37 Mushrooms and a Forest Internet: Electrical Information Flows in a Mycorrhizal Network

Forum topic · ✨步子哥 · 2026-09-07

Summary

A field experiment by Yu Fukasawa and colleagues, published in Scientific Reports (2026), recorded electrical potentials from 37 ammonia-fungus sporocarps (29 Hebeloma danicum, 8 Hebeloma cylindrosporum) in a Japanese oak forest using needle electrodes and a Granger causality analysis. The study found that electrical information flows across mushrooms even between different genetic individuals and species, apparently propagating through soil ion gradients. Information flow decayed with both genetic and spatial distance. Most strikingly, watering a single mushroom increased information flow across the network, while uniformly spraying the entire plot reduced it—an apparent demonstration of information-theoretic redundancy elimination: when every node already knows the same thing, there is nothing to communicate. In contrast, applying urine (a nitrogen-rich signal the ammonia fungi had already been primed for) changed information flow the least, showing the network responds to 'news' rather than any generic disturbance. The findings suggest fungal networks function not just as resource pipelines ('Wood Wide Web') but as genuine information networks, echoing distributed communication principles that AI systems re-engineer today.

Overview

In October 2022, Yu Fukasawa's team instrumented 37 mushrooms (29 *Hebeloma danicum*, 8 *Hebeloma cylindrosporum*) in a secondary mixed forest in Kami, Miyazaki, Japan, with 37 pairs of subcutaneous needle electrodes (one on the cap, one at the stem base), recording voltage once per second (±100 mV) for 3.5 days using a GRAPHTEC GL840-Midi logger. The mushrooms had been induced six months earlier by applying urea (640 g/m²), which activates 'ammonia fungi.'

The results, published 2 March 2026 in *Scientific Reports*, show that electrical signals carry information between mushrooms in ways that follow information theory.

Key points

Information flow crosses clone and species boundaries. Granger causality analysis of pairwise voltage series revealed significant information flow even between genetically distinct individuals and between species, suggesting signals propagate through soil (e.g., ion gradient changes) rather than only along a single mycelial network.
Signal decay follows genetic and spatial distance. Cross-species flow was weaker than same-species; cross-clone weaker than same-clone; strength fell with distance. This structured decay argues against mere synchronized response to environmental factors.
Localized vs. global watering produced opposite effects. Pouring 200 ml of water at one mushroom's root (#1) *increased* average network information flow; spraying 10 L/m² over the whole plot *decreased* it dramatically.
The redundancy-elimination interpretation. As Fukasawa put it: "Applying water to all the mushrooms may mean that there's no need to share information since the whole network already knows what's going on." When every node already knows the same fact, information value drops to zero and the network goes quiet—a natural emergence of a core information-theoretic principle.
The urine control. The team also applied 200 ml of human urine locally. This produced the *smallest* change in information flow: the ammonia fungi were already in a nitrogen-rich state after urea induction, so urine was 'old news' rather than news. Distinguishing 'news' (water) from 'old news' (urine) separates genuine communication from generic physical response to disturbance.

Context: mushroom electrophysiology

Fungi have no nervous system, but mycelia generate analog (gradual, millivolt-scale) electrical potentials from ion channel activity—physically similar to neuronal action potentials but graded rather than all-or-none. In 2022, Andrew Adamatzky (University of the West of England) recorded 24 hours of spiking from four fungal species (*Omphalotus nidiformis*, *Flammulina velutipes*, *Schizophyllum commune*, *Cordyceps militaris*) and found vocabularies of 14–50 spike 'words' with inter-spike interval distributions statistically similar to human language (*Royal Society Open Science*). Fukasawa's work goes further by testing whether signals actually convey information between individuals.

Implications

The study strengthens the case that the 'Wood Wide Web' is not merely passive resource diffusion but an active information network, with distance decay, cross-node propagation, and redundancy-based bandwidth modulation.
The network behavior statistically mirrors intentional communication systems—sender and receiver benefit from exchanging information the other lacks—without any brain or designer, in a self-organizing system ~400 million years old.
The author draws a metaphor for AI-era distributed systems: federated learning, AllReduce, and multi-agent protocols reinvent redundancy elimination that fungal networks have long optimized. The elegant lesson: when all nodes know everything, the network falls silent—and that silence is efficiency, not failure.

References

1. Fukasawa, Y., Akai, D., Takehi, T., Takahashi, D., & Osada, Y. (2026). Electrical information flows across the sporocarps of two ectomycorrhizal fungi in the field. *Scientific Reports*. DOI: 10.1038/s41598-026-42673-y 2. Adamatzky, A. (2022). Language of fungi derived from their electrical spiking activity. *Royal Society Open Science*, 9(4), 211926. DOI: 10.1098/rsos.211926 3. Fukasawa, Y., et al. (2023). Mushroom's electrical conversation after the rain. *SSRN Electronic Journal*.