16 June 2018

The Bristlecone Pine: Twisted Contortions of the Ancients

They have lived through millennia. Dispersed in sub-alpine groves in the Western United States some of these ancient trees are over 5,000 years old.  They contain in their ranks the oldest known individuals of any species on Earth. Their twisted branches, formed over innumerable years stretch towards the sky, sublimely if anthropomorphically expressive. What might these immovable ancients have pondered as epochs passed?

Image Credit David Wood
Yet why are these pine trees so contorted?  The answer is in the wood of the bristlecone.  It is so dense and resinous that it is particularly resistant to attack by insects.  For the same reason it is almost impervious to fungal assault or any other potential vexations which their surroundings can inflict.  Their neighbors, less resilient and tenacious species, wither and die, wither and die: yet the bristlecone endures – often even after death.

Image Credit Jesse Varner
Image Credit Tony Frates
These incredible trees did not always look this way.  When young their branches are smooth and straight. They have enemies, those forces which can erode even stone: the elements.   Wind, rain, sun, cold – these foes have all conspired to destroy these primeval pines over the year, but although they have left their mark all have failed. The bristlecone pine becomes with age, twisted, contorted, warped.  These bizarre forms, embodying so many of our earthly agonies and ecstasies, add to our wonder when we encounter these incredible trees.

Image Credit David Fulmer
Image Credit David Wood
Image Credit Mike Cross
Even when death claims them the shape of the tree persists. The roots, so strong and dense, may support a tree’s cadaver for centuries. For many, death is a prolonged process.  Much of the vascular tissue of the trees eventually dies, leaving behind an incredibly thin strip of living material but still enough for a few live branches to linger  The needles, like the tree, can age: yet while they photosynthesize and regulate water there is life.

Image Credit J Brew
Image Credit Eric Carlson
Image Credit Richard Clarke
Ironically the dead wood may well be that which allows life to continue, that the incredible longevity of the bristlecone is directly in relation to the high ratio between dead and living wood.  It is thought that as this ratio increases then it inevitably diminishes water loss as well as respiration. The life of the tree is extended. Perhaps the life of the bristlecone is, in fact, an act of suicide which last for centuries.

Image Credit John Bushinsky
Image Credit John Bushinsky
Image Credit Kittell
However, there may be trouble ahead for the three species of bristlecone pine.  As it has such a low rate of both reproduction and regeneration it is feared that our changing climate might make it impossible for the pine to sustain its numbers.  Not only that, but a species of rust fungus has made its way to the trees’ habitat from far-flung Asia, arriving on the continent a century ago but finally reaching the high altitudes of the American West just a few years ago.

Image Credit Fred Moore
Image Credit Richard Droker
Image Credit im me
Not only that.  The rising temperatures have meant that the native pine beetle has also been able to make inroads in to the bristlecone’s ancient territory.  The tree does not have any natural immunity to either the rust or the beetle. The future may not be secure for the bristlecone pine but, having already endured epochs, one can only hope they can persevere for another age.

Image Credit Nick Turland
While saplings continue to sprout there is, after all, hope.  Who knows? In a few thousand years the young tree above may look like this...

Image Credit Jim Morefield

Fist Image Credit David Wood