Woodbourne Forest. Photo © George C. Gress/TNC

The Mighty Guardians of Woodbourne Forest – Part I

Woodbourne: The Mythical Forest

Red oak in Woodbourne Forest. Photo © George C. Gress/TNC
Red oak in Woodbourne Forest. Photo © George C. Gress/TNC

“Wow, what an amazing tree,” I murmur aloud as I look up at the enormous eastern hemlock towering above me. Its massive limbs stretch out among other trees like a father gathering and embracing his family. This patriarch, guardian of the forest, casts a deep shade over the floor below, allowing only a few tiny shafts of light to reach the ground. Here, dozens of tiny hemlocks grow – each waiting to take its place among its colossal comrades.

As I gaze upward, I try to comprehend the enormity and age of this magnificent tree, wondering what events had happened during its lifetime. Perhaps it was already a sizeable tree when the Declaration of Independence was signed. Maybe it was a sapling when the first European explorers set foot on North American shores. One thing that I do know is that it was already a large tree when The Nature Conservancy acquired 478 acres of this old growth forest in Susquehanna County, Pennsylvania – and established the Woodbourne Forest Preserve. That was nearly 60 years ago, in April, 1956.

Woodbourne Forest is almost mythical. There are trees of all sizes here; huge red oaks, white pines, sugar maples, beech, and white ash trees – this type of diversity is largely absent from today’s forests. Walking silently among them, I’m in awe.

The giant patriarch I’ve been intently observing is tree number 1101. It measures over 44 inches in diameter and has stood for hundreds of years, silently guarding the forest and protecting the wildlife that have found refuge in its limbs and deeply wrinkled bark.

It has weathered many storms and survived many winters, and I cannot imagine a force strong enough to topple it. Unfortunately, the landscape is changing, and the eastern hemlocks of Woodbourne Forest are indeed under attack.

Forests Under Attack

The threat is not by chainsaws or bulldozers, but a tiny insect native to eastern Asia, accidentally introduced into the United States in the early 1950’s – the hemlock wooly adelgid (adelges tsugae).

While the insect itself is barely visible with the naked eye, its signature white egg sacs look like small tufts of cotton on the underside of the needles. When these tufts appear, the tree has already suffered several years of stress. The wooly adelgid feeds on the sap of a tree, slowly draining it of its life. It has been found in at least eleven states, and has desecrated over half of the range of the eastern hemlock.

Without intervention, it could wipe out the eastern hemlock.

Hemlock wooly adelgid. Photo © Nicholas Tonelli
Hemlock wooly adelgid. Photo © Nicholas Tonelli

Some scientists have labeled the potential loss of the eastern hemlock as catastrophic. Coupled with stresses related to a changing climate, the attack of the wooly adelgid could possibly be the tipping point for these delicate forest ecosystems.

But the wooly adelgid was certainly not the first invader to attack Penn’s Woods, nor will it be the last.

The emerald ash borer (Agrilus planipennis), a brilliant green beetle native to Asia and eastern Russia, was first confirmed in Michigan in 2002 and has spread to at least 23 states and two Canadian provinces. Commonly called EAB, it burrows into the cambium layer of the tree, effectively girdling it and cutting off its food supply. Infestation usually starts at the top of the tree, often going undetected until it is too late.

EAB was first confirmed at Woodbourne in March, 2014. Roadside ash trees were removed to prevent potential hazards. The remaining trees will eventually succumb to the EAB – becoming feeding grounds for wood boring beetles, which will feed woodpeckers and other insect eating birds before the trees collapse into the forest, returning to the earth, and nourishing other trees that will replace them.

Today, there are certainly many threats and obstacles to overcome if this forest is to survive. But the news is not all bad and there is a glimmer of hope.

By George C Gress, Land Steward / Fire Specialist

Read the conclusion of “The Mighty Guardians of Woodbourne Forest” — to find out how the Conservancy is combining the latest technology with proven treatment methods to ensure the hemlock’s legacy.”

Opinions expressed on TALK and in any corresponding comments are the personal opinions of the original authors and do not necessarily reflect the views of The Nature Conservancy.
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