Overheard at National Geographic Listen as writer Craig Welch recounts the search in “The Tree at the End of the World,” in season three of our podcast.
Seven trees sprout on a hillside near the southern tip of South America, above the treacherous swirl of spray where the Pacific Ocean meets the Atlantic.
It’s not an impressive bunch—just a tangle of gnarled limbs and silver bark hidden by reedy grass. A few are dead. None reaches higher than my thigh. The living bend and curl their way a dozen feet across the ground, like soldiers clawing through battlefield mud. Furious winds have driven the trunks completely horizontal.
It’s hard to square these scraggly specimens with the exceptional lengths we’ve gone to in order to find them. We’ve flown across oceans; chugged 32 hours by ferry; motored 10 hours more on a wooden charter boat captained by a sailor who confessed mid-journey that he’d never navigated this deadly stretch of sea. Only then did we reach our destination—Isla Hornos, the island where Cape Horn is located, the last land in Tierra del Fuego. There we hiked through gales that knocked us down, slipped on penguin guano, and vanished to our armpits in thickets of barberry.
We’ve come all this way to map a border no scientist has mapped before. We’ve come to find Earth’s southernmost tree.
“This is it,” says Brian Buma, a forest ecologist at the University of Colorado Denver. He’s draped head to toe in orange and black rain gear. Straddling hummocks, he rechecks his compass and mutters, “Cool.”
Few things in the natural world can be identified as the true end, the last of a kind, the edge, Buma tells me. He pulls a measuring tape from his daypack and starts appraising one recumbent trunk, a few inches south of the rest.
“It strikes me that we should know where these things are,” he says.
In the 21st century it can seem as if there are no places we’ve not surveyed down to the last inch. We take selfies on the world’s tallest mountain, pilot submarines to the oceans’ deepest trench, explore the planet’s driest deserts. But we’ve never identified—at least not correctly—the final stands of trees at the top or bottom of the world.
Now forests are on the move. As the climate warms, tree lines are moving higher up mountains, and tree species also are extending their ranges toward higher latitudes. As trees move, ecosystems change. In Alaska longer growing seasons now let willows get so big they poke through snow in winter. That has drawn moose and snowshoe hares from the Brooks Range all the way to the Arctic Ocean. The Arctic and parts of Antarctica are among the fastest warming regions on Earth.
But most of what we know about these grand ecological shifts comes from research north of the Equator. The global south, Buma says, is often neglected.
Thumbing through old botany books and explorers’ journals, he saw an opportunity: They contained a bewildering assortment of claims for the whereabouts of the global south’s last woods. If he could find the southernmost tree, it could become the focal point of a living laboratory that scientists could visit for years to come. They could monitor soil warmth and tree growth. They could study the animals living in this ecosystem on the edge. Over time they could track whether that edge was moving.
But first Buma would have to find the tree. And finding anything in the archipelago that brushed back Charles Darwin and nearly broke Captain Bligh wouldn’t be a walk in the woods. Just getting near it would be hard enough.
Buma prefers science that mixes sleuthing with adrenaline, ideally in hard-to-reach forests, in miserable conditions. Once, in Alaska’s Glacier Bay National Park, he kayaked icy fjords in pouring rain and pawed through head-high shrubs thick with brown bears—all just to locate some minuscule research plots no bigger than couch cushions. They’d been set up in 1916 by a botanist named William Skinner Cooper. The plots had become overgrown and were lost to science until Buma pulled Cooper’s hand-drawn maps from dusty archives. Now they provide a century-long record of how plants take over ground uncovered by retreating glaciers.
Buma recounts that adventure from a seat on the cargo ferry Yaghan. Along with photographer Ian Teh and a collection of old trucks and bed frames, we’re chugging through the Strait of Magellan beneath slate skies on a January afternoon. Outside, ice-blue glaciers spill down the flanks of the southern Andes. Macaroni penguins crowd boulders near shore. We’re on a day-and-a-half run from Punta Arenas to Puerto Williams, Chile, South America’s southernmost city. There we’ll rendezvous with a smaller boat.
