Bristlecone Pines

Bristlecones survive so long for several reasons. One is that they live in areas so extreme they don't compete with other plants. Another is that their cells don't show signs of 'senescence' -- an ancient cell from a bristlecone looks and functions a lot like a young one, unlike human cells which age. A third reason, I believe, is that they have survived because their habitat isn't useful to us. Once we find some use for windswept 10,000 ft rideglines (besides a context for personal enlightenment and metaphorical soul-searching), watch out.

Bristlecone pines have what's called sectored architecture. That means a particular clump of roots at the bottom provides a particular clump of branches at the top (or side) water, through a stem channel specific to those parts of the tree. So, when a root section is damaged the part of the tree associated with that section dies.  Often old Bristlecones, and especially ancient ones (a term which generally applies to trees past the 4,000 yr old mark -- the rest are merely 'old') display a section of living tree wrapping and winding its way around a mass of dead wood.

One thing that keeps the dead wood from disintegrating over the millennia is the trees' resin, which effectively seals the wood like a sock dipped in candle wax. The resin also helps the tree seal up wounds. It is for this reason that scientists can take core samples from the tree with an increment borer to analyze its rings and make an estimation about its age and the climatic conditions it has experienced.
The increment borer is like a hollow drill bit, so it can remove rods of wood the diameter of a pencil and several feet long. Because the hole is so small, it seals up with resin quickly. These rods of wood, often indicating thousands of rings, are then compared to other hollow rods of wood from other interesting trees. By combining overlapping patterns in core samples from different trees, scientists can assemble a climate history tens of thousands of years old. These folks are known as 'dendrochronologists' and 'extremely patient'. Interestingly, these patterns can also be used to date core samples taken from roof timbers in ancient dwellings.

Given that these techniques have been around since the 60's, it is fascinating that a guy named Donald Currey decided to cut down what seemed to him an especially interesting tree in 1964 just near Wheeler Peak in what is now Great Basin National Park. To make a long story short, the tree he cut down was the oldest one we've ever found. It was 4,862 years old.

It's a fascinating story involving different measures of science, ignorance, and politics depending on who you ask. Take a look at Michael Cohen's "A Garden of Bristlecones: Tales of Change in the Great Basin" for a good overview.

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