Pine bush thinning and burning may protect its trees as southern beetle expands its range

— Photo from NYSDEC
The pine tree tops at left are brown because of an infestation of southern pine beetles.

ALBANY COUNTY — The southern pine beetle is here but Neil Gifford is not worried — just concerned.

Gifford is the conservation director for the Albany Pine Bush Preserve.

He says the southern pine beetle “is a native beetle that has co-existed with short-leaf and long-leaf pine for centuries, if not millennia, in the southeastern United States.”

The furthest north the beetle’s range went was to Virginia and West Virginia and maybe to the southernmost tip of New Jersey, Gifford told The Enterprise this week.

But, now, because of climate change, the southern pine beetle is in the pine bush preserve.

The preserve has worked with the state’s Department of Environmental Conservation since 2018, Gifford said, placing traps for the beetle in the pine bush. The traps use pheromones, chemicals emitted by the beetles to communicate with one another, and so attract them.

One single beetle was trapped in 2019 — and then nothing. But last fall, around 80 beetles were in each of two traps in the pine bush. The preserve, a globally rare pine barrens, spans more than 3,400 acres.

The DEC put out a release on Friday, calling the beetles “a destructive forest pest” posing a “significant threat” to pine forests, particularly pitch pine like that found in the Albany Pine Bush. The southern pine beetle was first discovered in New York infesting pitch pines on Long Island in 2014, and since then, it has killed hundreds of thousands of trees on Long Island alone, the DEC said.

Gifford, though, makes an important distinction between invasive species and native species. 

He said of the southern pine beetle, “It’s basically, just honestly, doing exactly what we would hope native animals would do in the face of climate change — move and find additional resources to continue to persist.”

Gifford went on, “The bigger ecological story here is the fact that the beetles can damage the pine stands — that is more a symptom of an ecosystem’s health.”

Ecosystems now are not as healthy as they used to be. “It’s the same thing with the Karner,” he said of the endangered blue butterfly that has become a symbol of pine bush preservation.

“Its demise was an indicator that the ecosystem was less healthy,” said Gifford.

Gifford believes that, if forests are properly managed, they can coexist with the beetle just as the pine bush does now with several other native bark beetles.

Thinning the pine bush and doing regular controlled burns are the answer, which is twofold, Gifford said.

Thinning a forest creates more air current, letting air easily travel through. “Think about a cold, blustery day,” said Gifford. “Do you want to be out in the middle of an open field or do you want to be in a dense forest?”

In a dense stand of trees with a closed canopy, chemical pheromones linger and build, said Gifford. “You get a cloud of this building in the forest because the air is not circulating.”

The way the beetles work, he explained, is a few females will initially attack a tree — often a wounded or weakened tree. “And once they find a suitable host, the females release a gathering pheromone … like a cloud of perfume, that will build in a dense stand of trees and attract an awful lot of beetles,” he said.

What happened on Long Island, Gifford said, is that the southern pine beetles, in those dense stands of pitch pine, were highly effective at communicating and attracting other beetles so that entire stands were killed in a single growing season.

The other advantage to thinning and burning is that it reduces the number of trees per acre. “There’s less competition for resources,” said Gifford. Each tree is then able to get more water and be stronger, he said.

A tree’s number-one strategy for getting rid of the beetles is pitching them out, Gifford said. A healthy tree with adequate access to water, he said, produces “a lot more sap to push the beetle out.”

He went on, “The problem in a really dense forest, where the trees are competing for water, is they don’t all have enough water to effectively eliminate the beetles. When you reduce the stand density, you’re giving those trees that are left that much more access to water. And they’re much better at pitching the beetles out.”

So, Gifford concluded, he’s concerned because the southern pine beetle is moving into the northeastern pine barrens where it’s never been before. “The big question mark that we all have is … how the trees in the ecosystem will respond.

But he also said, “We’re not particularly worried because here we have been doing the thinning and burning for years.

He said of the southern pine beetle, “It’s coexisted with the pines in the Southeast for a long time. So, if the pine ecosystems up here are managed appropriately, the beetle should be able to coexist just as the other native park beetles do without decimating the pine trees.”

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