Suzanne Simard is a Canadian forest ecologist who found that trees are linked below ground by the threads of fungi that live on their roots, and that carbon, water, nitrogen and warning signals can pass between trees through these networks, even between different species. She went on to describe the oldest and biggest trees as Mother Trees, hubs linked to many younger trees around them, a claim that other forest scientists dispute and that she and her colleagues have defended. Therapeutic Shamanism, which sees trees as the Standing PeopleStanding People. The Trees. More about this, wisdom keepers and teachers of generosity and cooperation, arrives at its picture of trees by a different road, and the two can be set side by side.
Who is Suzanne Simard? #
A forest ecologist from British Columbia, born in 1960, who grew up in the Monashee Mountains in a family that logged by horse. She worked as a research scientist for the British Columbia Ministry of Forests, took her doctorate at Oregon State University in 1995 with a thesis on carbon moving between tree species, and became a professor of forest ecology at the University of British Columbia.1 Her memoir, Finding the Mother Tree: Uncovering the Wisdom and Intelligence of the Forest (2021), tells the story of thirty years of field and greenhouse experiments alongside her own life, including the death of her brother and her treatment for breast cancer.2
Her early work for the Forest Service started from the policy of the day, which held that young conifer plantations grow best when the native birch, alder and other plants around them are cleared away. Over many replicated trials she found that clearing them often did little or nothing to help the conifers, and in some cases made disease worse.2
What did she find about trees sharing with each other? #
That trees of different species can pass carbon to one another through the fungi that join their roots. Most trees live in partnership with fungi, which wrap or enter their fine roots, take sugars from the tree, and bring back water and nutrients from the soil. One fungus can link the roots of many trees, so a forest floor holds networks of fungal threads connecting tree to tree.
For her doctorate Simard grew paper birch, Douglas fir and western red cedar together, fed the birch and the fir different forms of carbon that could be traced, and then measured where the carbon went. Cedar, which partners with a different kind of fungus and cannot join the same network, showed how much carbon simply leaked through the soil. The carbon moved between birch and fir in both directions, with more going from birch to fir than back, and the more the fir was shaded, the more it received. The paper appeared on the cover of Nature in August 1997, and, in her words, “Nature called my discovery the wood-wide web”.3 Later work by colleagues found that the direction can reverse with the seasons, with fir giving more to birch in spring and autumn.3
Her students then mapped a network in a Douglas fir forest and found that the biggest, oldest trees were linked to almost all the younger trees near them, one of them to forty-seven others. In a later study with potted trees, firs stripped of their needles by insects passed carbon and defence signals to neighbouring pines, but only to pines linked to them through the network.4 On the forest more widely, see Is the living world intelligent?
What are Mother Trees? #
Simard’s name for the old hub trees at the centre of these networks. She coined it in the field, standing amongst old Douglas firs, and wrote, “The hubs were Mother Trees.” She noted at once that each fir carries both male and female cones, so “mother” is not a botanical description, but “it felt like mothering to me. With the elders tending to the young.”5
Her later experiments asked whether Mother Trees favour their own offspring. Seedlings grown from a tree’s own seed and linked into its network survived better and grew bigger than seedlings from strangers, which she called “a strong hint” that the trees could recognise their kin. In the greenhouse, young trees sent more carbon to the fungi of related seedlings than of unrelated ones, and more still when they were injured. She is open about the limits. In some families the parent tree gave as much to strangers as to kin, and she could not show that the carbon reaching the fungi helped the seedlings: “We didn’t know if the fungus kept the carbon for itself, like a middleman”.6 She also says that, explaining her work to children, she chose words such as “mother”, “her” and “children”, knowing that scientists would criticise them.6
The name had been used before her. A Secwepemc elder, Mary Thomas, whose people traditionally lived by hunting, fishing and trading, already called the birches Mother Trees, and taught respect for them as equal partners, and Simard says so in her book.7
Is her work disputed? #
Yes. Soon after the 1997 paper, a team of British plant scientists questioned how much of the carbon had really passed through the network and how much through the soil, and whether the method had inflated the result; Simard replied to each point, and the dispute is set out in her book.8
A larger challenge came in 2023, from several critics including the mycologist Justine Karst, with Melanie Jones, a co-author of Simard’s first study, and Jason Hoeksema. Their paper analysed how the early field studies have been cited in well over a thousand later papers, and argued that claims about these networks being widespread, and about older trees feeding seedlings through them, had run ahead of what the experiments show, with later papers often repeating the stronger claims. As reported by the writer Harriet Rix, they found that amongst papers published in 2022, “fewer than half the statements made about the original field studies could be considered accurate”, and that the effect of a shared network on young trees was sometimes harmful, sometimes nil and sometimes helpful.9
Simard, with Teresa Ryan and David Perry, replied in 2025 to three of these critiques together. They answered that there are multiple lines of evidence for the networks, that their effects depend on the kind of forest and the conditions, and that researchers routinely and justifiably combine field work with laboratory and greenhouse studies. Of the ‘mother tree hypothesis’ tested by one group of critics, they wrote that it had been invented from the metaphor used in her memoir.10
How does her work sit with Therapeutic Shamanism? #
Side by side, though the two start from different places. Simard works from measurement in the middle-worldMiddle-world. Ordinary physical reality together with its energetic layers: the realm of individuality, separation and mixed intentions, and the only realm where harm is possible. “If there is a hell, then it is the middle-world.” Read the full answer and mostly speaks of a network of individual trees. Therapeutic Shamanism works from shamanic experience, and sees trees as the Standing People, part of the Plant People, with a highly collective awareness that is shared across a whole species. Because they live so long, individual trees also gather a history and a character of their own, and the older a tree is, the more individual consciousness it acquires.11
Within that picture, trees are generous by nature. Each provides shade, shelter and food for dozens or even hundreds of other species, a community in itself, so the Standing People are teachers of generosity, selfless giving, cooperation, and how to create and protect communities. Their long lives make them wisdom keepers and the historians of the community, and great teachers of Eldership.11 Plants cooperate too. They warn each other about insect or fungal attack, and send nutrients along their roots and the mycelium fungal network to help neighbours who are struggling.12 Simard’s old trees linked to the young, which she herself describes as elders tending to the young, can be set beside this teaching, though she reached them by a different road. See What are Plant People, and what gifts do they bring? and What is an Elder?
Simard’s book also comes back to equality. Following Mary Thomas, she writes that the word ‘equal’ is where Western philosophy stumbles. Finding Your Deep Soul has a short exercise in non-hierarchical thinking, which asks the reader to feel what it would be like to see all animals and plants as having equal status to humans.13 See What is the myth of human supremacy?
