Eastern hemlock trees, conifers that were once the giants of the lumber business, are disappearing. A series of art installations along an interpretive trail in the 4,000-acre Harvard Forest in Petersham, Massachusetts, gives creative expression to this long and complicated story.
“Hemlock Hospice” is a collaborative work by Harvard Forest senior ecologist Aaron Ellison and artist David Buckley Borden.
The Harvard Forest is known as the “wired woods.” It’s a hotspot for scientific research on topics ranging from soil warming to atmospheric carbon exchange. At first glance, the forest looks like a typical New England forest. But look more closely and you notice all the hemlock trees are dead or dying.
Climate change is spurring the hemlock wooly adelgid (HWA), an invasive insect, to move further north. The insect kills hemlock trees by sucking out their sap. Spindly, bare branches are strewn about the ground and the decaying, gnarled trunks moan as they lean over one another.
“As most folks know, hospice care is end-of-life or end-of-term care ... designed to have a more dignified close to one’s life,” Borden says. “But it’s also intended to benefit the living, so they can have a positive experience — as much as one can when experiencing the loss of an individual or a species or an ecosystem.”
Ellison studies how ecological systems fall apart and how they put themselves back together again. This ecosystem first fell apart more than 300 years ago.
“This was an old-growth forest when Europeans showed up in this landscape in the 1600s and early 1700s,” Ellison explains.
"They didn’t have chainsaws and they didn’t have power tools," Ellison says, "but they had a lot of strength and a lot of willpower to make it something that we could use. So, they very assiduously cut down all the forest."
Over time, Eastern forests, including hemlock trees, grew back. Today there is actually more forest cover in New England than there was in colonial days.
The hemlock’s modern troubles started in 1951 when the HWA was introduced in Virginia. The HWA has left a wake of dead hemlocks from Georgia to Maine, and it will continue marching north as climate change creates new habitats for it. Already, it has reached southwestern Nova Scotia.
One of Borden’s works along the trail is called “Insect Landing.” Borden says the piece is a “prompt to talk about the introduction of the insect.”
“We talk about how the insect was introduced on nursery stock from Japan in the 1950s and how, over the course of the last 40 or 50 years, it slowly migrated north with climate change,” Borden says.
"People often talk about climate change in terms of the big storms, rising tides, mega-fires, and they’re all valid," Borden says. "But this is just as impactful. It’s kind of a slow creeper, if you will."
Ellison says he wants the installations to get both visitors and scientists thinking about these issues. Back in 2004, researchers tried to mimic the way the HWA kills hemlocks, to see how the ecosystem would respond.
“We took chainsaws and knives and cut rings around the bark and into the wood to cut off the flow of sap,” Ellison explains. “In these two experimental plots, we killed about 2,000 trees in 45 minutes.”
The results are printed on the side of a woodshed. It’s a graph that reads “Lifeline of a Dying Hemlock.” The plummeting red and black lines depict the amount of sap running through a hemlock trunk.
“The graph shows us the difference in sap flow between a tree that we didn't cut and a tree that we did cut,” Ellison says. "It’s just like watching an EKG of someone in the intensive care unit as their heart rate goes down."
This got Ellison thinking about the ethics of his work. “I like to try and use this as a way to talk to my scientific colleagues about how we really have to think about what we are doing to the organisms we study,” he explains.
"We killed these trees to understand how this forest would respond. We learned a lot by doing that. We respected what we're doing and we published our data. That’s how [information] gets out. But we do have an impact on our forests in order to understand this."
One of the last installations on the trail shows the future of this forest: a mossy hemlock stump and next to it, a healthy black birch tree. Ecologists believe birches will one day replace hemlocks here.
The woods will change and it won’t look like a colonial settlement or the hemlocks’ deathbed. But Borden and Ellison hope “Hemlock Hospice” will create a space for visitors to remember the hemlocks long after the exhibit ends.