That is the battle the Eastern hemlock may lose.

I’ve written about the relationships throughout nature and how losing one important organism can have rippling effects. The jury is still out on the near extirpation of our small bats, especially the little brown bats, long-eared bats and tricolored bats. We know there will be ramifications. Well, the hemlock losses will have major implications, too.

Hemlocks thrive best on north and east facing mountainsides. Their canopy makes it ideal for rhododendrons, witch hazel and viburnums to grow. They are great at capturing carbon dioxide, helping to reduce the effects of global warming by removing some of that carbon dioxide from the atmosphere.

The once damp forest floors beneath the crown of healthy hemlocks now dries quickly with so few needles remaining on the trees. That increases the chances of destructive forest fires.

Hemlocks also grow well alongside clear mountain streams. In fact, they are mostly responsible for helping to keep the water cooler by blocking the sun’s relentless rays. Our state fish, the brook trout, requires water temperatures to remain below 60 degrees to ensure there is enough oxygen for them. They are a cold-water fish species. Will we lose many of our state fish, too?

Our ruffed grouse population is tumbling. They roosted in the once dense foliage and will eat some of the hemlock cones. Black-capped chickadees, pine siskins and red squirrels all rely on the seeds. Maybe you have noticed fewer chickadees visiting your bird feeders the last 15 or 20 winters. Whitetail deer, usually surviving winter on the small fat reserves they built up from late summer, learned to seek shelter from cold winter winds in thick hemlocks stands.

Finally, with my passion for birds, one of my concerns is for the many species that for centuries have adapted to feed, and in particular, to nest in hemlocks. They are Blackburnian warblers, black-throated blue warblers, Acadian flycatchers and blue-headed vireos, to name a few. It is another challenge they now face to maintain stable populations. (If losing wintering areas in the tropics wasn’t enough of a challenge.)

“It’s not nice to fool Mother Nature.” How will so many organisms adapt missing an important cog in their surroundings? So, when the adelgids arrived here from Japan in 1951, they moved into habitats where they had no natural enemies. In Japan, the adelgids were kept in check by other organisms that evolved with them. This is similar to the introduction of the gypsy moths here from Europe. The gypsy moth caterpillars found a smorgasbord here and nothing to eat or infect them. The result: exploding populations.

In a future column I’ll delve more into the adelgids. And maybe, just maybe, some ways to combat them and save such an important part of our forest’s ecosystem. We need to try to keep these vital trees flourishing for generations that follow us here in Pennsylvania and planet Earth.

Test Your Outdoor Knowledge: All of these duck species breed in our region except: A. common merganser; B. Northern pintail C. wood duck; D. mallard duck.

Last Week’s Trivia Answer: The redhead is unusual as probably the only duck that lays eggs in other duck nests and raises her own as well.

Email Barry Reed at breed71@gmail.com