Are trees talking underground? For scientists, it’s in dispute

GABRIEL POPKIN

CHENNAI: Justine Karst, a mycologist at the University of Alberta, feared things had gone too far when her son got home from eighth grade and told her he had learned that trees could talk to each other through underground networks.

Her colleague, Jason Hoeksema of the University of Mississippi, had a similar feeling when watching an episode of “Ted Lasso” in which one soccer coach told another that trees in a forest cooperated rather than competed for resources.

Few recent scientific discoveries have captured the public’s imagination quite like the wood-wide web — a wispy network of fungal filaments hypothesised to shuttle nutrients and information through the soil and to help forests thrive. The idea sprouted in the late 1990s from studies showing that sugars and nutrients can flow underground between trees. In a few forests, researchers have traced fungi from the roots of one tree to those of others, suggesting that mycelial threads could be providing conduits between trees.

These findings have challenged the conventional view of forests as a mere population of trees: Trees and fungi are, in fact, coequal players on the ecological stage, scientists say. Without both, forests as we know them wouldn’t exist.

Scientists and non-scientists alike have drawn grand and sweeping conclusions from this research. They have posited that shared fungal networks are ubiquitous in forests around the world, that they help trees talk to each other and, as Coach Beard on “Ted Lasso” articulated, that they make forests fundamentally cooperative places, with trees and fungi united in common purpose — a dramatic departure from the usual Darwinian picture of interspecies competition. The concept has been featured in numerous media reports, TV shows and bestselling books, including a Pulitzer Prize winner. It even shows up in “Avatar,” the highest-grossing movie of all time.

And the theory could be starting to influence what happens in real forests. Some scientists, for example, have suggested managing forests explicitly to protect fungal networks. But as the wood-wide web has gained fame, it has also inspired a backlash among scientists. In a recent review of published research, Karst, Hoeksema and Melanie Jones, a biologist at the University of British Columbia, Okanagan, found little evidence that shared fungal networks help trees to communicate, swap resources or thrive. Indeed, the trio said, scientists have yet to show that these webs are widespread or ecologically significant in forests.

For some of their peers, such a reality check is long overdue. “I think this is a very timely talk,” said Kabir Peay, a mycologist at Stanford University, about a presentation Karst recently gave. He hoped it could “reorient the field.”

Others, however, maintain that the wood-wide web is on firm ground and are confident that further research will confirm many of the hypotheses proffered about fungi in forests. Colin Averill, a mycologist at ETH Zurich, said that the evidence Karst marshaled is impressive. But, he added, “the way I interpret the totality of that evidence is completely different.”

Most plant roots are colonised by mycorrhizal fungi, forming one of Earth’s most widespread symbioses. The fungi gather water and nutrients from the soil; they then swap some of these treasures with plants in exchange for sugars and other carbon-containing molecules.

Popkin is a journalist with NYT©2022

The New York Times