By Daniel Grossman AMAZONAS, Brazil: Two researchers wearing long-sleeved shirts and pants to resist mosquitos, and high boots to block snake bites, gaze at a shattered tree. It lies on the ground garlanded in palm fronds, stretching far into the forest. Until recently, it had towered over most other trees in this vast rainforest. “It’s lightning, obviously,” says Evan Gora, declaring the tree’s cause of death. He’s a staff scientist at the Cary Institute of Ecosystem Studies in Millbrook, New York. “You can see burned leaves on the top,” agrees Adriane Esquivel Muelbert. She’s a professor at …