Assumed audience
General adult who has completed Fungal Ecology.
The wood wide web
Mycorrhizal fungi don’t just connect to one plant — they connect many plants, often of different species, into a shared network. A single fungal mycelium can associate with multiple root systems simultaneously, creating an underground web of connections that spans the forest floor. See Mycelial Networks for the broader concept.
What flows through the network
Carbon (sugars), phosphorus, nitrogen, water, and signaling molecules all move through mycorrhizal networks, carried by cytoplasmic streaming through the fungal hyphae. A shaded tree can receive carbon from sunlit neighbors. A tree under pathogen attack can send chemical warning signals to connected trees, prompting them to upregulate their own defenses before the pathogen arrives.
Hub trees
Large, old trees (“mother trees”) tend to be the most connected nodes in mycorrhizal networks. They are linked to the greatest number of neighboring trees and fungal partners. Hub trees preferentially channel resources to seedlings, especially their own offspring, supporting the next generation of forest growth through the underground network.
Not always cooperative
Mycorrhizal networks can also be channels for competition. Some plants exploit the network, taking more than they give. Some fungi are parasitic rather than mutualistic. The network is not inherently altruistic — it is a relational infrastructure through which diverse strategies play out. Cooperation and exploitation coexist in the same system.
Implications for forestry and conservation
Clear-cutting severs mycorrhizal networks. Replanting monocultures without appropriate fungal inoculation produces forests with impoverished underground connectivity. Understanding these networks has practical implications for sustainable forestry: retaining hub trees during selective logging, preserving soil integrity, and inoculating seedlings with appropriate mycorrhizal fungi can all improve forest regeneration outcomes.
Why this matters
Mycorrhizal networks reveal that a forest is not a collection of independent trees but an interconnected system. This changes how we think about forest management, conservation, and the nature of biological individuality.