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A Memory Bank for the Planet

Rings of bristlecone pines, Earth's oldest trees, hold clues to global warming and human history. A scientist seeks missing link in a record of nearly 12,000 years.


ANCIENT BRISTLECONE PINE FOREST, Calif. -- The twisted sentinels of this desolate forest are a study in perseverance. Contorted by wind, deprived of rain, starved by the nutrient-poor dolomite slopes to which they cling, they have been known to live nearly 5,000 years. Snags--majestic trees that have died but remain standing--and the limbs they've dropped, have rested more than twice that long, their resinous wood resistant to rot.

Beautiful and grotesque, the bristlecone pines in the White Mountains of eastern California--the world's oldest trees--are a vast memory bank for the planet that can be used to date archeological remains half a world away. Their growth rings--each one representing a calendar year--log the passing seasons. Their tiny variations record climatic changes, volcanic eruptions, years of drought.

Thomas Harlan, 67, is a human soul mate to these resolute plants. Tenacious, persistent, the retired University of Arizona tree-ring scientist has spent years scouring these arid mountains for one singular piece of wood.

Since the ancient trees were discovered nearly half a century ago east of Mammoth Lakes in the mountains along the Nevada line, the scientists who study tree rings --dendrochronologists--have used samples from both living and dead bristlecones to construct a chronology that could cover more than nearly 12,000 years.

For The Record
Los Angeles Times Tuesday September 17, 2002 Home Edition Main News Part A Page 2 National Desk 6 inches; 220 words Type of Material: Correction
Tree rings--A story on bristlecone pines that ran in Friday's Section A misspelled the name of A.E. Douglass, a pioneering researcher in the field of dendrochronology, the study of tree rings. Also misspelled was the name of the Arizona town Show Low.

It lacks only one key piece to make it complete.

The missing link would form a bridge--probably about 150 years long--from one continuous 8,702-year set that stretches back from the present to another, older sequence that covers nearly 3,000 years--with one small gap--but whose exact start is unknown.

It is that sample for which Harlan searches.

For scientists, such a chronology would be a tremendous tool. The bristlecone pines "are like a person living in a single spot who has been watching things happen for a real long time," said David C. LeBlanc, a dendrochronologist at Ball State University in Indiana.

A nearly 12,000-year timeline would offer the first year-by-year account of North America's climate as it emerged from the last Ice Age. It would shed light on the era when the continent was first settled by humans. By helping explain how the last Ice Age ended, it would aid scientists in understanding the current global warming.

Scientists worldwide revere Harlan for his ability to assign precise dates to tree rings. But like the misshapen trees, he thrives in obscurity. A poor ranch kid from the Texas town of Harper, Harlan had planned to be "the world's greatest archeologist." But there was little funding for his research, and he was toting cafeteria leftovers around to make them stretch when the University of Arizona offered a job dating tree rings. He soon became the lab's most accomplished technician.

"I discovered what I really liked was developing long chronologies in areas where nobody else had worked. You know," Harlan said, "the frontier's edges."

He began work at the university's Laboratory of Tree-Ring Research just as bristlecone research was starting. Over the years, four scientists at Arizona have led the field. Harlan has worked closely with all but the first. And he watched each die young, their work unfinished, in a set of unrelated circumstances referred to--only half in jest--as the Curse of the Bristlecone.

Edmund Schulman was the pioneer. He discovered the bristlecones in 1953. Four years later, he encountered his prize--a tree dubbed Methuselah, at 4,768 years widely believed to be the oldest still alive on Earth. (Harlan says he knows of a slightly older tree nearby but refuses to disclose its location, for fear of vandalism). Schulman's find was published in National Geographic in 1958, the year Harlan arrived at the lab, but by then Schulman was dead, felled by a heart attack at 49.

His successor, Wes Ferguson, died at 64, his research incomplete. Val LaMarche, the next big name in bristlecones, died young too, ruined by substance abuse. Don Graybill, who succeeded him, died of stomach cancer in 1993. Each man's work was boxed up and stored in the Tucson laboratory.

Harlan's work, meanwhile, took him to South America, Sweden--and to Morocco, where, under orders of the king, he established a 1,000-year precipitation record using Atlas cedars. But since Harlan first came to this California forest, in 1970, it has been the bristlecones that moved him most.

Whenever he could, he hauled the bristlecone samples of his predecessors out of storage to fine-tune the timeline. When he retired 11 years ago, he continued to search on his own, driving west with his wife, Anita, to trek the peaks and basins on his own dime.

Then last year, an anonymous donor granted the lab $60,000 for a project. Harlan got the money. Now, armed with the small grant and accompanied by dozens of volunteers, he has stepped up the search.

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