• Greater Yellowstone Ecosystem land managers brace for the second climate-driven epidemic this century and fear for the survival of the remaining old-growth conifers.
By Mike Koshmrl, WyoFile.com
Vegetation ecologists monitoring the latest mountain pine beetle epidemic fear for the survival of the Teton Range’s remaining ancient whitebark pine stands.
A keystone species that gained Endangered Species Act protections early this year, whitebark pines were hit hard by a plague of mountain pine beetles that spanned from 2004 to 2012.
A cold snap ended that wave, giving the region’s embattled whitebark pine a temporary reprieve. Four years ago, however, scientists monitoring the gnarled high-elevation conifers started to see a larger concentration of “brood trees” harboring increasing numbers of the bark-boring insects.
“It’s just another beetle epidemic happening because they are not being slowed down by cold falls and springs — like they naturally were before,” said Nancy Bockino, a Northern Rockies Conservation Cooperative whitebark pine field ecologist who has long monitored the species in Grand Teton National Park. “And it’s getting worse.”
Bockino wrote about the ongoing infestation in a publication called Nutcracker Notes, which is produced by the Whitebark Pine Ecosystem Foundation. Her paper was ominously titled — “Here we go again: The mountain pine beetle is killing our remaining old whitebark” — and in the article she referred to the repeat epidemic as a “grave situation.”
“First,” Bockino wrote, “the loss of any of the few remaining cone-bearing whitebark is a significant setback for conservation and restoration.”
Moreover, she added, “a second epidemic may result in so few whitebark pine that the delicate and obligate mutualism between the tree and the Clark’s Nutcracker could collapse.”
The Clark’s Nutcracker is a species of jay that whitebark pine depends upon to disperse its seeds. But dependency in the relationship is not entirely mutual: nutcrackers can subsist on other pine seeds when whitebark seed stocks are poor. In its rule listing whitebark pine as a threatened species, the U.S. Fish and Wildlife Service wrote that climate change could negatively affect nutcracker populations, potentially exacerbating whitebark decline.
The Tetons and Wind River Range have historically been bright spots for whitebark pine conservation within the Greater Yellowstone Ecosystem.
Whitebark pine seeds are a major food source for grizzly bears, and during the height of the 2004-to-2012 epidemic, beetle-killed whitebark monitored by the Interagency Grizzly Bear Study Team amounted to 76% of all the trees being monitored. A higher percentage survived in Grand Teton National Park, however.
Bockino and others surveyed Teton Range whitebark pine in 2022 to try to get a grip on the scope of the epidemic. They found that 54% of the overstory was dead from pine beetles. Just more than a third of those dead trees — 35% — showed signs of beetle attack between 2019 and 2022.
The reemergent threat from mountain pine beetles is also hitting whitebark hard in other southern swaths of the Greater Yellowstone Ecosystem. Increasing beetle activity has been observed in the Wyoming, Salt River and Wind River Ranges and at sites on the Caribou-Targhee National Forest, according to Bockino.
Unlike the nonnative fungus blister rust — another threat to whitebark pine persistence — mountain pine beetles are a native species that the long-lived tree evolved alongside. What’s changed and made pine beetles an existential threat are the survival rates of the bark-boring insect. Extreme cold in the spring and fall can knock back beetle populations, but the subzero temperatures needed for beetle die-offs are happening evermore infrequently as the climate warms.
In the rule establishing whitebark pine as “threatened” under the ESA, the Fish and Wildlife Service used 60-year intervals between outbreaks for scenarios modeling how the species would fare. “Unfortunately,” Bockino wrote in her article, that interval is “in contrast to what is happening in the GYE,” where there have now been two epidemics in less than 20 years.
“Real-time management action is urgent,” she wrote. “The prioritization of retaining every possible existing seed tree at all costs is unquestionable.”
Grand Teton National Park vegetation managers aren’t standing idly by.
“We know that without intervention, the persistence of the species is in jeopardy,” said Laura Jones, the park’s chief of vegetation management. “We’ve been gearing up for restoration actions and we’ve continued doing work protecting trees. And we do have some new funding sources.”
Grand Teton crews will begin planting 4,000 whitebark pine seedlings in the fall of 2025, Jones said. And there are ongoing efforts, she said, to install beetle traps at the known blister rust-resistant whitebark stands.
In healthy stands of whitebark pine, Bockino and others have also continued hanging pouches of verbenone, a pheromone that signals to the beetles the trees are already occupied. There was talk of stopping the labor-intensive pouch-hanging efforts during the lull between beetle epidemics.
“Right about that time, I was like, ‘Wait a minute,’” Bockino said. “We were having this massive outbreak on Static Divide, with hundreds of trees getting killed over there. That was 2019. It just kept growing.”
Bockino has even gone so far as to ski up into the Tetons in the winter to strategically strip the bark off of beetle-infected trees. That fatally exposes the brooding insects to the sun and the cold, Bockino said.
At least one ecologist is committed to doing whatever it takes to keep old, gnarled whitebarks that remain alive.
“Think about it. A 700-year-old whitebark pine is beyond precious,” Bockino said. “That’s a long freaking time. Personally, I’m trying to do everything I can to save those.”
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