The drought that punished California from 2010 to 2015 killed more than 100 million trees, but some in Northern California’s Mendocino County survived just fine. How did they do it? Researchers from the University of Texas at Austin and the University of California, Berkeley, have found that—just like humans fracking oil and gas deposits in shale—tree roots are able to access substantial quantities of water stored in weathered bedrock.
However it’s held, the amount of water is significant—4 to 21 inches of rock moisture was found in the test wells. Importantly, the amount of moisture held by the rock remains stable year over year, topping up whether winter rains are plentiful or scanty, with the remainder draining off into the groundwater table.