Island naturalists continue invasive beetle battle

Concerned and curious about the risks that southern pine beetles and nematodes pose to Vineyard forests, members of planning and conservation groups hosted experts from the U.S. Forest Service, Harvard University and other groups during a Friday meeting of the Martha’s Vineyard Commission (MVC) Climate Action Task Force.

Experts agreed that more action is needed to fight the beetles — which have infested West Chop Woods and Manuel F. Correllus State Forest — in order to protect Island pitch pines.

They also said that microscopic nematodes will continue to be a scourge on beech trees.

According to Dr. David Foster of Harvard Forest, decimation of beech trees is a likely outcome. To respond and adapt to these threats, including the risk of wildfires, experts recommended that Vineyard forest managers consider reducing pitch pine density in beetle-infested areas, removing pitch pine overstories, and conducting prescribed fires.

Pine beetles were a major gripe of Vineyard land managers and conservators during Friday’s discussion. The beetles were confirmed on-Island last fall, and have been more populous in northern states since migrating from southern states around the mid-2010s. These invasives are known to quickly chew through, destroy, and reproduce in vast quantities of pine trees.

In the the State Forest last August through October, the beetles were found in pitch pine trees in three areas, impacting about a dozen acres. The Massachusetts Department of Conservation & Recreation (DCR) responded by cutting down 100 infected trees, and removing 100 additional trees to form a buffer zone in order to prevent further contamination. “It looks like for the foreseeable future, it’s just something we’re going to be dealing with,” said Connor Laffey, forest & park supervisor at DCR.

Sheriff’s Meadow, which owns 2,000 acres on-Island, is currently responding to two infestations at its West Chop Woods property. Adam Moore, the Executive Director of Sheriff’s Meadow, said that two trees were cut down last week, and that a three-tree infestation will be cut down next week.

“They are like an angel of death when they come into the forest and get a head of steam going. It’s humbling, and we ought to be humble in front of this force of nature,” Moore said.

His humility largely comes from seeing the beetles devastate Phillips Preserve, a Sheriff’s Meadow property in Tisbury. “Last summer, we saw them at about half an acre,” Moore said. “And they wiped us out over there. You can drive down Army Road now and see the clearing they have, and if you look towards the north, all the treetops are either barren or red. And the red ones are the ones that are in the process of dying.”

The beetles consume at an astounding rate, Moore said. “They were just moving 10 feet every day, and one night, they jumped 100 feet, and we just said, ‘Uncle!'”

To fight beetles going forward, Moore said that Sheriff’s Meadow is taking inventories of trees on four properties of concern, and will complete a forest management plan. In the next couple of years, Moore says that Sheriff’s Meadow plans to thin pitch pines in affected areas. In the long term, the pitch pine populations can be sustained partly by ensuring that direct sunlight reaches the bare soil. The forest management plan will be reviewed by DCR, as will any plans to remove trees.

Kevin Dodds, a forest entomologist with the U.S. Forest Service, commiserated with the Vineyarders on Friday, sharing his experiences fighting and studying southern pine beetles on Long Island. The beetles destroyed 5,000 acres there from 2014 to 2023. “I think of it as an … insect that’s not really to be toyed with,” Dodds said.

According to Dodds, areas highly dense with pines are most vulnerable. But less dense areas should not be assumed safe. He added that lessons could be learned from Long Island’s case, and that the Vineyard’s forest managers should consider whether they want to keep pitch pines present in vulnerable areas moving forward. This is particularly relevant in areas where pitch pines make up a forest’s overstory. “You have this giant mismatch between what the forest is in the overstory versus the understory,” Dodds posed. “And you go into these forests and there is absolutely no pitch pine in the understory … and so the southern pine beetle comes in, kills the overstory pitch pine, and that results in the complete conversion of forest type. And so, in some areas that may be OK. But if you want to maintain pitch pine … this is the time to really put in some restoration treatment.”

That restoration, Dobbs said, could involve overstory removal, and managers should consider prescribed fire and understory treatments.

Dobbs added that as climate change causes milder winters on-Island, the beetles may no longer be stopped by subzero temperatures. “Five [degrees] Fahrenheit below gets us 80 percent mortality of the brood in trees,” he said. “Once you have the beetle there and there’s [a] habitat, unless we really have the winter, we’re just going to continue to see damage.”

While the beetles infest pitch pine, microscopic nematode worms have been bad news for the Vineyard’s beech trees. Beech leaf disease occurs when nematodes damage the leaf buds, and can be fatal if sustained. Dr. Foster told the Vineyarders that decimation of beech trees is a likely outcome. “The interesting thing is, it’s happening so quickly and so pervasively, and there’s essentially nothing to be done, that our attitude is [to] stand back and just allow it to happen,” he said.

Moore said that Sheriff’s Meadow is taking a passive approach. “We’re sad to see what seems to be happening to many of the beeches here … we don’t know what to do. We don’t understand the disease very well. We don’t want to do anything chemical in the forest, and we don’t want to go in and cut the trees down and take any active steps,” he said.

Preventing wildfires was discussed more briefly on Friday, though multiple speakers were receptive to a follow-up meeting to focus on the topic. David Celino, Chief Fire Warden for DCR’s Bureau of Fire and Forestry, shared that 44 wildfires have been recorded on the Vineyard in the last five years. The largest of these was across more-than two acres; most were under one acre. At least one of the fires was a lightning strike, Celino said, but the majority were caused by humans.

Moore stated that dense pitch pine forests and scrub oak barrens could pose significant fire risks. Scrub oak barrens, Moore added, are a lesser concern, as they are closely managed. Oak brush forests generally pose a low risk of fire, Moore said.

According to Foster, many threats to Vineyard forests are linked to a larger problem.

“I think the biggest threat to the Vineyard is land use,” he said. “We are regularly making our natural forest and our natural environment smaller … we are deforesting, we are clearing areas.”

“The forests of the Vineyard are not being managed very actively, “ Foster added.

Christopher Neill, Senior Scientist at Woodwell Climate Research Center, is concerned about what might happen when threats overlap. “The thing that keeps me up at night in terms of forest is these interacting stresses,” Neill said. “What will happen when beech leaf disease hits a forest that is already under stress from other factors, including … interacting with drought?”

Neill highlighted the Natural Neighbors program as one way for concerned residents to make a difference. The program, run by Vineyard-based BiodiversityWorks, helps residents and residential groups plan habitats on their private properties. That amounts to a lot of land in total. “Collectively, it’s a very big area that could contribute to all the goals we’ve been talking about,” Neill said.

Though speakers agreed that many forested areas on-Island are vulnerable, Foster said that the Vineyard’s forests are unique and worth the attention. “They’re not like forests in most other places. They’re not even like forests in coastal areas,” he said.

Foster added that New England lacks old-growth forests, and that some areas on the Vineyard, such as Ripley’s Preserve, are just about to reach that status. “So, allowing that to develop would be a very important kind of natural process, and give real opportunity on the Vineyard,” he said, also stating that some Vineyard pitch pine forests have trees aged 175–200 years old.

“Our forests on the Vineyard are at the greatest extent and the oldest age that they have been for 300 years,” Foster said.