Evan Gora still remembers the first time he climbed a tree that had been struck by lightning. The trunk of this strangler fig was as wide as a car. Its leaves were waxy and boat-shaped. At first glance, the tree didn’t look like it had been toasted by 300 million volts of electricity.
But as Gora hefted his way up, he saw faint signs that it had been zapped 10 days before. Leaves at the tips of some branches were scorched and dead. Lightning had jumped from these branches to neighboring trees, Gora realized.
He also saw that the lightning had traveled from tree to tree across ropy growths known as lianas. They’re thick, woody vines. A single liana often extends across multiple trees, wiring them together. And if lightning strikes one, it can now be bad news for the others.
“Lianas are carrying [electric] current, like jumper cables, across the canopy,” says Gora. He’s a forest ecologist at the Cary Institute of Ecosystem Studies in Millbrook, N.Y. By connecting these trees, the vines “might amplify the effects of lightning.”
Gora encountered these zapped trees on Barro Colorado Island in Panama, a country in Central America. The trees grew on a densely forested hill in a lake. Here, the whoops of howler monkeys often ring through the air.
Lianas’ ability to spread lightning between trees is just one way they’re changing the tropics.
For 40 years, lianas’ numbers have been rising in tropical forests across South and Central America. Their spread may be related to severe dry seasons caused by climate change. But one thing is clear: These woody serpents are ripping forests apart.
Lianas smother trees in shade, stealing sunlight that could have fueled forest growth. They also topple trees. And as Gora has now found, they may cause more trees to die when lightning strikes.
All of this could have dire consequences for the future of Earth’s climate.
Carbon dioxide (CO2) levels in the atmosphere are…
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