A single enormous creature lives on the slopes above a spring-fed lake in the Wasatch Mountains of western Utah, providing a whole ecosystem on which plants and animals have relied for thousands of years. “Pando” is a 106-acre stand of quaking aspen clones in my home state of Utah. Pando (Latin for “I spread”) is actually 47,000 genetically identical stems that originate from an interconnected root network, despite its appearance of a woodland of individual trees with dazzling white bark and little leaves that flutter in the slightest breeze.
The weight of this one genetic human is estimated to be over 6,000 tonnes. It is the world’s largest single organism in terms of mass. While aspen trees do develop clonal stands in other places, Pando is notable for its vast size. Most clonal aspen stands in North America are substantially smaller, averaging about 3 acres in the western United States.
Despite the fact that most stems only live for about 130 years, Pando has been around for thousands of years, possibly up to 14,000 years. Because of its length and isolation, it has sustained a diverse ecology of 68 plant species and several animals. The aspen’s health and uprightness are critical to the ecosystem’s survival. Despite the fact that Pando is protected by the US National Forest Service and is not in danger of being cut down, it is endangered owing to a number of other issues.
THE YOUNGEST ‘TREES’ ARE BEING EATEN BY DEER. One of the most serious concerns is deer and elk overgrazing. Wolves and cougars used to keep herds in control, but the disappearance of these predators has resulted in much larger herds. Deer and elk also concentrate in Pando because the woodland is protected from hunting, thus they are not in risk of being hunted there. Light enters the woodland floor as older trees die or fall down, stimulating the growth of new clonal stems, but these critters bite the crowns off freshly formed stems, killing them.
This means that there is minimal new growth in huge areas of Pando. The only exception is a section of land that was fenced off to remove dying trees a few decades ago. Elk and deer have been kept out of this fenced-in area, which has seen successful regeneration of new clonal stems and dense growth dubbed the “bamboo garden.”
CLIMATE CHANGE AND DISEASES, In Pando, at least three diseases damage older stems: sooty bark canker, leaf spot, and conk fungal disease. Plant diseases have evolved and thrived in aspen stands for millennia, but given the lack of new growth and an ever-growing list of additional stressors on the clonal giant, it’s unclear what the long-term effect on the ecosystem will be. Climate change is the most rapidly expanding threat. Pando arose when the previous ice age ended, and has enjoyed a very stable climate since then. It does, after all, live in an alpine region surrounded by desert, so it is no stranger to hot weather or drought.
However, climate change poses a threat to the tree’s growth and lifetime, as well as the ecosystem it supports. Despite the fact that no scientific studies have specifically focused on Pando, aspen stands have been struggling with climate change-related pressures such as reduced water supply and warmer weather earlier in the year, making it more difficult for trees to form new leaves, resulting in coverage declines.
Pando will undoubtedly struggle to adjust to these fast-changing conditions while maintaining its size, with more competition for ever-dwindling water resources (the nearby Fish Lake is just out of reach of the tree’s root system), temperatures expected to continue soaring to record highs in summer, and the threat of more intense wildfires.