Tall and sunburned, in a flannel shirt and too-long canvas work pants, Buma is in high spirits—a detective off to untangle a new mystery. With a National Geographic Society grant, he and Chilean ecologist Ricardo Rozzi have assembled a crew that hopes to study the south’s terminal forest. One researcher will try to record bats. Two others will scale trees to study the canopy. An archaeologist plans to sift through sands for signs of early human settlement. And a small team will help Buma spot his tree.
Buma opens a sketchbook to a drawing of our destination. In the austral twilight it resembles a pirate map. Buma confesses he’d briefly considered hunting for the planet’s northernmost tree—most likely a larch in central Siberia—but that’s too large a region to search. He wanted to be certain, Buma says, “we could find an answer and be sure we were right.”
In the Southern Hemisphere there’s far less ground. Antarctica was forested tens of millions of years ago during the Eocene epoch, when the planet was warmer, but no trees live there now. The ocean around it is dotted with islands, some of which sprout rushes, forbs, and grasses, but they too lack trees. The islands have been surveyed repeatedly since James Cook pronounced South Georgia island treeless in 1775.
Scouring the internet, Buma found claims literally all over the map. One website suggested the world’s southernmost tree was on Navarino Island, where Puerto Williams is, at least 45 miles north of Cape Horn. Another put it on Hoste Island, 35 miles northwest of the cape. A journal article from the 1840s based on a dispatch from botanist Joseph Dalton Hooker, who sailed with H.M.S. Erebus and H.M.S. Terror, concluded confidently: “Hermite Island may be considered the most southerly spot on the globe where any thing like arborescent vegetation is to be found.”
But Hooker never visited the island just south of Hermite, the one in Buma’s sketchbook: Isla Hornos. At the time of our journey, Wikipedia dubbed it “entirely treeless.” Why would there be trees on Hermite but not on Isla Hornos, a few miles away? Buma wondered.
When he made his case to Rozzi, the Chilean was enthusiastic. Rozzi “was like, ‘Oh yeah, I’ve been there,’ ” Buma recalls. “ ‘There are trees.’ ”
In Puerto Williams, where Rozzi oversees a research station operated by the University of Magallanes, we load our gear onto the Oveja Negra—Black Sheep. The 65-foot cruiser fashioned from cypress is piloted by Rozzi’s frenetic, wild-haired cousin Ezio Firmani, a former chef. Soon we’re cutting south through the Beagle Channel, named for Darwin’s ship. The captain bubbles with excitement—“I’ve never rounded the cape!” he shouts. My stomach groans.
Cape Horn is a massive prow, a knobby headland that plunges roughly 1,300 feet to the sea from the southernmost flank of Isla Hornos. South of there lies a band of ocean that stretches uninterrupted around the planet. Furious westerlies drive the sea surface into giant rollers called graybeards. When those huge waves hit the shallow continental shelf, they produce some of the planet’s most menacing seas. Now and then, icebergs wander in on foaming waters.
For centuries sailors have died “rounding the Horn,” especially moving east to west against the winds. In 1788, before his crew’s infamous mutiny, William Bligh of H.M.S. Bounty tried for a month and failed to negotiate this turn. In 1832 “great black clouds” unleashed “extreme violence” and beat back Darwin.
As we head for the cape, Buma opens his notebook to a sketch of the promontory. The most southern spot where his tree could be is there, springing from a ledge hundreds of feet up. That’s why Buma brought ropes, climbing gear, and John Harley, a seasoned mountaineer. Harley’s prepared to lead us to it, if necessary. “It could be fun,” Buma says. I’m not sure I agree.
Ten hours from Puerto Williams, the rain comes out of suddenly darkening skies. The captain is nervous. A rager is on its way, but we’re finally off the east flank of Isla Hornos. While Firmani considers ducking into a sheltered bay, Buma tells us to get ready. If we don’t make land now, we could be stuck on board for days.
An hour later, backpacks stuffed, we file into small inflatable boats and motor to a shallow beach below a bluff. This is not terra incognita: After climbing 160 makeshift steps, we reach a short boardwalk that leads to an old chapel and a lighthouse staffed by a Chilean Navy petty officer who lives here with his family. A few steps beyond is a metal albatross, a memorial to those who’ve died at sea. On clear mornings a few months a year, cruise ship passengers come to visit. Most stay an hour or less.
