HVRHS students shown the danger of invasives – and how to fight them

SHARON — A group of students from Housatonic Valley Regional High School (HVRHS) were given a tour of the Northwest Corner’s past and future forests at the Sharon Land Trust’s (SLT) Hamlin Preserve on a chilly November afternoon.

Noted North Canaan environmentalist and photographer Tom Zetterstrom, who recently earned an award for his advocacy, led the group around the property with the intention of demonstrating a living case study in invasive plant management. This was no casual visit — the students were there to prepare for a multi-national environmental education competition called Envirothon.

Envirothon is an annual contest that draws teams from schools and youth organizations across the U.S. and Canada to demonstrate their capacity in addressing environmental issues. The assembled group of aspiring environmentalists, forest managers and outdoor stewards was HVRHS’s team, who meet weekly to learn about the pressing issues facing today’s landscapes and to equip themselves for the upcoming competition.

Team leader David Moran, who is the agriscience and technology education director at HVRHS, said he tries to get the group out in the field as much as possible. “Local experts offer informative mentorship for the students which I think is the best part of the program,” Moran said.

“We’re in a classroom sometimes, though,” he admitted.

Moran has been directing HVRHS’s Envirothon program for 22 years, out of which HVRHS has represented Connecticut in the finals 10 times. “We’ve been to some beautiful places,” he said.

The team is prepping for 2025’s contest, which will be held in Calgary, Alberta, Canada, in July. In order to qualify for the finals, the team must first beat out other Connecticut teams and win the state competition.

Each year is hosted by a different state or province, and centers on a unique theme. This year’s focus is resilient forests, titled “Roots and Resiliency: Fostering Forest Stewardship in a Canopy of Change.”

The flora of the Hamlin Preserve is nothing if not indicative of change. The apex of the tour came when Zetterstrom stopped the group amongst a clearing populated by massive piles of dry brush and several skeletons of trees draped in brown vines. Zetterstrom related that this was the site of a former cedar forest that was completely overcome by invasive bittersweet.

He explained that the site was an example of bittersweet at “full biological potential” — “a monoculture,” as he put it. He also pointed out infestations of brush invasives, such as buckthorn and honeysuckle, that dominate ground-level vegetation.

Zetterstrom recited a quotation from Doug Tallamy, Chief Entomologist at the University of Delaware, twice during the outing: “Succession is dead in invasive zones — it moves to a perpetual tangle of invasive vines.” Succession is the natural progression of species over time in a forest ecosystem. When invasives proliferate unchecked, Tallamy is saying, the only new species allowed to flourish are more invasives.

While an elegy to the forests of the past, and a potent warning of a potential future, the walk also offered signs of hope. Zetterstrom motioned to a thick forest of white pine with interspersed cedars that extended up the hillside past the clearing. The survival of those trees, he said, is due to the efforts of SLT volunteers, who spent long hours cutting, treating, and clearing massive amounts of bittersweet from the former cedar grove.

“The volunteers cut and treated so many vines that we’ve already killed the root system,” Zetterstrom said of the former bittersweet growth that dominated the canopy. Dead vines still hung from the conifers’ limbs, but they will no longer grow.

The Hamlin Preserve is also home to several of Northwest Connecticut’s proudest trees, including an apple tree that was recently declared the state champion of its species.

“It had delicious apples, but what else did it have?” Zetterstrom asked the students. “Bittersweet,” chimed in several voices as Zetterstrom held up a wrist-thick cross section of vine that had been cut from now-dead bittersweet plant that roped through the tree’s limbs.

The apple, though old, will survive for a while longer due to volunteers’ efforts in clearing the vine from the tree. A statuesque American Elm (one of few to survive Dutch elm disease), as well as an unusually large paper birch, also thrive on the Preserve thanks to anti-invasive intervention by SLT and its volunteers.

The students were attentive throughout the tour, asking questions and taking samples of bark and other woody material to bring back to the school. They even wanted to bring back a stump of one of the dead cedar trunks that lay in several piles on the Preserve. Zetterstrom dutifully complied, firing up his chainsaw and cutting off a cross-section as the students (safely distanced) watched on.

SLT Executive Director Carolyn Klocker, who joined the excursion with her daughters, said that it was the students that brought her out that afternoon. “It’s just inspiring to be out with a group of young people who are excited to learn about all this,” she said.