Although it looks like a woodland of individual trees with striking white bark and small leaves that flutter in the slightest breeze, Pando (Latin for “I spread”) is actually 47,000 genetically identical stems that arise from an interconnected root network. This single genetic individual weighs around 6,000 tonnes. By mass, it is the largest single organism on Earth.

Pando has been around for thousands of years, potentially up to 14,000 years, despite most stems only living for about 130 years. Its longevity and remoteness mean a whole ecosystem of 68 plant species and many animals have evolved and been supported under its shade. This entire ecosystem relies on the aspen remaining healthy and upright. But, although Pando is protected by the US National Forest Service and is not in danger of being cut down, it is in danger of disappearing due to several other factors.

Deer are eating the youngest ‘trees’

Overgrazing by deer and elk is one of the biggest worries. Wolves and cougars once kept their numbers in check, but herds are now much larger because of the loss of these predators. Deer and elk also tend to congregate in Pando as the protection the woodland receives means they are not in danger of being hunted there.

Diseases and climate change

Older stems in Pando are also being affected by at least three diseases: sooty bark canker, leaf spot and conk fungal disease. While plant diseases have developed and thrived in aspen stands for millennia, it is unknown 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 that of climate change. Pando arose after the last ice age had passed and has dealt with a largely stable climate ever since. To be sure, it inhabits an alpine region surrounded by desert, meaning it is no stranger to warm temperatures or drought. But climate change threatens the size and lifespan of the tree, as well as the whole ecosystem it hosts.