New research from Chile shows that the country's giant Alerce trees are doing more than storing centuries of growth above ground. Beneath their roots, they support exceptionally rich fungal communities that make them true biodiversity hubs.
The study focused on Fitzroya cupressoides, one of the world's longest-lived tree species. Some individuals have survived for more than 3,600 years, while the famous Gran Abuelo has been estimated at roughly 5,484 years old, although that figure still awaits independent verification.
Scientists sampled soil around 31 trees of different sizes in Chile's Coastal Range and used DNA metabarcoding to map the underground fungal life. The results were clear: larger, older trees hosted far more fungal diversity than younger ones. Around Alerce Abuelo, fungal richness was 2.25 times higher than the sample average, with 361 unique fungal OTUs identified.
The study also highlighted the role of arbuscular mycorrhizal fungi, which live in close partnership with plant roots. These fungi help plants absorb nutrients and cope with environmental stress, while receiving carbon in return. In this way, ancient trees help sustain a complex underground network that supports forest health.
Researchers noted that soil phosphorus levels also shaped fungal diversity, with richer fungal communities appearing where phosphorus was less available. That pattern suggests that tree age, size, and soil conditions together influence the underground ecosystem.
The findings add a new reason to protect Chile's slow-growing Alerce forests, which face pressure from habitat loss, climate change, and wildfires. Preserving the largest remaining trees may also safeguard the hidden fungal systems they have nurtured for millennia. In the future, this insight could reshape how forests are protected and restored.
