The World's Largest Organism Might Be About to Break Up

The largest single organism in the world could soon fracture into smaller pieces.

According to research published in the journal Conservation Science and Practice, this enormous forest organism, known as "Pando," may be about to break up due to "chronic herbivory," or overfeeding by animals.

While it may look like a normal aspen forest in Utah, this 100-acre structure is actually the same organism. Pando is thought to have a dry weight mass of around 13 million pounds and is composed of genetically identical trees sharing one gargantuan root system. It is believed to be up to 14,000 years old.

Plants can create genetically identical clones via off-shooting suckers, or basal shoots. These offshoots allow the plant to establish an identical version of itself in another location, growing into the ground and eventually joining root systems. This "vegetative dispersal" is a form of asexual reproduction, and is seen in a variety of other plants, including Canada thistle, cherry trees, apple trees, hazel trees, tree of heaven, and Asimina triloba.

aspen trees
This stock image shows aspen trees in the Rocky Mountains. Pando, an aspen forest filled with genetically identical trees, is the worlds largest organism due to a huge shared root system. iStock / Getty Images Plus

According to the paper, authored by Paul C. Rogers, an adjunct professor of ecology in the Quinney College of Natural Resources and director of the Western Aspen Alliance, deer and cattle have been threatening Pando by eating new sprouts, limiting the structure's longevity: as older trees die, there are fewer young shrubs to replace them.

"Findings show that the genetically uniform Pando is "breaking up" because of herbivory and fencing," Rodgers wrote in the paper. "This iconic aspen clone has experienced persistent browsing over recent decades by mule deer (Odocoileus hemionus Raf.) and cattle (Bos taurus L.) such that it is slowly dying; a once-dense canopy is thinning out while vegetative offspring (regenerating suckers) fail to reach maturity."

Previous attempts to prevent Pando's decline, such as erecting fences to prevent the herbivores from eating the newer trees, have only exacerbated the problem, possibly segregating the organism into fractured zones.

"Fences have been erected to mitigate herbivory at Pando, but such visual and ecological intrusions potentially bring additional problems, such as creating esthetic impairments and novel floristic pathways at this natural wonder," Rodgers said.

"Fencing to limit herbivory is a logical first-step after decades of failed recruitment, although barriers appear to be having unintended consequences, potentially sectioning Pando into divergent ecological zones rather than encouraging a single resilient forest."

Additionally, only around 16 percent of the organism is adequately fenced to keep out herbivorous animals, with over a third of Pando's fencing having fallen into disrepair, and over half of the structure having no fence at all, according to These differing impacts in various areas also serve to fragment the forest.

Media attention towards Pando and its decline has also further threatened the organism: "Current browsing pressure, alongside increasing human traffic, forecasts a bleak future for Pando," Rodgers wrote in the paper.

Current short-term strategies to restore Pando also include the culling of the herbivores, or reintroducing predators of the deer and cattle to restore a predator-prey balance. However, these are large-scale and expensive approaches.

Pando's decline will also have ripple effects on the local ecology in the area. Aspen forests are often a keystone species in an ecological system. The success of those on either side of the forests on the food chain is heavily impacted by their presence, according to the American Museum of Natural History. Aspen forests like Pando, therefore, support high levels of biodiversity, and Pando's fracturing may have large impacts on various dependent species.

"Aspen forests worldwide support outsized biodiversity, but at Pando overabundant browsers are usurping resilience with anticipated negative outcomes on community diversity," Rodgers wrote.