You are about to take a hike up in the White Mountains east of Sierra Nevada to a very interesting and unusual place where ancient trees were growing for thousands of years in tranquility, away from the rush of human civilization. The trees are called bristlecone pines. The name refers to spiky cones. The immature cones have dark color, which supposedly helps to absorb heat. We will start our trip with the visitor center of the Ancient Bristlecone Pine Forest. The rangers demonstrated how the age of the trees was identified using a special tool was called an increment borer to take samples of the wood. These growth rings are analyzed and the patterns are matched to create a continuous record for a particular geographic area which provide dating going back thousands years. Obviously, this procedure should be done with care and only on selected trees. The bristlecone pines grow extremely slow and their rings are so short that you would need a microscope to really see them well.
Using this technique, it was established that the age of the trees here could be around 4 thousand years, and some pines may be over 5 thousand years old. The trail starts a few yards from the parking lot and leads the visitors up on the hill slope. Almost immediately, you will see a tree that had fallen several hundred years ago but has not rotted yet. This is because the wood is highly resinous and very resistant to rotting. In fact, it is believed that the dead wood erodes similar way as stone does rather than becoming food for microorganisms.
The ground is rocky, almost lacking any real soil, but these are the best condition for the pines. They like to grow on dolomite, the sedimentary rock of a light, grayish-white color. The color of the rocks is the reason why the whole mountain range is called White Mountains. Dolomite is a sedimentary rock, a kind of limestone, and because of that the condition of the soil is distinctly alkaline, far from optimal for many plants (but not for bristlecone pines).
The views of Sierra Nevada are spectacular. It would be smart take umbrellas to hide from the sun, as there is not much shade on the trail. The trees do not have many needles. The branches look dead, with few green patches on them. Tough conditions require very careful use of the water resources. It’s all about survival rather than flourishing.
The most interesting trees are at the highest points of the trail along the western slope of the hill. Here you can come very close to the trees. Walk under the branches and almost step over the ancient roots. This feels like you are on a quest in a fantasy land. Studies of the tree rings, by the way, helped to calibrate another dating technique called radiocarbon dating, which uses the amount of radioactive carbon isotope, C14, as an indicator of the age of biological materials. I heard that after calibration was done using wood from bristlecone pines, certain dates in the human civilization timeline had to be corrected. Now, bristlecone pines are known as “the trees that rewrote the history”.
Since we talk about radioactivity, I have to mention that the area with brown, iron-rich deposits on the way down the hill, where the trail turns back to the visitor center, seems to have a slightly elevated level of radioactivity. It’s within a safe range, but still several times higher than dolomite, for example. It’s probably best not to hang around the areas with dark rocks, which are red quartzite formed through metamorphic transformation of the sandstone. The old trees here are really spectacular, though… and they look very, very old.
Regardless the nature of the rocks, the high altitude places tend to have higher levels of radiation. This is due to the thinner protective layer of atmosphere above. Let’s remember that we are between 10 and 11 thousand feet above the sea level!
I hope you were able to feel the sense of endurance looking at the trees that proved that they can withstand the harsh conditions for millennia. No complaints, just steady patience. What an inspiration for all of us!
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