Last year, a team of scientists presented evidence that spruce trees in Italy’s Dolomite mountains synchronized their bioelectrical activity in anticipation of a partial solar eclipse—a potentially exciting new insight into the complexities of plant communication. The findings naturally generated media interest and even inspired a documentary. But the claims drew sharp criticism from other researchers in the field, with some questioning whether the paper should even have been published. Those initial misgivings are outlined in more detail in a new critique published in the journal Trends in Plant Science.
For the original paper, Alessandro Chiolerio, a physicist at the Italian Institute of Technology, collaborated with plant ecologist Monica Gagliano of Southern Cross University and several others conducting field work in the Costa Bocche forest in the Dolomites. They essentially created an EKG for trees, attaching electrodes to three spruce trees (ranging in age from 20 to 70 years) and five tree stumps in the forest.
Those sensors recorded a marked increase in bioelectrical activity during a partial solar eclipse on October 22, 2022. The activity peaked mid-eclipse and faded away in its aftermath. Chiolerio et al. interpreted this spike in activity as a coordinated response among the trees to the darkened conditions brought on by the eclipse. And older trees’ electrical activity spiked earlier and more strongly than the younger trees, which Chiolerio et al. felt was suggestive of trees developing response mechanisms—a kind of memory captured in associated gravitational effects. Older trees might even transmit this knowledge to younger trees, the authors suggested, based on the detection of bioelectrical waves traveling between the trees.