Thirsty Wood's Distress Call Heard in Lab

Like a person gasping for air when it's in short supply, living trees make noises when they are running out of water. Air bubbles form when a tree is trying to suck moisture out of dry ground during droughts. As leaves on a tree collect carbon dioxide, they open their pores, a process that leaves them vulnerable to water loss. Evaporation from the leaves pulls water up the trees in a state of tension. Douglas firs and pine trees can repair this damage as frequently as every hour, said Katherine McCulloh, a plant ecophysiologist at Oregon State University, Department of Forest Ecosystems and Society.