Suzanne Simard — The Mother Tree

An icebreaker

A forest ecologist showed that fungal threads can link the roots of different trees underground and let carbon move between them. A 2023 review by other researchers found how common and important that sharing really is remains far less settled than the popular story suggests.

Ask one of these · tap to take it

Could trees really be helping each other underground?
How do you turn a striking finding into a citywide idea?
What happens to a scientific finding once it becomes a story?
Would knowing a forest 'cooperates' change how you see one?

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Worth knowing · 1 of 5

What is she known for discovering?

As a forest ecologist, she used radioactive and stable isotopes to trace carbon moving between Douglas fir trees connected by shared fungal networks in the ground, work published starting in the 1990s that helped launch the field of forest-network research.

Worth knowing · 2 of 5

What is a 'mother tree' in her account?

She uses the term for large, older, well-connected trees that she argues are linked to many younger trees through fungal networks and may pass resources toward them, a claim drawn from her field studies of specific forest stands.

Worth knowing · 3 of 5

What did the 2023 review find?

Researchers reviewing the evidence found that only a couple of forest types had actually been studied for these networks, and that results on whether connected seedlings benefit were mixed: some studies found benefit, many did not.

Worth knowing · 4 of 5

Does the review say her core finding is wrong?

No. It confirms that carbon and other resources can move between trees through shared fungal networks in tested cases. What it disputes is how widespread, essential, and one-directional that sharing is across forests generally, beyond the specific sites studied.

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How does she respond to that kind of scrutiny?

She has continued publishing peer-reviewed research and leads a long-running, multi-site project testing how these networks affect forest recovery and regeneration.

Words to know

Mycorrhizal networkAn underground web formed when fungi connect to the roots of multiple trees at once, sometimes linking separate species.

Isotope tracingA method using labeled forms of carbon or other elements to track how a substance moves between organisms.

Mother treeHer term for large, well-connected trees she argues play an outsized role in a forest's shared fungal network.

More words

Citation biasA pattern in which studies supporting a popular claim get cited more often than studies that complicate it.

A voice · 1 of 3

Suzanne Simard · Forest ecologist who led the original research

Using isotope tracing in Douglas fir stands starting in the 1990s, she showed carbon moving between trees through shared fungal networks, and in her 2021 book argued that large 'mother trees' play a central, supportive role within those networks.

A voice · 2 of 3

Justine Karst · Mycorrhizal ecologist who led the 2023 review

Co-authoring a 2023 review in Nature Ecology & Evolution, she found that claims about widespread, beneficial mother-tree networks were supported in only a narrow slice of studied forests, and argued the popular narrative had outpaced the underlying evidence.

A voice · 3 of 3

Melanie Jones · Mycorrhizal researcher and co-author of the 2023 review

As a co-author of the 2023 review, she examined the published field studies and reported that evidence for seedlings benefiting from network access was mixed, pushing back on the assumption that such sharing reliably favors younger trees.

A line to leave them with

The threads carry carbon. How much they carry the forest itself is still being tested.