Rainforests cover only 6‑7% of Earth’s land but host 70% of the planet’s plant and animal species, according to the World Rainforest Fund. Yet scientists have catalogued fewer than 10% of those species. In Chile’s Alerce Costero National Park, researchers recently discovered a hidden world of fungi beneath the park’s ancient conifers.
The study, published in Biodiversity and Conservation in 2022, set out to map the mycorrhizal networks and soil samples around the park’s alerce trees—Chile’s second‑oldest tree species. Alerce trees grow slowly, can reach 15.5 ft in diameter and 164 ft in height, and have a remarkably low mortality rate. Field teams sampled soil from individual trees ranging from saplings to more than 2,400 years old.
Remarkably, the largest, oldest tree yielded 2.25 times the fungal diversity of younger trees and contained over 300 unique fungal species. The data confirm that these giants provide a specialized micro‑environment that nurtures a vast fungal community.
The relationship between alerce trees and their fungal partners is mutually beneficial. Mycorrhizal fungi help channel nutrients and water into the trees’ root systems, bolstering resilience against drought and disease. In turn, the trees offer a protected habitat for fungi.
Beyond supporting tree health, these fungi play a critical role in carbon sequestration. By storing carbon in the soil, they contribute to the park’s status as a major carbon sink—an essential component of the global climate system.
These findings underscore the importance of conserving alerce forests. The park’s original range has already been halved by centuries of deforestation, and the oldest tree was felled in 1976 at 3,622 years old. Loss of these millennial trees would mean a dramatic decline in soil fungal diversity, threatening the integrity of an ecosystem that has taken millennia to build.
Protecting the alerce trees is therefore not only about preserving iconic ancient trees; it is also about safeguarding a vast, largely unknown fungal biome that sustains the forest’s ecological and climate functions.
