When lightning strikes a tree in the tropics, the whole forest explodes.
“At their most extreme, it kind of looks like a bomb went off,” said Evan Gora, a forest ecologist at the Cary Institute of Ecosystem Studies in Millbrook, N.Y. Dozens of trees around the one that was struck are electrocuted. Within months, a sizable circle of forest can wither away.
Somehow, a single survivor stands, seemingly healthier than ever. A new study by Dr. Gora, published last week in the journal New Phytologist, reveals that some of the biggest trees in a rainforest don’t just survive lightning strikes. They thrive.
The rainforest in Panama’s Barro Colorado Nature Monument is the perfect place to study whether some trees are immune to lightning. It’s home to the Smithsonian Tropical Research Institute and one of the most closely studied tropical forests in the world. Dr. Gora set out to study whether individual trees in the forest benefit from being struck by lightning. And if they did, does that help the population of the species survive at a larger scale?
Early on, he spent much of his time climbing trees, looking for signs of lightning damage. But making critical observations could be painfully inefficient. Dr. Gora would begin climbing one tree, convinced it was the struck trunk, only to get 50 feet up and see he actually wanted to be up the neighboring tree. Honey bees would also swarm Dr. Gora’s eyes and ears.
“Your entire life is just buzzing,” he said. “It’s horrifying.”
Dr. Gora needed a more efficient way to find struck trees, so he and his collaborators developed a method for monitoring lightning strikes and triangulating their electromagnetic signals. The technique led him more quickly to the right tree, which he could assess using a drone.
From 2014 to 2019, the system captured 94 lightning strikes on trees. Dr. Gora and his team visited sites to see which species had been struck. They were looking for dead trees as well as “flashover points,” where leaves are singed as lightning jumps between trees. From there, the canopy dies back, and the tree eventually dies.
Eighty-five species had been struck and seven survived, but one stood out literally and figuratively: Dipteryx oleifera, a towering species that had been struck nine times, including one tree that had been hit twice and seemed more vigorous. D. oleifera stands about 30 percent taller than the rest of the trees and has a crown about 50 percent larger than others, almost as if it is an arboreal lightning rod.
“It seems to have an architecture that is potentially selecting to be struck more often,” Dr. Gora said.
All the struck D. oleifera trees survived lightning strikes, but 64 percent of other species died within two years. Trees surrounding D. oleifera were 48 percent more likely to die after a lightning strike than those around other species. In one notable die-off, a single strike killed 57 trees around D. oleifera “while the central tree is just happy and healthy,” Dr. Gora said. Lightning also blasted parasitic vines off D. oleifera trees.
The clearing of neighboring trees and choking vines meant struck D. oleifera trees had less competition for light, making it easier to grow and produce more seeds. Computer models estimated that getting struck multiple times could extend the life of a D. oleifera tree by almost 300 years.
Before the study, “it seemed impossible that lightning could be a good thing for the trees,” Dr. Gora said. But the evidence suggests that D. oleifera benefits from each jolt.
“Trees are in constant competition with each other, and you just need an edge relative to whatever is surrounding you,” said Gabriel Arellano, a forest ecologist at the University of Michigan who was not involved in the study.
The physical mechanisms that help trees survive intense lightning strikes remain unknown. Different trees could be more conductive or have architectures that escape damage, Dr. Gora suggested.
While the study was only in Panama, similar patterns have been observed in other tropical forests. “It’s remarkably common,” said Adriane Esquivel Muelbert, a forest ecologist at the University of Birmingham in England who had collaborated with Dr. Gora but was not involved in the study. “It’s quite clear when it happens.”
Climate change is set to increase the frequency and severity of thunderstorms in the tropics. Some trees, it seems, may be better equipped for a stormy future than others.
