The rush to save water is claiming legions of unintended casualties — California’s trees.

Specimens that have stood tall and strong for decades are stressed and dying because of the drought, as Californians turn off spigots to comply with Gov. Jerry Brown’s mandatory conservation measures.

All over the state — in yards, on median strips and along freeways — ghostly sheaves of brown leaves will be an enduring symbol of the drought, long after winter rains resume. Their loss will reduce habitat, shade and property values, experts say.

“It’s an emergency situation. These trees are everywhere, all around us, and are suffering,” said Rhonda Berry, president of Silicon Valley’s urban forestry nonprofit Our City Forest. She is particularly alarmed by the death of stately coastal redwoods in San Jose’s Bramhall Park and elsewhere around the South Bay.

So many trees are dying in the fourth year of this historic drought that some cities have begun delivering truckloads of water in an effort to save them. In Palo Alto, where groundwater is pumped out during basement excavations, the discarded water is collected in the city’s 2,700-gallon water truck and then used to irrigate trees.

At the state Capitol, where the lawn went brown after the governor’s executive order requiring 25 percent cutbacks in urban water use, gardeners are mulching and irrigating nearly 1,000 trees, including a historic grove planted in 1897 with saplings from famous Civil War battlefields.

“A lot of people are turning off water to lawns, which is putting mature trees in danger,” said Cindy Blain of the nonprofit California ReLeaf, which is partnering with the state’s Save Our Water conservation program to urge residents to set up alternative watering systems for trees once they turn off their regular sprinklers.

When a decision was made not to use precious city water to irrigate trees at Danville’s Eugene O’Neill National Historic Site and John Muir National Historic Site in Martinez, preservation arborist Keith Park turned to the past for solutions.

He’s using 19th century wells installed by Muir, a famed naturalist, to water the site’s 30 thirsty peach trees. At the O’Neill property, Park is relying on spring water stored in redwood tanks built by the famed writer.

“It’s less than it used to be, but it is better than nothing,” Park said.

Palo Alto is urging homeowners to add “soaker hoses” to the drip tubing around trees, then add 3 to 4 inches of mulch to retain moisture.

“We’re seeing trees starting to turn color at least a month ahead of schedule,” said city arborist Dave Dockter.

It is not just an urban problem. According to the U.S. Forest Service, the drought has already killed more than 12.5 million trees in California’s forests.

Hardest hit along the Sierra’s western slopes are pine trees, especially Jeffrey, lodge pole, ponderosa, sugar and white bark varieties. In the rocky canyons of the state’s Central Coast, the rare Santa Lucia fir shows elevated death rates.

Even centuries-old giant sequoia trees in Sequoia and Kings Canyon national parks are suffering, with more foliage dying than usual in 2014 and 2015 because of a lack of moisture, said Dana Dierkes, spokeswoman for the parks.

The current drought is already reshaping landscapes, favoring chaparral over woodland, said Patrick McIntyre of UC Davis, who manages biodiversity data for the California Department of Fish and Wildlife. His research shows that areas that have experienced the greatest water stress since the 1930s are seeing the largest decline in the density of large trees, with losses of up to 50 percent in the Sierra Nevada highlands, the Southern and Central Coast Ranges and parts of Northern California.

But, he added, the direct effect of the drought is only part of the story.

Dry trees are at greater risk of fire and predation by bark beetles and other insects, McIntyre said.

Not all trees are doing poorly.

The iconic “Lone Cypress,” perched above the ocean on a granite cliff along the 17-Mile Drive scenic roadway, is still healthy, according to the Pebble Beach Co. So is Palo Alto’s namesake, a 1,075-year-old redwood tree dubbed El Palo Alto, whose roots extend deep below San Francisquito Creek.

The world’s tallest redwoods, which have received more rain than other parts of the state in Crescent City’s Redwood National and State Parks, are also doing well.

The nearly 5,000-year-old Methuselah and its grove of gnarled bristlecone pines are accustomed to adversity, said Deb Schweizer, spokeswoman for Inyo National Forest.

When dry, the ancient trees simply drop leaves and shut down some branches to save others.

“They adapt,” Schweizer said. “They’ve been through drought stress before.”

But experts say the fragile and nonnative species that dot our urban landscapes — the ginkgos, magnolias, lindens, maples, liquidambars, European beeches and out-of-place coastal redwoods, all accustomed to routine irrigation — are suffering the most with extreme conservation.

“We need to water these trees somehow, by guess or by golly,” said Palo Alto’s Dockter. “We cannot let trees — some growing for 50 to 75 years — go south. They are an investment in our quality of life.”