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January 22, 2018 – Sierra Nevada trees have noticed it’s getting warmer, and they are voting with their feet.

Seedlings of three species of cold-loving conifers are no longer sprouting and growing in middle elevations where they used to be common, state biologists with the California Department of Fish and Wildlife found.

Mountain hemlock trees (Tsuga mertensiana) in the high elevations of Desolation Wilderness, near Lake Tahoe, Calif. Wikimedia Commons photo

They counted young trees at different elevations in the Sierra Nevada and compared their findings to detailed surveys taken 80 years earlier. Of 12 tree species studied, three of them – red fir, western white pine and mountain hemlock – already live in the highest ranges of the Sierra Nevada.

But their lower-elevation boundaries have moved uphill.

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The mountain hemlock, a towering conifer that likes the coolest climes, made the biggest shift. Seedlings now sprout 700 feet higher – the length of more than two football fields – than they did 80 years ago, the study found. (Nevada County’s higher elevations offer an important refuge to this tree, researchers added.)

Higher-elevation boundaries, however, have not risen. That means high-altitude trees have less surface area to populate, leading to greater species competition, researchers wrote.

Trina Kleist is a Grass Valley freelance writer whose clients include Nevada Irrigation District. She may be contacted at tkleistwrites@gmail.com or (530) 575-6132.