Mapping the global distribution of ericoid mycorrhizal fungi (ErM)
spun authors
summary
Ericoid mycorrhizal fungi are the dominant underground partners of northern heathlands and tundra ecosystems. Their global distribution differs markedly from other mycorrhizal groups, and climate change threatens to reduce their diversity in some of Earth's most carbon-rich landscapes.
Ericoid mycorrhizal fungi are most diverse in the world's northern tundra and boreal ecosystems, where they help plants survive in harsh, nutrient-poor environments and are closely linked to soil carbon storage. Climate change is projected to reduce their diversity across much of their current range, with potential consequences for high-latitude ecosystems and global carbon cycling.
Tiny fungi living on the roots of plants like heathers, blueberries, and rhododendrons help these plants survive in cold, acidic, and nutrient-poor soils. This study created the first global map showing where these ericoid mycorrhizal fungi occur and what controls their distribution.
The researchers found that these fungi are most diverse in northern tundra and boreal forests rather than in tropical regions. Unlike many other organisms, they become more common as you move toward the Arctic. Soil acidity and climate were far more important than the abundance of their host plants in determining where they occur.
The study also showed that these fungi are closely associated with soils that contain large amounts of carbon. However, climate change is expected to reduce their diversity and abundance across many northern ecosystems over the coming decades. Protecting these hidden fungal communities may therefore be important not only for biodiversity, but also for maintaining some of the world's largest natural carbon stores.
Ericoid mycorrhizal (ErM) fungi form symbiotic relationships with plants in the Ericaceae family, including heathers, blueberries, cranberries, and rhododendrons. These fungi enable their hosts to thrive in nutrient-poor, acidic soils by helping them acquire nitrogen and phosphorus from complex organic matter. Despite their ecological importance in boreal forests, tundra, and heathlands, the global distribution of ErM fungi has remained poorly understood compared with arbuscular (AM) and ectomycorrhizal (EcM) fungi. This study provides the first comprehensive global assessment of ErM fungal biogeography.
The study aimed to:
- Map the global distribution of ericoid mycorrhizal fungi.
- Identify environmental factors driving ErM fungal diversity and abundance.
- Examine relationships between ErM fungi, host plants, and soil organic carbon.
- Predict how climate change may alter ErM fungal distributions during the coming decades.
The researchers analyzed 39,163 soil samples collected from 551 independent studies contained within the GlobalFungi Database.
Using more than 13 million fungal DNA sequences, they modelled:
- Global species richness,
- Relative abundance,
- Community composition, and
- Future distributions under the SSP370 climate scenario (2041–2070).
The models incorporated climate variables, soil chemistry, and the abundance of ericoid vegetation to identify the major drivers of fungal distributions.
Implications
The study fills a major knowledge gap by providing the first global map of ericoid mycorrhizal fungi. Together with recent global analyses of AM and EcM fungi, it demonstrates that the three major mycorrhizal groups each have distinct biodiversity hotspots.
This means that protecting belowground biodiversity will require conserving multiple ecosystem types, rather than relying on a single conservation strategy.
The projected decline of ErM fungi under climate change is particularly concerning because these fungi dominate ecosystems that store enormous amounts of soil carbon. Losses of ErM fungi could therefore influence nutrient cycling, vegetation dynamics, and long-term carbon storage in boreal forests and tundra.
