Nature
PUBLISHED
Last year, a paper was published describing the electrical behavior of trees during an eclipse that might be considered the epitome of “huge if true”. The authors claimed to identify an alignment in electrical activity between three spruce trees during the partial solar eclipse of October 2022. Although the study was published in a respected scientific journal, that’s just the start of true peer review, and an assessment by experts has found some big problems with the claim.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.In recent years, reports of electrical communication and sharing of resources between plants and fungi in forests have created great excitement online, with the phenomenon dubbed the "Wood Wide Web". Many claims remain highly contested, with some scientists disputing the phenomenon exists at all, while others argue a real phenomenon is being exaggerated beyond what can be substantiated.
Last year’s paper was perhaps the most extraordinary claim made for tree-to-tree communication in a scientific journal. The suggestion that electrical signals between the trees increased and synchronized in response to the eclipse was surprising enough, but Dr Alessandro Chiolerio and co-authors went further. They presented evidence that electrical activity surged before the eclipse was even under way.
If, as the authors argued, this was more than coincidence, it would require imply trees have a knowledge of the motion of the Moon and Sun humanity only acquired relatively recently. Alternatively, the findings might be explained by long-distance inter-species communication from places where the eclipse started earlier.
The claims attracted considerable publicity, much of it quite uncritical, although other scientists showed plenty of skepticism. As we noted at the time, “Claims this far outside the box will need to be seen many more times to convince most scientists.”
A response to Chiolerio et al’s paper by Professor Ariel Novoplansky of Ben-Gurion University of the Negev and Dr Hezi Yizhaq of The Swiss Institute for Dryland Environmental and Energy Research argues it’s doubtful anything of significance even happened once. “Advancing plant behavior research requires robust experimental design, falsifiable hypotheses, sufficient replication, and stringent controls,” the pair stress, something they clearly think has not happened here.
Novoplansky and Yizhaq start by pointing out that the upsurge in electrical activity by the trees was 14 hours before the eclipse reached the Dolomites, where the study was done, but coincided with a thunderstorm. In fact, lightning strikes were recorded quite close to the trees whose signals were measured, offering a much more plausible explanation for the suddenly chattering trees.
Novoplansky didn’t hold back in his criticism. “To me, this paper represents the encroachment of pseudoscience into the heart of biological research,” he said in a statement. “Instead of considering simpler, well-documented environmental factors, like a heavy rainstorm and a cluster of nearby lightning strikes, the authors leaned into the more seductive idea that the trees were anticipating the impending solar eclipse.”
Novoplansky and Yizhaq also noted some other objections to the claim. Total solar eclipses represent something quite unusual for ecosystems – a burst of night in the middle of the day. However, shallow partial solar eclipses like this one are barely distinguishable from a bit of cloud.
“The eclipse only reduced light by about [an average of] 10.5 percent for two short hours, during which the level of sunlight was approximately twice what the trees could practically use,” Novoplansky said.
Chiolerio and co-authors speculated that the trees might have been responding to gravitational influences, rather than loss of light itself. The Sun and Moon’s gravitational fields are aligned during a solar eclipse, but Novoplansky and Yizhaq note that similar alignments occur every new Moon, and are only slightly closer during an eclipse.
They did not add, but could have, that the increase in the Moon’s gravitational pull when it is at the closest part of its orbit is greater than any additional effect from an eclipse compared to a typical new Moon.
Even without considering all these things, the fact that data was collected from just three living trees and five tree stumps should offer a warning that the extraordinary claims were highly dubious. Co-launching a documentary with the scientific paper didn’t add to the credibility.
“The electrical activity of trees is a real phenomenon but it’s still a nascent field of inquiry,” Novoplansky said. “The idea that variations in electrical signals, observable even in dead logs, might encode memory, anticipation, or collective responsiveness requires a few extraordinary leaps, none of which were supported in the study. The forest is wondrous enough without inventing irrational yet superficially fantastic claims of anticipatory responsiveness or communication based only on correlation.”
The criticism is published in Trends In Plant Science.
