Plants are spreading up mountains faster than thought in North America

From Mexico to Canada, mountain plants are migrating uphill to cooler elevations. In some mountain ranges, the rate of ascent is as high as 112 meters per decade.

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In the face of climate change, mountain plants in western North America are expanding to higher, cooler elevations faster than previously thought. Is not …

As global temperatures rise due to climate change, plants and animals that have evolved to live in specific environmental conditions are being forced to adapt quickly to the new normal. One way seeds survive the heat is by moving to higher ground. Ecologists already knew that species respond to environmental changes, says James Kellner of Brown University in Rhode Island. “The question is, to what extent? And can they catch up?

To learn more about the rate of vegetation change, Kellner and his colleagues compared NASA Landsat satellite imagery of nine mountain ranges in western North America between 1984 and 2011.

“We’re talking about a very large area of ​​the world here, from southern Mexico to the Canadian Rockies,” Kellner says.

When researchers looked at peak “greenness” (a measure of vegetation cover at the height of the growing season) on mountain slopes, they found rapid changes. Plants he was moving an average of 67 meters higher every decade, more than four times as fast. than previously reported. In New Mexico, where vegetation was moving fastest, he rose more than 112 meters per decade.

Warming is not the only reason vegetation moves up slopes. Changes in precipitation patterns, or ecological disruptions such as agriculture, livestock grazing, and fires, could also be responsible for the shift to the sky. But Kellner said finding the pattern in different mountain ranges suggests one common factor: rising temperatures.

“It’s pretty hard to think of any explanation for this. [pattern] It’s unlike anything that’s consistently operated in nine mountain ranges between Mexico and Canada,” says Kellner. Climate change is also affecting precipitation amounts and timing in some areas, but patterns are not stable across all regions.

The rapid rise of some plants may still not be fast enough. When the team compared the rates of uphill change measured in his five mountain ranges in the United States to those predicted by recent warming, only plants in his two mountain ranges in New Mexico and the Sierra Nevada responded to climate change.

“If species are pushed outside the range where they can have viable and sustainable populations, we could be in a situation where we lose them,” Kellner says.

The nearly 30-year time period and geographic extent analyzed are the main strengths of the study, says Sabine Rumpf of the University of Basel, Switzerland. But because the study looked at vegetation as a whole, Basel says, the findings don’t tell us what’s happening to individual plant species.

“The problem is that species variation is very different [from one another] – There is a big difference. ’” She says the findings are “a wake-up call that the species is already on the move.”