90% of mycorrhizal fungal biodiversity hotspots lie outside protected areas

Scientists have released the world's first high-resolution, predictive biodiversity map of Earth's underground mycorrhizal fungal communities, revealing that over 90% of Earth’s most diverse underground mycorrhizal fungal ecosystems remain unprotected, threatening carbon drawdown, crop productivity, and ecosystem resilience to climate extremes.

Mycorrhizal fungi help regulate Earth’s climate and ecosystems by forming underground networks that provide plants with essential nutrients, while drawing ~13 billions tons of CO₂ per year into soils – equivalent to roughly one-third of global annual fossil fuel emissions. Despite their key role as planetary circulatory systems for carbon and nutrients, mycorrhizal fungi have been overlooked in climate change strategies, conservation agendas, and restoration efforts – only 9.5% of these fungal biodiversity hotspots fall within existing protected areas, underscoring a major gap in current conservation frameworks.

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Using more than 2.8 billion fungal DNA sequences from 25,000 soil samples collected in 130 countries, the study uses machine learning to model global patterns of mycorrhizal fungal diversity at an unprecedented 1 km² resolution. The researchers use the maps to identify underground “hotspots” — areas of exceptional mycorrhizal diversity and rarity — that are vital to soil health, carbon sequestration, and plant productivity.

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“For centuries, we've mapped mountains, forests, and oceans. But these fungi have remained in the dark, despite the extraordinary ways they sustain life on land”, says Toby Kiers, Executive Director of the The Society for the Protection of Underground Networks (SPUN). “They cycle nutrients, store carbon, support plant health, and make soil. When we disrupt these critical ecosystem engineers, forest regeneration slows, crops fail, and biodiversity aboveground begins to unravel. This is the first time we're able to visualize these biodiversity patterns — and it's clear we are failing to protect underground ecosystems.”

The co-authors of the study, Leho Tedersoo, Professor of Mycorrhizal Studies at the University of Tartu's Centre for Mycology and Microbiology, and Vladimir Mikryukov, Research Fellow in Soil Microbiome, supported the completion of the study by providing a large amount of data, identifying fungi and constructing maps. The research is the most data-intensive follow-up to publications led by Estonian scientists in the field of global fungal biodiversity and endangerment.

This research represents a major advance in global underground biodiversity mapping and demonstrates how machine learning can integrate vast ecological datasets to uncover hidden patterns in Earth’s living systems.

"These maps are more than scientific tools—they can help guide the future of conservation," said Michael Van Nuland, SPUN’s Lead Data Scientist. "Food security, water cycles, and climate resilience all depend on safeguarding these underground ecosystems."

Implications for conservation and policy

The authors emphasize the importance of incorporating underground ecosystems into national and international biodiversity targets. These findings can help guide the design of new protected areas, restoration projects, and climate adaptation strategies that account for belowground biodiversity.

The maps provide a baseline for researchers, policymakers, and conservation practitioners to identify priority areas for action and assess the resilience of ecosystems from the ground up.

The research, published on July 23, 2025 in the journal Nature, marks the first large-scale scientific application of the global mapping initiative launched by the Society for the Protection of Underground Networks (SPUN) in 2021. This effort brings together SPUN, GlobalFungi, GlobalAMFungi, Fungi Foundation, and the Global Soil Mycobiome consortium and researchers from around the world to reveal patterns of fungal richness and rarity across biomes—from the Amazon to the Arctic and marks a major breakthrough in how we understand and visualize life beneath our feet.