Cloud Forest Trees Use Leaves To Consume Water

Scientists at the University of California, Berkeley, have discovered that tropical montane cloud forest trees just don't rely on their roots to take up water but they also depend on their leaves to consume water from the clouds directly.

The scientists claim this to be an essential strategy the trees adopt in order to survive in the otherwise dry areas. But the study notes that the clouds these trees depend on are fast disappearing due to the drastic climate change.

According to Todd Dawson, senior author of the study and UC Berkeley professor of integrative biology, "The study highlights the vulnerability of this rare and already endangered ecosystem to climate change."

Prior to this, the alteration in the cloud blanket has been linked to the sudden drop and disappearance of the cloud forest animal population.

Greg Goldsmith, the lead author of the study and a graduate student in the Dawson's lab explains the functioning of these tropical montane cloud forests. He says that these leaves are constantly soaked in the clouds.  The cloud forest trees leaves consume the cloud water when there isn't sufficient water supplied from the soil.

"Many cloud forests experience an annual dry season when the primary water source isn't rain, but rather, the moisture from the clouds," he said. "This is when the trees are most likely to draw water in through their leaves."

While working in Monteverde, Costa Rica, the reasearchers carefully analyzed the patterns of wetness that were formed on the soaked leaves. They did this by setting up small plastic leaves that use changes in the voltage of an embedded electrical circuit to detect wetness.

In order to check whether or not water was entering leaves when they were wet, the team went on to setting miniature sensors on the branches of cloud forest plants.

"The textbooks teach us that water enters roots, moves up the trunk and into the branches, then finally exits the leaves. That's true, but it's not the whole story," Goldsmith said. "With our sensors, we observed water entering the leaves and actually moving back down the branches toward the trunk."

The study found that all trees can consume same amount of water.

"The trees that are drinking the most water through their leaves may be more vulnerable to decreases in cloud cover resulting from rising temperatures," said Goldsmith, who received funding from the National Geographic Society Young Explorers Grant to conduct the research.

"The study provides a clear demonstration of the interactions between clouds and cloud forest plants and will serve as a cornerstone for future research on the effects of climate change on tropical montane cloud forest ecosystems," Dawson added.

The new study will be published next year in the journal Ecology Letters.