NOVA Online | Methuselah Tree
 Like tree, like needle: Bristlecone needles may survive for as long as three or four decades. |
Part 2 | Back to Part 1 A tree's tricks Well, for starters, because bristlecones live where practically nothing else can, little competition exists for water and nutrients. Bristlecone pines can liberally spread their roots and expand their crowns, maximizing intake of these scant resources. Sparse ground cover means the threat of fire is greatly reduced, a danger further lessened by the relative paucity of dead bristlecone needles in a landscape where trees are few and far between. Like the trees that produce them, bristlecone needles are long-lived; they last up to 30 or 40 years. While living bristlecone limbs thus carry a heavy load of needles, such a stable needle mass may prove an advantage in the severe environment of the White Mountains.
Bristlecone rings, which vary in width year to year, reveal that the trees have an innate ability to endure times of stress, such as a string of drought years. In such periods, the species can go almost dormant. "There is something a little fantastic," wrote Edmund Schulman in the March 1958 National Geographic, "in the persistent ability of a 4,000-year-old tree to shut up shop almost everywhere throughout its stem in a very dry year, and faithfully to reawaken to add many new cells in a favorable year."
Another type of stress, one that torments most other plants, is virtually absent among bristlecone pines: disease. The tree has a dense, highly resinous wood that is a formidable barrier to invasion by insects and bacteria. The resinous wood and the White Mountains' cool, dry climate also appear to keep rot-causing fungi at bay, so that dead bristlecones sometimes stand for several hundred years before toppling. In fact, the oldest bristlecone pines live on the most exposed sites.
 Squat but steadfast, bristlecones put more stock in surviving than in soaring. |
Indeed, the bristlecone pine goes in for reduced size in a singular way. It is an ability that, perhaps more than any other, allows the species, in standout cases, to last longer than most civilizations. When a major root dies, through decay by root-rot fungi or by exposure to desiccating winds, the sector of the trunk above that root also succumbs, along with any branches served by that sector. In time, the affected sector's bark falls off, leaving bare trunkwood. Some gnarled old bristlecones have only a thin strip of living bark, which sustains a single living branch and its needles. In a sense, these ancients have gone back to being seedlings.
 Bristlecones that look almost dead may have been "almost dead" for millennia. |
Now, if only King Tut and the rest of us brief-lived humans could have figured out a way to hang on so long.
Peter Tyson is editor in chief of NOVA Online.
Further reading
Lanner, Ronald M. 1999. Conifers of California. Los Olivos, Calif.: Cachuma Press, pp. 47-51.Mohlenbrock, R.H. 1985. "Ancient Bristlecone Pine Forest, California." Natural History 94(5): 38-41.
Schmid, R. and M.J. "Living Links With the Past." Natural History 84(3): 38-45.
Schulman, E. 1958. "Bristlecone Pine: Oldest Known Living Thing." National Geographic Magazine 113(3): 354-372.
Explore the Methuselah Grove | A Tree's Secret to Living Long
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