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The Heaviest Organism on the Planet

November 30th, 2016|Tags: |


By Doyle Irvin, American Forests

Believe it or not, the aspens on both sides of this road are all one tree. Credit: Robert Shea via Flickr.

Believe it or not, the aspens on both sides of this road are all one tree. Credit: Robert Shea via Flickr.

In the high-altitude reaches of Utah’s Fishlake National Forest lives a forest that has captured the world’s attention. Pando, Latin for “I Spread,” is not your normal collection of trees. There may be 47,000 individual trunks sprouting from the ground, but the grove itself is actually one large interconnected clonal colony, with a massive underground root system connecting its entirety. Long story short, the forest is actually all one living being, originating from the same single seed.

An aspen seed is a tiny, flighty affair, minuscule enough to float on the wind. Now, Pando is easily the world’s heaviest living thing, weighing an estimated 6,600 tons. The trees are genetically identical, one single male quaking aspen (Populus tremuloides) that has spread to cover 106 acres of hillside.

Pando, and clonal colonies like it, reproduce through what is called “suckering,” which is when one stem (or “trunk”) sends out lateral roots that then become new stems (or “trunks”). While the stems themselves rarely live past 100 to 150 years, the organism itself sustains its life for thousands upon thousands of years. The most accepted estimate currently for Pando’s age is approximately 80,000 years, but because that estimate is based on aspen rates of expansion and projections back in time of what the climates are guessed to have been, the 80,000 mark is understood as rough. Some researchers claim that it could be closer to a million years old!

How did it become the king? Researchers assert that Pando has grown under ideal circumstances for the majority of its lifetime. Frequent low intensity burns keep competition from invading its territory, and the climate shift in Utah in the last 80,000 years has created circumstances where rival aspens are unlikely to flower. It is currently thought that Pando itself has not reproduced through seeds in the last 10,000 years. It is potentially possible for Pando to reproduce once again through seeds, as is usual for aspens to do on the east coast and elsewhere, but it is not easy for these colonies out west — they have three sets of chromosomes instead of two, and the landscape is too dry.

Pando is now dying. The change in predator-prey ecosystems out west is a large contributor to this. Tree colonies, like Pando, require a constant influx of new sprouts to survive, and an overpopulation of deer, elk, sheep and cattle has been eating juvenile sprouts before they can mature into full trunks. The existing population of trunks is now passing middle age, and there isn’t a new generation to follow them. To complicate matters, the mature trunks themselves are dying at an abnormally high rate, which researchers are attributing to a climate-change related influx of disease and insects.

There’s a chance that a larger clonal colony exists somewhere on the planet, as Pando is thought to have been discovered primarily because a road runs right through it. However, as clonal colonies are fairly easy to spot — the leaves all change at the same time — this may not be the case. Whether or not it is indeed the largest, one thing is undeniable: it is spectacular. Efforts are being made to protect our planet’s reigning largest organism. The U.S. Forest Service is fencing off 67 acres of it for protection and experimentation, hoping to get a good response to various sprout-stimulants they have in mind.

November 30th, 2016|Tags: |0 Comments

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