Pando, also known as the trembling giant, is a clonal colony of an individual male quaking aspen determined to be a single living organism by identical genetic markers and assumed to have one massive underground root system. The plant is located in the Fremont River Ranger District of the Fishlake National Forest at the western edge of the Colorado Plateau in south-central Utah, United States, around southwest of Fish Lake. Pando occupies and is estimated to weigh collectively, making it the heaviest known organism. The root system of Pando, at an estimated 80,000 years old, is among the oldest known living organisms. Pando is currently thought to be dying. Though the exact reasons are not known, it is thought to be a combination of factors including drought, grazing, human development, and fire suppression. The Western Aspen Alliance, a research group at Utah State University’s S.J. & Jessie E. Quinney College of Natural Resources, has been studying the tree in an effort to save it, and the United States Forest Service is currently experimenting with several sections of it in an effort to find a means to save it. Grazing animals have threatened Pando's ability to produce young offsprings to replace trees that are dying. Human development in the area is another threat; these two threats have caused pando trees to shrink in size and decrease over the past 50 years. A study published in October 2018 concludes that Pando has not been growing for the past 30–40 years. Human interference was named as the primary cause, with the study specifically citing people allowing cattle and deer populations to thrive, their grazing resulting in fewer saplings and dying individual trees.
History
During intense fires, the organism survived underground, with its root system sending up new stems in the aftermath of each wildfire. If its postulated age is correct, the climate into which Pando was born was markedly different from that of today, and it may have been as many as 10,000 years since Pando's last successful flowering. Additionally, the post glacial climatic conditions have made it very problematic for new seeds to sprout. According to an Organisation for Economic Co-operation and Development report in 2000: The clone now known as Pando was discovered in 1968 by researcher Burton V. Barnes, who continued to study it through the 1970s. Barnes had described Pando as a single organism based on its morphological characteristics alone; molecular techniques and methods developed since that time have largely substantiated those conclusions. Building on Barnes's earlier work, Michael Grant of the University of Colorado at Boulder re-examined the clone, named it "Pando", and claimed it to be the world's most massive organism in 1992. In 2006 the United States Postal Service published a stamp in commemoration of the aspen, calling it one of the forty "Wonders of America."
Size and age
The clonal colony encompasses, weighs nearly, and has over 40,000 stems, which die individually and are replaced by new stems growing from its roots. The average age of Pando's stems is 130 years, as indicated by tree rings. The roots are 80,000 years old. Jeffry Mitton and Michael Grant in BioScience said:
Debate
Tree experts also note that the organism's age cannot be determined with the level of precision found in tree rings; some claim Pando's age is closer to 1 million years. Its current 80,000-year designation is based on a complex set of factors, including the history of its local environment, the evidence indicating that there are few if any naturally occurring new aspens in most of the western United States since a climate shift took place 10,000 years ago which eliminated favorable soil conditions for seedlings, the rate of growth, its size, and its genome in comparison to the mutations found among aspens born in the modern era. Michael Grant and Jeffry Mitton summed it thus: Conversely, other observations in the region show that seedling establishment of new clones is regular, and often abundant on sites exposed by wildfire. J. L. Howard states: Other candidates for oldest or heaviest living organisms include the possibly larger fungal mats in Oregon, the ancient clonal creosote bushes, and strands of the clonal marine plantPosidonia oceanica in the Mediterranean Sea.
