Forests Have a Secret Underground Web, and Now We Get a Glimpse

Trees are pretty amazing in their own right, but now scientists have found that under every forest is an intricate system of fungal and bacterial branches that creates a wondrous web of connectivity.

Writing in the science journal “Nature“, researchers at the Crowther Lab at ETH Zurich, Switzerland, together with a team from Stanford University in the US, describe how they used data from the Global Forest Initiative to build what they describe as “bottom up” models of the fungal networks beneath our forests. These are made up of fungi that form symbiotic relationships with other lifeforms, in this case trees.

The fungi/tree relationship can have several benefits. For example, phosphorous can be hard to come by in many soils, and trees would need root systems that spread huge ranges in order meet their phosphorous needs. However, fungi can supply that phosphorous and give it over to the trees in exchange for nutrients they need.

By looking at the data from 28,000 tree species spanning 70 different countries, the researchers gained insights into they symbiotic relationships between different trees and different organisms.

For example, oak trees usually partner up with fungi called “ectomycorrhizal fungi“, or EM for short. Maple trees, on the other hand, pair up with “arbuscular mycorrhizal fungi” (AM fungi). The fungi interact with their tree partners in slightly different ways, and in fact they aren’t the only ones who form such relationships. Some trees work with bacterial families to offer up their nutrients in return for those that they can’t easily access on their own.

Critically, this research found that the type of fungi and relationship present beneath those forests seems to depend, at least in part, on the climate.

In cooler climates where boreal forests dominate and the temperatures and types of weather mean that things decay more slowly, EM fungi were far more prevalent. In places like Brazil, where the heat and humidity means matter can break down very quickly, AM fungi tend to rule.

What of the bacteria, though? Well, because bacteria are particularly good at nitrogen fixing, they seem to have found willing partners in very dry, arid conditions where their abilities are useful.

Speaking to the BBC, researcher Thomas Crowther put this finding into perspective. “It’s the first time that we’ve been able to understand the world beneath our feet, but at a global scale,” Crowther said. “Just like an MRI scan of the brain helps us to understand how the brain works, this global map of the fungi beneath the soil helps us to understand how global ecosystems work. What we find is that certain types of microorganisms live in certain parts of the world, and by understanding that we can figure out how to restore different types of ecosystems and also how the climate is changing.”

Particularly interesting was the finding that EM fungi are vulnerable to climate change. At the same time, those same EM fungi are capable of removing and storing carbon. To lose them would be to lose another tool in the fight to keep our climate under control, so there is added interest in monitoring that relationship and trying to cultivate its growth.

The notion of a connected web in our woodlands is interesting in itself, and from a scientific perspective it throws up a wonderful set of questions.

In terms of conservation and land management, it has a few interesting implications. For one thing, we’re used to thinking of woodlands as being made up of individual trees and that, of course, is still true. However, these findings suggest that woodland health may rely not just on the health of individual trees but the wider network beneath. Of course, we would assume this to an extent anyway, but the confirmation provided in these findings gives new insight into just how interdependent our woodland environments might be.

The news of a so-called “Wood-Wide-Web” could also be a major boon to our tree-planting efforts. The UN and global partners are embarking on massive reforestation schemes in the hopes of restoring natural habitats and using trees as natural carbon capture technologies. Now that we can map the fungal and bacterial webs beneath our forests, we can look at what trees are best suited for a particular region and give them the best chance to thrive.

The next time you go walking in the woods, spare a thought for all the life and activity beneath your feet and just how connected all that habitat really is.

Photo credit: Getty Images.

55 comments

Ingrid A
Isabel A13 days ago

Thank you for posting

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Peter B
Peter B23 days ago

TYFS

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Lorraine A

Nature has known how to work together since its conception unlike mankind. We really do need to learn her lessons before its too late.

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niarica lubatti
Past Member 24 days ago

m

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Marija M
Marija Mohoric24 days ago

Rita D. I agree....tks for sharing.

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Rita Delfing
Rita D25 days ago

Funny how humans think we are so intelligent but we are the destroyers of the planet and constantly interfere with nature for our greedy selves, seems nature works together much better and does what's good for the entire forest, we could learn but I doubt we will.

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Peter B
Peter B26 days ago

thank you

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Renata B
Renata B26 days ago

Research the Pando: it's amazing. It's a clonal colony of quivering aspens. If you read the story you will be enchanted. Like the Lord of the Rings.

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Lorraine Andersen

All life is amazing. I have a feeling we don't even know the half of it!!

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Chad Anderson
Chad A27 days ago

Nice.

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