The mutual aid between trees by a network of fungi is questioned

A critical analysis of the use of anthropomorphism, the tendency to attribute human characteristics to beings and things.

This western redcedar is the tallest in Stanley Park, Vancouver.

A network of underground fungi that allow trees to communicate and help each other is sparking a buzz in popular culture, but three scientists say the evidence they've reviewed doesn't support that claim.

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We have found, in reviewing the [scientific] literature, that the results of experiments are so variable that it is premature to draw conclusions, says biologist Melanie Jones and professor at the University of British Columbia Okanagan and co-author of the analysis published in the journal Nature Ecology & Evolution (in English).

The authors particularly criticize the statements of Suzanne Simard, one of the leading figures in studies of mycorrhizal networks and professor of forest ecology at the University of British Columbia.

Suzanne Simard, however, defends her work by explaining that the analysis constitutes reductionism, because it is important to consider all the parts of an ecosystem, all the relationships in the forest: the networks in the ground, but also how the trees are related to each other, including all plants and animals, lichens and mosses.

Suzanne Simard searches for a fungal web in the Malcolm Knapp Research Forest, Maple Ridge , British Columbia.

There is insufficient evidence to say that these networks of fungi are widespread, however, believes Justine Karst, associate professor at the University of Alberta and lead author of the study, because only two types of forests have been studied: forests of Douglas firs and a forest in Japan.

The importance of mycorrhizal fungi for plants is not disputed by the study, underlines the specialist. We don't know who is connected to whom in the forest, however, and we certainly don't have a good idea of ​​the extent of these mycorrhizal networks, she says.

Mesh bags are installed around the trees for a field experience.

Simon Joly, a scientist not related to analysis and who is director of the Plant Biology Research Institute at the University of Montreal, says this debate is important for improving research: I think there's a lot of evidence that plants can communicate with each other through these mycorrhizal networks, so fungi, but to say plants will really help each other is another step .

We found that there is actually no conclusive evidence that resources move through this mycorrhizal network. […] They seem to move through the soil solution [the ion-laden groundwater circulating in the soil] and in very small quantities, says Justine Karst.< /p>

For her part, Suzanne Simard believes there is no doubt that resources are shared through multiple pathways: the mycorrhizal network, the mycorrhizal roots and the soil. It really makes sense that trees have multiple ways to interact, multiple paths to share resources or even compete for resources, she says.

Suzanne Simard and Melanie Jones are among the authors of a study published in 1997 which revealed the existence of a network of fungi allowing the exchange of carbon between trees.

The forest ecology professor also published a book in 2022 titled In Search of the Mother Tree : discover the wisdom of the forest. These trees, which she calls mother trees, would be able to help the young shoots so that they receive enough nutrients and carbon sources.

In her research, she says she has demonstrated that even a small transfer of resources from one plant to another through this network could make the difference between life and death, especially in difficult climatic conditions. An assertion that the analysis of the three authors calls into question.

We did not find any peer-reviewed studies in forests to support this claim. [The privileged communication with offspring hypothesis] has therefore not been tested in forests, says the analysis' lead author, Justine Karst.

Research on the communication between trees and their seedlings in the forest is ongoing, says Suzanne Simard.

She cites two laboratory studies by collaborators, including one published in the journal Plant, Cell & Environment, that demonstrate tree recognition of their progeny: We found that carbon moved preferentially to their nearby progeny.

The old-growth forest near Revelstoke, British Columbia is prized by the logging industry.

The analysis criticizes the use of anthropomorphism, the tendency to attribute human characteristics to beings and things. When we personify trees and fungi, we put blinders on in terms of observing and understanding what is really going on, laments Justine Karst, lead author of the analysis.

Simon Joly, director of the Plant Biology Research Institute at the University of Montreal, urges caution when communicating scientific results, as these can be overinterpreted: People want it to look good. They therefore tend to talk more about the good sides and sometimes omit the results that are less positive.

Suzanne Simard does not regret making a comparison between the forest and the human.

“Scientists are meant to be objective, distant observers of the environment. Essentially, it's removing ourselves from nature, as if we're not a part of it, when what we do has a big impact on the forests.

— Suzanne Simard, Professor of Forest Ecology, University of British Columbia

The urgency of the environmental crisis forces us to act quickly, says the professor of forest ecology: The fact is that we are already doing things without having evidence, we are clear-cutting all over the world. […] Needing more research before acting is actually not serving society, when we are in a crisis like this.

Lack of evidence equates to misinformation for Justine Karst, which has no place in discussions when it comes to making these very important decisions about the future of our forests, she says.