Where Is the World’s Oldest Tree?

The world’s oldest confirmed living tree is a gnarled bristlecone pine found in a remote patch of high-altitude forest in the White Mountains of Eastern California. The 4,850-year-old tree, named Methuselah, stands within the Inyo National Forest, but its precise location is kept secret by the U.S. Forest Service to protect the ancient pine from throngs of selfie-seeking tourists.

Methusaleh was discovered in the 1950s by Edmund Schulman, a pioneer in the field of dendrochronology—the science of determining the age of trees. Schulman was the first to identify bristlecone pines as a distinct species of conifer with unrivaled longevity. In a landmark scientific paper, Schulman credited the bristlecone’s extreme living conditions for producing ultra-hardy individuals like Methuselah that have survived nearly 5,000 years.

“Bristlecones grow in a really cold and dry environment up there at the top of the White Mountains,” says Peter Brown, a dendrochronologist who maintains the “OldList,” an online database of the world’s oldest trees. “The oldest tree species and the oldest individual trees tend to grow in these very stressful and marginal environments, which makes them grow very, very slowly.”

Unlike majestic giant sequoias and coastal redwoods—two of the other longest-living tree species—bristlecones appear stunted, twisted and nearly dead. That’s because of a survival technique called “sectored architecture” in which only a thin strip of the bristlecone’s bark is alive at any given time, connecting a small section of living roots to a single sprig of green pine needles.

Methuselah is the oldest living bristlecone in Brown’s database, but that doesn't mean that even older trees aren’t out there. In 1964, a geographer named Donald Currey cut down an ancient bristlecone known as Prometheus in the White Mountains that he determined to be 4,900 years old. Prometheus is the oldest confirmed tree on Brown’s list, but all that remains of that record-breaking pine is a polished slab kept in the Great Basin Visitor Center in Nevada.

Could there be a living bristlecone that's older than 5,000 years? Brown says there is, although the tree’s exact location is shrouded in mystery. Schulman, the bristlecone pioneer, kept meticulous notes from his 1950s expeditions into the White Mountains, and he identified a specimen in the same grove as Methuselah that Schulman determined to be 5,065 years old.

But in 1958, the same year Schulman’s work was featured in National Geographic, he died from a heart attack at just 49 years old. Schulman was the first victim of what Brown calls the “bristlecone curse.”

Three of Schulman’s successors at the University of Arizona’s Laboratory of Tree-Ring Research also died young. Dendrochronologist Tom Harlan claimed to have found Schulman’s 5,065-year-old bristlecone, but he too died before publishing its details. Until its existence is confirmed (and the curse lifted), Brown has decided to keep the unnamed 5,000-plus-year-old tree off his official list.

At its most basic level, dendrochronology is the science of counting tree rings. Tree rings form because most trees outside of the tropics stop growing during the winter. Each ring of the tree’s trunk represents a year’s growth—how much the tree grew from one winter to the next.

Trees don’t need to be chopped down to get a good look at their rings. Dendrochronologists use a special tool called an “increment borer” to extract a core sample of tree rings without damaging the tree. The hollow-tipped borer doesn’t even need to drill to the center of the tree as long as the core sample can be compared with nearby trees.

All trees of the same species in a patch of forest will display growth patterns that reflect the climatic conditions of the time. More rain or warmer temperatures will produce wider growth rings. Less rain or longer winters will produce narrower rings. True drought conditions produce rings that are impossibly small or completely absent.

If a dendrochronologist knows when a nearby tree was chopped down, they can can look at that tree’s ring patterns and try to match them with a section of rings sampled from the living tree.

"It's this idea of cross-matching those climatically driven ring growth patterns,” says Brown, director of Rocky Mountain Tree-Ring Research, a nonprofit research organization in Colorado. “You start with a known date and work backwards, developing a chronological library of ring patterns.”

For slow-growing trees like the bristlecone pine, there may be as many as 100 rings per inch, which requires the careful counting and comparing of ring patterns under a microscope.

Counting tree rings only works in higher latitudes and elevations, where trees stop growing each winter. In the tropics, trees never truly stop growing, so they don’t produce distinct annual rings. In those climates, radiocarbon dating is one of the only ways to determine a tree’s age, although it’s not as precise as dendrochronology.

The oldest radiocarbon-dated tree on Brown’s OldList is a baobab in Northeast Namibia that was determined to be 1,275 years old, plus or minus 50 years.

Sweden also claims to be the home of the world’s oldest tree. A battered Norway spruce known as “Old Tjikko” stands atop a windswept mountain peak in Sweden’s Fulufjallet National Park. The visible part of the tree—its trunk and branches—is only a few hundred years old, but Swedish scientists used radiocarbon dating to determine that portions of Old Tjikko’s underground root system are more than 9,500 years old.

The Norway spruce is known as a “clonal” tree, meaning that it can sprout new growth from the same ancient root system.

“It's a very good evolutionary mechanism to survive disturbances like fire,” says Brown. “The above-ground portion of the tree gets burned off, but the below-ground portion can generate a new tree.”

Brown doesn’t include clonal trees on the OldList, because there isn’t a scientific consensus that trees like Old Tjikko are genetically continuous with their much older root systems. That said, Old Tjikko is definitely the oldest-known Norway spruce.