It’s made of 47 thousand genetically identical stems, but now this unique forest is at risk of extinction: the world’s largest organism risks death because of deer
If we think of the world’s largest living organism, whales come to mind, or a large oak tree. If, however, we think of the world’s largest single-celled organism, the first assumptions are about the cells: certainly small and invisible, but larger than their counterparts.
They would be wrong: the world’s largest single-celled organism is a forest of quaking aspens in Utah, USA. And deer are devouring it.
The aspen forest
In the Wasatch Mountain Range in the western United States, there’s a grove that overlooks a lake. It looks like a normal mountain picture, but it’s not: the forest is a single, gigantic organism, which has created an entire ecosystem thanks to which plants and animals have survived for hundreds of years.
It’s called “Pando”, and it’s a set of 106 trees, one particular quaking aspen, which are clones of each other. The term pando comes from Latin, and means “to expand.” At first glance it looks like a forest of saplings with a white trunk, bare in this season and covered with small leaves in summer. In reality, it is 47 thousand genetically identical stems that grow from a network of interconnected roots. It’s a single genetic individual that weighs 6 tons, the largest in the world.
Tremulus poplar has this characteristic, of forming “clone stems,” and it does this in other parts of the world. But nowhere so much. Pando, the giant forest, has been around for at least 14,000 years, although individual trees live up to 130 years. In that long time, it has created an ecosystem with 68 plants and dozens of animals that have been born and survived thanks to Pando.
Thanks to American laws, Pando is protected: there’s no risk of it being cut down to make a road or a parking lot. But there are other risks.
Deer and climate change
One of the biggest risks to Pando comes from the animal world: one of the biggest concerns comes from deer and elk, which are eating too many leaves and stems. It used to be that wolves and cougars reduced the number of elk and deer by hunting them, but the number of predators is dwindling and the number of herbivores is increasing as a result – which, by the way, have found Pando to be a great hiding place to escape hunters.
When a Pando tree falls, more sunlight reaches the stems that have just come out of the ground, which grow faster. But that also becomes faster food for deer. In fact, in some areas of Pando there is very little new stem growth. But there’s one area that was fenced off, where elk and deer can’t enter, and new stems are blooming there.
There are also diseases that affect Pando’s trees: those carried by an insect, the bark beetle, leaf spots and fungal diseases. And finally, climate change: the drought that affects the area and the higher temperatures the first few months of the year make it more difficult to produce new leaves. Not to mention the increasingly frequent forest fires. And it’s not the only plant species at risk of disappearing because of climate change.
But Pando has proven to be very resilient: it has survived fires, disease, deforestation and invasion by European settlers in the 19th century. Scientists are trying to understand the secrets of this resilience to better protect Pando.