Getting hit by lightning is good for some tropical trees

(Press-News.org) Getting zapped with millions of volts of electricity may not sound like a healthy activity, but for some trees, it is. A new study, published in New Phytologist, reports that some tropical tree species are not only able to tolerate lightning strikes, but benefit from them. The trees may have even evolved to act as lightning rods.

The research was led by Evan Gora, a forest ecologist at Cary Institute of Ecosystem Studies. Gora studies how lightning impacts biodiversity and carbon storage in Panama’s tropical forests. 

Lightning kills hundreds of millions of trees per year. But in 2015, while working in Panama, Gora and his colleagues came across a Dipteryx oleifera tree that had survived a strike with little damage — even though the jolt had been strong enough to blast a parasitic vine out of its crown and kill more than a dozen neighboring trees.  

“Seeing that there are trees that get struck by lightning and they’re fine was just mind-blowing,” Gora recalled. Over time, the team encountered other Dipteryx oleifera trees thriving after getting hit, so they decided to take a closer look.

Scientists had previously suspected that some trees evolved to tolerate lightning, but evidence to back it up was lacking. In 2022, Gora and colleagues demonstrated for the first time that trees differ in their ability to survive getting hit by lightning. Their new paper, published Wednesday, is the first to show that trees can benefit from these electric jolts. 

Using a unique lightning location system, the team tracked the outcomes of 93 trees that had been struck by lightning in Barro Colorado Nature Monument in central Panama. For two to six years after the strike, the team measured tree survival rates, crown and trunk condition, number of parasitic vines or lianas, and neighboring tree mortality. The study included nine directly struck Dipteryx oleifera trees, and compared them with 84 other trees that had been struck. 

All nine Dipteryx trees survived direct lightning strikes with only minor damages. In contrast, directly struck trees of other species were badly damaged, losing 5.7 times more leaves from their crowns, and 64% died within two years. 

When each Dipteryx tree was zapped, an average of 9.2 neighboring trees were killed as the electricity traveled between adjoining vines and touching branches, or jumped across small gaps between trees. Lightning strikes also reduced Dipteryx liana infestations by 78%, freeing trees from some of the pressure these parasitic vines have on light and nutrient availability.

These patterns also bore out across the broader population. The team found that Dipteryx trees tend to have fewer lianas. Analyzing trends in tree death over the past 40 years, the researchers found that the trees neighboring Dipteryx trees were 48% more apt to die than other trees in the forest, likely because of lightning. 

Using drones, Gora and colleagues created 3D models of canopy height, which showed that Dipteryx trees tend to be about four meters taller than their nearest neighbors, likely because lightning killed their taller neighbors, giving them an advantage in competing for light and space. 

“These data provide the first evidence that some trees benefit from being struck by lightning,” the authors write. Or, as Gora puts it, “It's better off for a Dipteryx oleifera tree to be struck than not.”

Because of all these benefits, Dipteryx oleifera trees may be specially adapted to attract lightning. With their distinctive height and unusually wide crowns, they may be up to 68% more likely to get electrocuted than other trees with average height and crowns, according to the team’s calculations. 

Estimates suggest individual Dipteryx oleifera trees are directly hit by lightning every 56 years, on average. And since the trees can live for hundreds or possibly more than a thousand years, they are expected to survive these blasts many times throughout their lives. During the study, one of the Dipteryx trees was struck twice in just five years. 

The remarkable ability to survive lightning strikes and benefit from the removal of lianas and competitors gives Dipteryx trees a major advantage over other trees. According to the scientists' calculations, lightning tolerance boosts the species’ ability to produce offspring by 14 times. 

Next, the team aims to investigate what electrical or structural traits allow these trees to survive lightning strikes. They would also like to explore whether other species show lightning tolerance, to better understand how common this phenomenon is. 

What is clear is that lightning plays an underappreciated role in tree competition. And with lightning on the rise in many regions due to climate change, its influence may increase, potentially favoring lightning-tolerant species like Dipteryx oleifera. Understanding lightning and its role in shaping forests may be important for predicting changes in biodiversity and carbon storage, and for informing tropical reforestation efforts. 

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Study co-authors include: Helene Muller-Landau and Pablo Narváez of the Smithsonian Tropical Research Institute; KC Cushman of Oak Ridge National Laboratory; Jeannine Richards of Florida Gulf Coast University; Phillip Bitzer and Jeffrey Burchfield of the University of Alabama in Huntsville; and Stephen Yanoviak of the University of Louisville.

This work was supported by grants from the National Science Foundation (DEB-1354060, DEB-1655346, and DEB-2213246 to SPY, DEB-1354510, DEB-1655554, and DEB-2213247 to PMB, and DEB-2213245, DEB-2241507, and GRF-2015188266 to EMG), the National Geographic Society (9703-15 to EMG), and a Smithsonian Tropical Research Institute Tupper Postdoctoral Fellowship to EMG. KCC was supported as part of the Next Generation Ecosystem Experiments-Tropics, funded by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research.

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Cary Institute of Ecosystem Studies is an independent nonprofit center for environmental research. Since 1983, our scientists have been investigating the complex interactions that govern the natural world and the impacts of climate change on these systems. Our findings lead to more effective resource management, policy actions, and environmental literacy. Staff are global experts in the ecology of: cities, disease, forests, soils, and freshwater.

New Phytologist is a leading international journal focusing on high quality, original research across the broad spectrum of plant sciences, from intracellular processes through to global environmental change. The journal is owned by the New Phytologist Foundation, a not-for-profit organisation dedicated to the promotion of plant science.

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