Underground fungal networks are long enough to reach beyond the Solar System
Hyphae thinner than a centimetre go unnoticed because they go unseen; but a new calculation puts their total length beyond the edges of the Solar System. Ars Technica reports on the study, which gives a hard global figure to the reach of mycorrhizal networks.
Mycorrhiza is a symbiotic relationship between plant roots and fungi. The fungi supply the plant with phosphorus, nitrogen and trace elements; in return, the plant feeds the fungi sugars produced by photosynthesis. The partnership has been a fundamental component of the roughly 450-million-year history of land plants.
The study's headline number is striking: the total length of all mycorrhizal hyphae in land ecosystems is about 450 quadrillion kilometres. That is a distance that exceeds the position of Voyager 1 from Earth many times over. The figure describes an infrastructure that is "long but narrow" because the hyphae are extremely thin.
The infrastructure matters for the global carbon cycle. Mycorrhizae capture close to a third of atmospheric carbon underground. That "carbon sink" function has become an additional parameter in climate modelling. The balance between soil-emitted and soil-absorbed carbon is directly related to fungal network health.
Soil health is not just an agriculture question. It bears on water retention, erosion control and biodiversity. The FAO's 2024 soil status report says about a third of global soil health is facing moderate or severe degradation. Disruption of mycorrhizal networks is both cause and consequence of that degradation.
The study's method combines mycorrhizal density measurements from biomes around the world and overlays them into a single map. Tropical rainforests, temperate forests, savannah and tundra each get their own density curve. Results show large differences between biomes, but together they reveal the global scale of total length.
The conservation angle is critical. Tillage, heavy fertilisation and fungicides damage mycorrhizal networks. Conservation agriculture — minimum tillage, cover crops, diversified rotation — helps protect the networks. The latest update of the EU Common Agricultural Policy made soil biological condition one of the payment criteria.
Dispersal is another dimension. Spores spread over long distances through air, raindrops and wildlife. That dispersal is critical for genetic diversity in the networks. Habitat fragmentation narrows the geography spores can reach.
A joint project between Istanbul University's Faculty of Forestry and the Ministry of Agriculture is mapping mycorrhizal profiles across Turkey's diverse forest and agricultural ecosystems. The findings provide reference data for the country's biodiversity policy. Anatolia's varied climate zones make a rich field for mycorrhizal diversity research.
The core message: because it is unseen, the most actively working part of the biosphere is often overlooked. Ars Technica's summary underlines that the underground infrastructure needs more visibility in the sustainability conversation. Over the coming years, climate and agriculture policies are expected to factor these underground networks in more directly. This article is not investment or agricultural advice.
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