Reproductive Failure In Joshua Trees In CA; Drier, Hotter Mojave Killing Young Trees

JOSHUA TREE NATIONAL PARK – It's one of the most picturesque desert landscapes on the planet: the crooked, prickly branches of Joshua trees jutting skyward in fantastic shapes against backdrops of granite boulders. But in parts of Joshua Tree National Park, these iconic trees are gradually dying out.

The knee-high young trees that normally would sprout here have largely vanished from some areas of the national park as the climate has grown hotter and drier in recent decades. The remaining mature trees are slowly dying, their gnarled branches collapsing to the ground. In portions of the park, the Joshua trees that still stand could be the last generation. "Around the edges is where we're starting to see thinning like this," said Josh Hoines, the national park's vegetation branch chief, scanning a patch of desert dotted with fully grown trees. "We hardly see anything that resembles a small tree."

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Prolonged drought and a hotter climate are taking a toll on a wide range of plants in the deserts of the Southwest. California junipers have been dying in some areas, leaving pale gray skeletons of branches. Pinyon pines are also dying rapidly, attacked by beetles that have flourished due to milder winters. Researchers have confirmed that many species of trees and shrubs are gradually moving uphill in the Santa Rosa Mountains, and in Death Valley, photographs taken decades apart have captured a stunning shift as the endangered dune grass has been vanishing, leaving bare wind-rippled sand dunes.

These changes in desert plants offer glimpses of profound transformations that hotter global temperatures are likely to bring for wildlife, water supplies, and people in a region that is already the hottest and driest in the nation. A Desert Sun analysis of national climate data from more than 30 weather stations across the Southwest, in places from Palm Springs to Tucson, found that average monthly temperatures were 1.7 degrees Fahrenheit hotter during the past 20 years as compared to the average before 1960 – a time frame often used by scientists in studying climate change.

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http://www.desertsun.com/longform/news/environment/2014/05/31/global-warming-joshua-tree-national-park/9729285/