The Biggest Living Thing
What is the Earth’s largest living organism by mass, currently? If you didn’t know, you might picture a mammal such as a blue whale or an elephant. Or you may imagine a large single tree such as a giant sequoia. The truth is it’s a clonal colony of quaking aspen (Populus tremuloides) composed of thousands of tree stems covering hundreds of acres in the Fishlake National Forest in Utah. This genetic individual has been named Pando.
Because quaking aspen can reproduce clonally via lateral roots that emerge to form additional stems (also known as “sucker” roots), the aspen tree trunks that make up Pando are genetically identical. And these tree trunks are connected by a single massive root network underground. This is why Pando is considered as one living thing rather than thousands.
The estimates vary, but most scientists figure Pando’s age to be around 14,000 years old, being born about the same time the last Ice Age ended and the glaciers retreated from the area. Aspen tree trunks only live to be about 130 years old, but quaking aspens can replace old trunks over time with new stems via suckering, and thus live a very long time.
Unfortunately, Pando has not been forming new stems at a sufficient rate to keep from declining as its tree trunks age and die. This is figured to be caused by factors correlating to Euro-American settlement of the area, namely fire suppression, cattle grazing, and browsing by mule deer. Hopefully this trend can be reversed before Pando is gone forever.
Now you can tell your friends you know what the biggest living thing on Earth is. It’s Pando, who is basically a forest. Here endeth the lesson.
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