Kamal Ghorui
In the temperate rainforests of Chile’s Alerce Costero National Park, deep in the ground, is an ancient conifer called ‘Gran Abuelo’ that has been protecting a hidden secret for thousands of years. A recent study published in the journal Biodiversity and Conservation has revealed the tree’s greatest value lies in what is hidden beneath the surface. Researchers investigated soil samples taken from Gran Abuelo and found an undiscovered world of life within. By examining soil samples, they identified a community of over 300 fungal species, many of which are unique to this ancient soil and found nowhere else on Earth, which form a mycorrhizal network with Gran Abuelo. This mycorrhizal network not only provides essential nutrients and water to Gran Abuelo; it also serves as the foundation of the entire forest’s microbial ecosystem. All experts stress that if we lose one of these ancient trees, it could create a domino effect throughout the forest’s entire carbon cycle.
What exactly is the ‘Gran Abuelo’
The Gran Abuelo – or ‘Great-Grandfather’ – is an enormous Alerce (Fitzroya cupressoides) tree located in Chile’s Alerce Costero National Park. It has a height of over 60 feet and a trunk diameter that exceeds 13 feet. Alerces are native to the temperate rainforests of Patagonia and have existed for thousands of years. While some researchers still debate its age, environmental scientist Jonathan Barichivich recently estimated through computer modelling and partial core sampling that the Gran Abuelo is nearly 5500 years old. That would make it older than ‘Methuselah,’ the Bristlecone pine located in California, and perhaps the oldest living individual tree on Earth.
The unbelievable discovery under Earth’s oldest tree
The unbelievable finding was not how old this tree is; however, it was how much life it supports underground! As written in PhysOrg, researchers used a genetic technique, called DNA sequencing, to map the ‘mycorrhizal’ (fungal) networks around the Gran Abuelo tree. They found out that the soil below this ancient giant is 2.25 times more biodiverse than the soil below other more recently grown trees in the same forest; in fact, they discovered over 300 species of fungi in this ‘microbial metropolis,’ many of which you cannot find anywhere else in the world.
How fungi kept the world’s oldest tree alive
This discovery shows that the Gran Abuelo tree is not just a plant but instead serves as a hub for a biological support system. Experts from the Royal Botanic Gardens in Kew say that these fungi create a mutualistic relationship with the tree – the tree provides the fungus with sugar (carbon) through photosynthesis, while the fungus acts as an extension of the tree’s root system by reaching into the ground deep enough to provide phosphorus, nitrogen, and water back to the tree during periods of severe drought. Therefore, it is likely that this ancient network is what has kept this tree alive against fires, climate change, and centuries of environmental stress.
A 30,000-year timeline
Though the tree is thought to have been around for about 5,000 years, the WWF also states that the region acted as an ‘ice age refuge,’ allowing the soil biomes to evolve undisturbed for over 30,000 years- long before the Gran Abuelo itself took root; thus, creating large underground networks that store carbon dioxide deep within the earth. If the ancient trees fall victim to climate change or human interference, scientists warn that the resulting loss of this 30,000-year-old carbon storage system will cause a release of enormous quantities of greenhouse gases back into our atmosphere.