None venture where we’re headed. The Chilean government keeps the bulk of this island off-limits. Aside from a select few research teams, virtually no one has ventured beyond this soggy sliver in half a century.
Isla Hornos, at roughly 10 square miles, is shaped a bit like a beetle. A prominent ridge runs north to south, ending in a horseshoe-shaped bay. The western arm of the horseshoe rises to the top of the cape headwall. The other curls east to the lighthouse. By late afternoon we’re ducking into the wind and trudging uphill in gum boots along that eastern flank, taking a meandering three-mile route west.
At first the walking is easy. But as the land rises, the grass gives way to gnarled, head-high shrubs of holly-leaved barberry and prickly heath. Dense witch-fingered branches make passing between them almost impossible. So we step onto the brush itself.
Moving gingerly, we lurch from one tangle of boughs to another. Over time we rise higher up the shrubs, to keep branches from snapping against our cheeks. I travel hundreds of feet this way, boots never touching ground. Occasionally one foot plunges past waxy leaves to my shin, as if breaking through a snowbridge across a crevasse. A few times I fall nearly to my waist.
We reach a wind-scarred plateau. My rippling jacket sounds like a roaring engine against the howling gusts. We have to shout to be heard. Teh, the photographer, gets blown off his feet. It has taken an hour to move less than a mile.
Starting down the west side, we step still higher into the shrubs. Eventually we’re crunching delicately across the very tops of the barberry. It’s not clear if the ground is five feet below or 15. I crash through branches to my throat and have to wait for Teh to pull me free.
At sea level the brush opens enough for us to glimpse sharp ditches, most of them thigh deep, slopped with what we assume is mud. Then we hear a yelp, and someone shouts, “Penguins!” Magellanic penguins have tunneled beneath the brush and are racing underfoot through poop-streaked channels to their colonies.
Finally we hit a wide meadow. Setting up camp, I spy Buma staring west, up a barely visible slope, toward canopies branching above silver bark—the planet’s southernmost woods.
Every day for the next 10, scientists emerge from our half dozen tents and scatter. A Texas researcher scours thin streams for insects. A Chilean ornithologist uses fine nets to catch finches and snipes. Buma, Harley, and Andrés Holz, a Chilean-born forest ecologist from Portland State University, tramp over spongy bogs and mounded cushion plants, looking for trees.
It’s not as straightforward as it sounds. There is no widely accepted scientific definition of a tree. One U.S. National Park Service website, for example, claims trees generally are at least 20 feet tall. But that excludes many varieties—some magnolias and junipers, for example—that most people consider trees. Buma’s team uses a more intuitive definition: A tree is a perennial plant with a single woody trunk and few or no low branches—whereas shrubs have multiple trunks and low branches.
On Isla Hornos the researchers identify three species: a rare winter’s bark and two common southern beeches. Elsewhere, these evergreens rise 65 feet. Here, those protected from wind may reach 30 feet. Most, though, do not. Entire stands aren’t much taller than I am.
These dwarf forests are scattered in patches beneath a ridgeline southwest of our camp. After days spent exploring their perimeter, it’s clear that locating the southernmost individual won’t be easy. If it sprouts from the cape headland, we’ll need clear skies to scan the wall—then winds slow enough to climb up or rappel down it. But this is one of the hemisphere’s stormiest places.
The last tree also could be at the forest’s edge. But it’s more likely to live off alone or in a small cluster, and we may have to comb the ground to see it. A lone tree wouldn’t stay vertical for long.
During our stay, the wind gusts to 75 knots—the bottom of the hurricane scale. It shreds one tent and nearly blows another into the sea. We dry clothes on our back by “stationary sailing”—spreading arms and legs and facing the breeze.
We tackle tasks based on weather windows. One overcast afternoon we venture into a stubby grove to gather data. The canopy is so thick and short, we drop to our knees and crawl. Inside we find a mat of electric green mosses and lichens. Above, each tree is bent and bowed in squat spirals like coiled springs. It feels like a world created by J.R.R. Tolkien and compressed from above by a giant hand.
