One tree at a time, David Saville has made it his life’s work to bring back the red spruce forests of West Virginia—and maybe help save the species hundreds of miles further north while he’s at it.
Last year, Savill spent weeks climbing peaks like Panther Knob, Dolly Sods and the Top of Allegheny to harvest hundreds of pounds of pinky-sized tree cones. At home in Morgantown, he kiln-dried them and boiled them for seeds. Now they are tiny trees.
Next spring seedlings, which has genetics from the southern end of the tree’s range, will go into the ground in Vermont and New Hampshire. It is hoped that when they start making their cones in 30 years, they will be able to survive in warmer northern climates.
“We expect Mother Nature to move the red spruce north,” Savile said. “We’re just speeding it up.”
He’s one of hundreds of foresters, horticulturists, scientists and researchers working to ensure that species like the red spruce outgrow a climate that’s changing faster than they can keep up. Although such “assisted migration” is increasingly controversial, as the magnitude and rate of temperature increase become clear, it is being considered more frequently.
“The goal,” said Tony D’Amato, a professor of forestry at the University of Vermont who is overseeing the experiment, “is to help them deal with these really unnatural conditions that have no analogues in the past.”
With climate warming, devastation by insects and habitat destruction1 in 6 US tree species outside of Alaska are threatened with extinction, a study released last month found. Among them are the Torrey pine from California, the maple oak from Arkansas, the Franklin tree from Georgia, the American chestnut and the black ash from the East Coast.
These trees have evolved to adapt to the climate in which they originally grew, said Brad St. Clair, a geneticist emeritus who has worked for decades at the Forest Service’s Pacific Northwest Research Station in Corvallis, Oregon. Historically, the rate of tree migration is between 650 and 1,300 feet per year, he said.
“To keep up with climate change, it would have to be about 10 times that,” he said. By the end of the century, mossy, rainy Portland, Oregon, is projected to look more like Redding, California, which is dry and muggy in the summer. “Plant populations won’t be able to keep up.”
After more than 30 years of debate in the US forestry community, numerous trials are now underway to test how well assisted migration works and whether it disrupts existing ecosystems.
Helping tree species move to more hospitable climates, sometimes referred to as managed translocation, simply means planting them in climates to which they are genetically suited. It’s just that their native climate has changed, said Gerald Rehfeldt, a forest geneticist who published some of the first papers on the subject in the 1990s.
While the climate hasn’t changed dramatically yet, projections show it will become a much bigger problem by mid-century, St. Clair said.
“We have to do something now if we want to have any hope of keeping up with this,” he said.
What is natural these days?
The idea of playing God with species by moving them further north than they naturally could on their own over time is controversial. A central belief of the environmental movement is that nature should be left alone as much as possible – human craftsmanship, however well-intentioned, can all too easily go wrong.
“Red flags are going up,” said Forest Service geneticist Jessica Wright, who is planting reforestation test plots on the West Coast. “It’s something that has to be done very carefully. You’re opening a Pandora’s box.”
There are many examples of best intentions going awry. Introduced from China as a popular landscape tree, the tree of heaven has become invasive across much of North America, even releasing a chemical toxic to nearby plants. The glossy cinquefoil is displacing native species in the eastern United States. The Bradford pear, originally imported from Asia in the 1960s, is so invasive that several states have banned its sale.
But an alternative to moving trees to climates to which they are better suited is to allow natural selection.
“It’s okay if you like seeing a lot of dead trees and you like big megafires as a result of those deaths. And if you don’t like the wood or the habitat that went with the forests,” St. Clair said.
Many argue that at the moment there is no such thing as “natural”. Humans have made huge changes in burning fossil fuels since the Industrial Revolution began in the 1750s, said Cuautemoc Sáenz-Romero, a research biologist at the Universidad Michoacán de San Nicolás de Hidalgo in Mexico.
“Forests can’t follow their natural cycles because now we have 420 parts per billion of CO2 in the atmosphere,” he said. “The normal level is 260.”
No longer a fringe idea
The primary forest community increasingly sees assisted migration as a necessary tool as the planet warms.
Wright hopes her test plots of saplings will provide insight into how trees in California, Oregon and Washington will fare by the end of the century. While 80 years is a long time for people, for many it is a blink of an eye tree species.
“We trade space for time,” she said.
Such efforts are aimed at giving trees a chance, not at changing the face of forests. “We’re moving populations within the species’ range,” she said. “It can’t be, ‘Let’s plant Joshua trees in Oregon.'”
In Vermont, D’Amato wants to be clear that no one is talking about replanting entire forests.
“We’re just trying to introduce some of these trees so that in 50 to 100 years we have some seed-producing individuals that are adapted to the changes that can sustain the forest going forward,” he said.
Sometimes the job is not to move, but simply to preserve species until they can be re-introduced to a new, more favorable home. An international network of arboretums act as lifeboats for endangered species.
In Chicago, the Morton Arboretum planted specimens of two endangered southern oak species, the maple oak and the Georgia oak, in case they become even rarer in their current homes due to rising temperatures.
“We’re trying to be proactive in the sense that we want to plant species that are well-adapted to these future climate change scenarios,” said Silvia Alvarez-Claire, the arboretum’s director of global tree conservation.
Without intervention, a species can slowly move north a few hundred feet per generation.
“It’s happening so fast now that trees don’t even have a generation or two to adapt,” she said.
While arborists in the United States are cautiously testing these ideas, in Canada’s westernmost province, migration assistance is now the law.
In April, the province of British Columbia made it mandatory to replant trees on the province’s logged lands to suit the climate. Previously, seedlings had to come from one common area. Now they come from 250 miles to the south.
The province transplants 300 million seedlings a year on cleared land.
“You want to get your seed from where it’s 3.8 degrees warmer now, because we have to recognize that there’s already been 2.7 degrees of climate change in the last 80 years,” said Greg O’Neill, a spokesman for the province climate change adaptation scientist.
Saving butterflies by moving trees
Not only trees are at stake, but also entire ecosystems. Take your favorite monarch butterfly.
Over millions of years, the iconic insects have made an epic 2,500-mile journey from Canada to Mexico. There they winter in the mountain forests of Abies religiosa, which are called oyamel in Spanish and sacred fir in English.
Today, trees at low elevations are struggling.
“The rainy season now starts a month late, and to make matters worse, it ends a month early,” Saenz-Romero said. Partly because of this habitat loss, the monarch was added to the International Union for Conservation of Nature’s “red list” of threatened species this summer.
A pilot project in Mexico trying to help. At the Monarch Butterfly Biosphere Reserve, a UNESCO World Heritage Site 80 miles west of Mexico City, Sáenz-Romero plants sacred fir seedlings higher up the sides of dormant volcanoes, where it’s cooler. He wants to see if the trees and the monarchs that depend on them can survive better there.
His research found that moving trees 1,300 feet uphill — equivalent to a 3.6 degree cooler environment — kept them healthy.
The question of whether monarchs will move to new forests remains unanswered.
“We hope so,” Saenz-Romero said. “We pray.”
2022 USA Today. Distributed by Tribune Content Agency, LLC.
Citation: Trees can’t outrun climate change. Should people give them a ride? (2022, September 21) Retrieved September 21, 2022, from https://phys.org/news/2022-09-trees-outrun-climate-humans.html
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