It seems like a sin of nature that trees may be adding to the misery of California's extreme drought.
But that may be the case, according to researchers from the University of California. The problem is with forests that have grown denser with trees and brush over time in California's Sierra Nevada mountains.
What's good for the trees may be bad for people. That's because the trees are soaking up a lot more water that would normally be filling up many of the state's reservoirs, which are at very low levels because of three years of severe drought
"More trees means more water stays in the forest," said Roger Bales, a hydrologist at the University of California at Merced, who was co-author of the report on increased mountain vegetation from the effects of climate change.
"It's the same idea like planting more plants in your garden," he said. "The more plants you have, the more water you need for them."
Bales said that around 60 percent of California's consumable water comes from the Sierra Nevada region.
But the increased high-altitude vegetation there could decrease freshwater runoff by up to 25 percent in the decades to come, according to Bales' study.
"This doesn't help the drought," said Michael Goulden, a professor of earth system science at the University of California at Irvine, and a study co-author.
"But the alarm bells on the research we've done are really for the future," he said. "It's a wake-up call for scientists to do a lot more study on the issue."