In the Wasatch Mountains of the western United States, on the slopes above a spring-fed lake, dwells a single giant organism that provides an entire ecosystem upon which plants and animals have depended for thousands of years.
Found in my home state of Utah, “Pando” is a 106-acre stand of aspen clones.
Although it looks like a forest of individual trees with striking white bark and small leaves that flutter in the slightest breeze, Pando (Latin for “I spread”) actually has 47,000 genetically identical stems that flow from an interconnected root network.
This unique genetic individual weighs approximately 6,000 metric tons. By mass, it is the largest single organism on Earth.
aspens tend to form clonal stands elsewhere, but what makes Pando interesting is its enormous size. Most clonal aspen stands in North America are much smallerthose in the western United States averaging only 3 acres.
Pando has been around for thousands of years, potentially up to 14,000 years old, although most stems only live for about 130 years. Its longevity and remoteness mean an entire ecosystem of 68 plant species and many animals have evolved and been sustained under its shadow.
This whole ecosystem relies on the aspen staying healthy and upright. But, although Pando is protected by the United States National Forest Service and is not at risk of being shot down, it is at risk of disappearing due to several other factors.
Deer eat the youngest “trees”
Overgrazing by deer and elk is one of the biggest worries. Wolves and cougars once controlled their numbers, but herds are now much larger due to the loss of these predators.
Deer and elk also tend to congregate in Pando as the protection the forest enjoys means they are not at risk of being hunted there.
As old trees die or fall, the light reaches the wooded ground which stimulates the growth of new clonal stems, but when these animals eat the tops of newly formed stems, they die. This means that in large parts of Pando there is little new growth.
The exception is an area that was fenced off decades ago to remove dying trees. This fenced area excluded elk and deer and saw successful regeneration of new clonal stems, with dense growth referred to as a ‘bamboo garden’.
Diseases and climate change
Older Pando stems are also affected by at least three diseases: sooty bark canker, leaf spot and conch fungus disease.
While plant diseases have developed and thrived in aspen stands for millennia, it is unclear what the long-term effect on the ecosystem may be, given that there is a lack of new growth and an ever-growing list of other pressures on the clonal giant. .
The fastest growing threat is climate change. Pando was born after the end of the last ice age and has since faced a largely stable climate.
Admittedly, he lives in alpine region surrounded by desert, which means it’s no stranger to hot temperatures or drought. But climate change threatens the size and lifespan of the tree, as well as the entire ecosystem it supports.
Although no scientific studies have specifically focused on Pando, aspen stands have struggled 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 leaveswhich led to decline in coverage.
With increased competition for ever-dwindling water resources (nearby Fish Lake is just out of reach of the tree’s root system), temperatures are expected to continue reach record highs in the summer, and the threat of more intense wildfires, Pando will certainly struggle to adapt to these rapidly changing conditions while maintaining its size.
The next 14,000 years
Yet Pando is resilient and has already survived rapid environmental change, particularly when European settlers began inhabiting the area in the 19th century or after the rise of recreational activities in the 20th century. It has already dealt with diseases, forest fires and grazing and remains the largest scientifically documented body in the world.
Despite cause for concern, there is hope as scientists help us unlock the secrets of Pando’s resilience, while conservation groups and the US Forest Service work to protect this tree and its associated ecosystem. And a new band called the Pando Friends aims to make the tree accessible to virtually everyone through 360° video recordings.
One summer, while visiting my family in Utah, I took the opportunity to visit Pando. I spent two amazing days walking under towering mature stems swaying and “soaking” in the gentle breeze, between thick new growth in the “bamboo garden”, and even lovely meadows that puncture parts of the center otherwise closed.
I marveled at the wildflowers and other plants that thrived under the dappled shade canopy, and enjoyed spotting pollinating insects, birds, foxes, beavers and deer, all using part of the ecosystem created by Pando.
These are the moments that remind us that we have plants, animals and ecosystems worth protecting. In Pando, we have the rare chance to protect all three.
Richard Elton WaltonPostdoctoral researcher in biology, Newcastle University.
This article is republished from The conversation under Creative Commons license. Read it original article.
An earlier version of this article was published in November 2021.