Holz is surprised by the island’s lushness. Coring several trunks, he finds their rings nearly white, a sign of explosive growth. “These are very happy trees,” Holz says—not what he’d expected from such harsh conditions.
When the mist finally lifts one morning, we hike up the cape headland and peer straight down over the cliff. We scan the glistening ledges and crevices for trunks and saplings. We see nothing, but the angle makes it impossible to rule out arborescent vegetation.
So, more than a week into our stay, on the first sunny dawn, we radio the Oveja Negra. After piling again into inflatable dinghies and clambering back aboard, we putter near the cape for the first time. Buma, excited by the prospect of surveying the last tree while dangling from a rope above the roughest seas on Earth, still hopes his quarry is here. I do not.
We bob in swells a few hundred yards east, scoping the rock from the bow. Even from here I can see the breakers smashing below the face. Behind me, Buma sways gently, binoculars up. He still sees no trees.
“Way at the top—that’s all grass?” Harley shouts.
“Just a lot of grass,” Buma confirms. He turns to me. “But we haven’t looked at it all yet.”
To do that, we’ll have to round the Horn ourselves. Firmani, the captain, prepares to make the treacherous run. In the distance we see whitecaps building. We face the waves and slam through. Firmani, wild-eyed, begins to hoot. The winds pick up, and the boat begins to shimmy. Someone scrambles below deck and gets sick.
Within minutes Firmani turns around. We’ve seen what we needed. He’s eager to pilot us back to smoother waters. Above, the rock’s wet ledges are draped with vegetation. But it’s clear there is no tree. To my relief, the carabiners and ropes Harley hauled halfway around the world won’t be needed.
Back on land, Holz and Buma resume their search in earnest. They march a grid pattern along the slope behind the headwall.
Two days later, Buma finds his tree: a snarl of branches poking through clumpy tussock grass. He checks his GPS device. While I stand next to the tree, he walks another grid and finds the next closest one, 17 meters, or 56 feet, to the north. Using me as a marker, he takes readings from both an analog and a digital compass.
Buma walks back, and he and Holz dig in the grass. Instead of a single tree, they count a group of seven, only some of which are alive. The scientists circle and start chattering.
“We’re on a northeast-facing slope, which is probably the best place to be a tree here,” Buma says. Holz adds, “It’s getting the sunlight and a bit of shelter from the wind.”
The southernmost tree is a Nothofagus betuloides, a Magellan’s beech, a type of tree first collected by Captain Cook’s team. Tree rings place its age at 41 years. Its diameter is just under five centimeters, or two inches, and it stands just under two feet high. From there it bends sideways and grows through the grass.
It’s no sprawling oak, but Buma is pleased. “This is absolutely amazing,” he says.
Aboard the Oveja Negra a few days later, we cut back across a placid Beagle Channel, guided for a spell by dusky dolphins. After 11 days of pounding wind and rain and squeezing three of us into a two-person tent, I’m ready for a beer and a hot shower. Buma is still giddy. He and Holz have made history. Their work has established a scientific baseline to measure forest migration. It’s also just kind of cool.
How much has this place changed as the planet has warmed? We can’t say for sure. But Buma and Rozzi will track what comes next. Will it look different in 20 years? Will this tundra-like landscape become one rich forest? Will winds altered by a shifting climate move the forest’s edge? Might birds one day ferry seeds to the Diego Ramírez Islands, 65 miles southwest, letting trees take root in places that are now treeless?
Climate change can seem abstract, Buma says, but even schoolkids can understand this process. If he can show them a speck on Google Earth that contains this southernmost tree, it will become more tangible and meaningful.
“The idea has always been, let’s find a point, a physical point that people can see, that marks the edge,” Buma says. Then we can watch as the planet moves beyond it.
Senior writer Craig Welch wrote the May 2021 cover story on whale culture. Ian Teh is a Pulitzer Center grantee examining the impact of development and climate change on China’s Yellow River.
This story appears in the June 2021 issue of National Geographic magazine.
A version of this story was originally published on July 7, 2020. It has been updated.
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