Up Rooted
Mother Jones|November/December 2021
Forests have always migrated to survive. But now they need our help to outrun climate catastrophe.
Por Lauren Markham

I drove to Oregon because I wanted to see the future. Our rapidly changing climate vexes me, keeps me up at night—perhaps you’ve felt this, too—and recently I’d become particularly preoccupied with trees. In California, where I live, climate change helped kill nearly 62 million trees in 2016 alone, and last year, 4.2 million acres of our state burned. I wanted to know what was in store for our forests and, because we humans rely on them for so much— for clean air, for carbon sequestration, for biodiversity, for habitat, for lumber and money, for joy—what was in store for us.

I’d read about a group of scientists who were not only studying the calamities befalling our forests but also working to help the trees migrate in advance of coming doom. So in May, I headed to a 3-and-a-half-acre stand of roughly 1,000 Douglas firs at a US Forest Service nursery outside of Medford. The grove was situated in a wide valley in the southwestern corner of the state, nestled between the Cascades to the east and the Coast Range to the west. Brad St. Clair, a Forest Service scientist who has studied the genetic adaptation of trees for more than two decades, met me by the road. He’s short and rugged, as if built for adventuring and tending to the lives of trees, and he arrived in a souped-up Sprinter van loaded with an armory of outdoor gear. In 2009, he and his team planted this and eight other stands of firs after they’d gathered seeds from 60 tree populations all over Washington, Oregon, and California and grown them into seedlings in a greenhouse. The seeds were sourced from as high as 5,400 feet in the Sierras and as low as the coast, from Mendocino County, California, all the way north to Central Washington, and were planted in intermixed clusters at each of the nine sites to see how they would fare in a hotter, drier climate than the ones they’d come from. In other words, to see if they’d make it in the future.

Douglas fir, a tall, narrow-trunked evergreen often dragged indoors for Christmas, is a favorite of foresters and logging companies because of its combination of strength, fast growth, and pliability. It can also withstand a change in climate of about 4 degrees Fahrenheit without much trouble. But global average temperatures have already risen by almost 3 degrees since the 1900s, and all models predict average temperatures to blow through the 4-degree threshold in the next several decades, perhaps rising above 7 degrees by the end of the century.

In the wide, flat expanse of the nursery, the firs were rimmed by fallow land on all sides. St. Clair instructed me to put on safety glasses, and then ducked down, pushed aside the outermost branches, and slipped into the trees. I followed him. Within two steps, there we were in a veritable, dense forest, as if an enchanted wardrobe had been pulled open to reveal a world transformed. On the periphery it had been hot, but here, as we moved through the dapple, it was cool and fragrant with pine.

A sign mounted on a pvc pipe marked the provenance of the cluster of trees we stood beneath. They came, St. Clair explained, from the Oregon Siskiyou, a dry zone at only slightly higher elevation than where we were today. This is why they were doing so well: Their native climate wasn’t so different from Medford’s. As we moved on, the trees, while still lush and full, grew shorter. Because this next batch was from up in the Cascades, he pointed out, at an elevation far higher than where we stood, the trees were somewhat stunted in this new habitat and couldn’t grow as tall. We kept walking, and after a while the trees grew taller again, looming three times my height before breaking into sky. These trees also came from climates that were dry like Medford, and so found here a happy home—at least for now.

We ducked and trudged through the lower thickets of the healthy trees until we suddenly emerged from the woods onto what I can only describe as an arboreal apocalypse—an open tangle of dead branches, brown and brittle, like an upright graveyard. These ill-fated trees, St. Clair said, had come from the Oregon coast, where it is far wetter. While they’d done okay in the first three years of the study, they just couldn’t make it in the long term. “As the climate warms,” St. Clair said, looking around and pointing up to a dead fir with his walking stick, “you’re going to see more of this.”

The future of forests is a grim one—too grim for some of us to bear. By 2030, 75 percent of redwoods will disappear from some of their coastal California habitats. In some climate scenarios, almost none of the namesake species in Joshua Tree National Park will exist. Sea level change is creating ghost forests all along the Eastern Seaboard— already, less than a third of New Jersey’s Atlantic white cedar habitat remains.

Like humans, forests have always migrated for their survival, with new trees growing in more hospitable directions and older trees dying where they are no longer best suited to live. The problem now is that they simply can’t move fast enough. The average forest migrates at a rate of roughly 1,640 feet each year, but to outrun climate change, it must move approximately 9,800 to 16,000 feet—up to 10 times as fast. And in most habitats, the impact of highways, suburban sprawl, and megafarms prevents forests from expanding much at all. Forests simply cannot escape climate change by themselves.

Back in 1992, forest geneticists F. Thomas Ledig and J.H. Kitzmiller coined the term “assisted species migration” in a seminal study in the journal Forest Ecology and Management. Since then, hundreds of biologists and geneticists like St. Clair have been studying how best to move forests in advance of their looming destruction. To do so requires a complex set of mapping and experiments—understanding, for instance, what climate trees are best suited to grow in, what region will most closely resemble that same climate in, say, 50 years, and what adaptations best ensure that a tree will take root and flourish, build symbiosis with the soil fungi, and not end up a mere matchstick awaiting the next megafire.

St. Clair is something of an assisted migration evangelist, a firm believer that we need to move tree populations, and fast, if we want to keep apace. But due to bureaucratic logjams and a fervent commitment to planting native species, there’s very little assisted migration in the United States— unlike in Canada, where the practice has been adopted with more urgency in recent years. St. Clair and other Forest Service scientists are working to transform assisted migration from a mere research subject to a standard management strategy in our vast, imperiled public lands.

We finished our walk through St. Clair’s baby forest, making our way back to the cars along its outer edges. “The future is terrifying,” I told him. He understood what I meant, he said.

During the talks he gives about his research, he likes to show an image from Lewis Carroll’s Through the Looking-Glass, in which the Red Queen charges forward with her crown and sturdy scepter, pulling frenzied Alice along in her wake. He had the slide printed out and handed it to me as we walked. “Now, here, you see,” the Red Queen says to Alice, “it takes all the running you can do, to keep in the same place.”

“So that’s what we gotta do,” he told me, pointing to the Red Queen. “We gotta run.”

WHILE ASSISTED migration is a relatively new concept, the movement of forests is as old as trees themselves. Since they first evolved, trees have been shifting north and south, east and west, up and down in elevation as the climate has changed. Forests outran the frost as an ice age set in, and as the ice began melting, they darted back the other way, traversing mountain ranges and unfurling themselves across continents— moving, sentiently, toward climatic conditions that suited their ability to grow and produce the trees of the future.

Of course, while forests move, individual trees can’t. “They are stuck where they are,” explained Jessica Wright, a senior Forest Service scientist based in Davis, California, who studies conservation genetics. Trees must try to survive whatever environment they land in. And yet, Peter Wohlleben writes in The Hidden Life of Trees, while every tree has to stay put, “it can reproduce, and in that brief moment when the tree embryos are still packed into seeds, they are free.” The seed sets forth, as Zach St. George chronicles in The Journeys of Trees, carried by the wind or in the belly of a blue jay or stuffed in the cheek of a squirrel, toward its destiny. If it is among the luckiest, it will find a hospitable home and carry the forest forward. Because seeds will only take root in areas suited to their growth, forests tend to move in the direction of their future survival.

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