If you think that forests are crisscrossed with underground networks allowing trees to feed their young descendants or to alert them to pest attacks, you have probably been misled by misguided extensionists, or overenthusiastic scientists. . This is the conclusion of a study published in Nature Ecology & Evolution on February 13, which examines several oft-publicized claims regarding mycorrhizal networks, results of the symbiotic association between filamentous fungi and tree roots.
Justine Karst (university of Alberta, Edmonton), Melanie Jones (University of British Columbia) and Jason Hoeksema (University of Mississippi). What these researchers wanted to verify is the existence of other functions supposedly fulfilled by these underground networks.
After reviewing the scientific literature, they believe that their real extent is poorly documented in the field and that certain roles attributed to them, particularly in terms of helping young shoots, are “insufficiently substantiated” – the evidence may even be completely absent. Justine Karst and her colleagues believe that over time scientists have shown an increasingly biased view of these studies, tending to “overestimating the results and ignoring confounding factors in order to promote the beneficial effects of these networks in forests”.
This idea that trees – including of different species – could communicate with each other and pool resources underground is rooted in particular in a study published by the journal Nature in 1997, and presented in “one” under the title “Wood-Wide-Web”. Using radioactive markers, Suzanne Simard, professor of forest ecology at the University of British Columbia, showed for the first time in a controlled manner in the field bidirectional carbon transfers between birches and Douglas firs, likely to benefit shrubs whose photosynthetic capacities were diminished by the shade of their elders.
“Network crooks”
Since then, the notion of cooperation between trees – which goes against Darwin’s view of competition for light, water and nutrients – has flourished. It is featured in bestsellers like The Secret Life of Trees by Peter Wohlleben (Les Arènes, 2017), in a number of documentaries, or TED conferences, such as that of Suzanne Simard. Entitled “How trees talk to each other”, it has been viewed 5.5 million times.
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