FIELD NOTES: Lessons from Fungi

~by Jim Eagleman

Years ago, I struggled through a class in agriculture economics. Supply and demand I understood, but not trading, global reliance, and stock markets. When a botany professor on a walk explained how fungus grows and told us to imagine it as a market economy, “one that was 400 million years old, and so universal that it operates in almost every ecosystem in the world,” his analogy got me thinking.

He said unlike human economics requiring understanding and reasoning to help make decisions, “traders in this market beg, borrow, steal, and cheat all without thought.”

I wanted to know more about this biology, and it took some study. And funny thing: a lesson in one discipline can help you understand another.

I learned that the intertwining plant roots of all kinds of trees, shrubs, and wildflowers, are colonized by the fungus mycorrhizae. Fungus forms these underground, vast, and complex networks. They are tiny filaments, thinner than a strand of cotton, and are connected to multiple plants simultaneously. A tiny underground subway system was another comparison I was to visualize, where each plant root is a station, and resources are loaded and unloaded.

A mushroom poking up through the leaf litter, sometimes colorful and exotic-looking, is not the actual plant, but the fruiting body. As nutrients are absorbed and the fungus grows, sometimes just within minutes, spores develop that can produce more mushrooms. I thought of spores as specialized seeds—tiny, encapsulated, and wind-swept, capable of withstanding droughts, freezing, and time. They grow when conditions are right.

I read of an archaeologic dig at the pyramids where workers excavated gravel from deep within the tunnels. The dirt and stones were carried out daily and dumped outside the pyramid, then covered with a tarp. The work continued for weeks, and one day mushrooms grew on the debris pile. Enough heat, wind or moisture, or combinations, had accumulated, causing spores to grow a new mushroom. They were identified as the same mushrooms that grew locally from spores that were estimated to be 4,500 years old.

He said deals made by plants and fungal partners can be similar to those made by stock market traders. These partners are not exchanging stocks and bonds, they’re exchanging essential resources. For the fungus, that’s sugars and fats. The fungus gets all its carbon from the plant—a lot of carbon from a lot of plants. How much carbon? It’s estimated that each year, roughly five billion tons of carbon from plants go into this underground network. Roots need phosphorus and nitrogen, and get it from exchanging carbon to gain access to all the nutrients collected by the fungal network. This exchange we were to think of as the actual stock exchange of the trade market.

The botany professor must have assumed we knew something about economics. He said we’d soon understand it better. Then he handed out shovels and told us to meet outside. We walked to a forested area off campus and for the next hour we dug a long, deep hole next to trees. This soil profile— cut flat, with clean sides deep into the hillside— was our first glimpse at the underground world of mycelium.

Long, delicate, white threads, called hyphae, clung to the undersides of rotten bark as shovels dug into dirt. Some threads were destroyed by our digging, but enough remained to see their point of attachment. Thick tree roots intertwined with longer ones, thin ones moved up to the surface where tiny feeder roots and the threads touched the bottom of leaves and twigs. Like the subway network, exchange of nutrients, water, and microbes of an infinite amount took place here. An underground world was revealed, and we picked it apart, finding along with the mycelium, buried nuts, earthworm tunnels and discarded insect shells. The lesson from fungi that day was that a lowly, non-chlorophyllic plant, barely visible and appearing sterile, made an impact.

If we think of nature as a series of separate systems, loosely connected except maybe by the same weather, it’s an injustice. From early on, there’s an important lesson in life we observe, then are taught; things work with other things. Interdependencies and relationships exist. And it’s a truism in nature, maybe mystifying at first, but tested by science, retested, then analyzed over time. Those who examine further might stumble upon more connections, other associations not yet known.

“The first law of intelligent tinkering is to save all the parts,” said biologist and author, Aldo Leopold. The essential parts, some subtle, some more noticeable, all work together. When a part goes missing, at some point we notice things aren’t working as well. That missing part may be vital.

The task fungus plays, often overlooked and seemingly insignificant, aids in decomposition, recycling nutrients, and plant communications. It certainly ranks right up there in importance with the green world around us and is a vital part in all ecosystems.

Happy mushrooming this spring.

To inquire about this or other articles, contact the author at: jpeagleman@gmail.com