Plants Travel North As Temperatures Rise
In a recent report, researchers in California noted new findings of nine different plants undergoing a northward migration due to recent warming.
The wide array of plants had move to elevations 200 feet above their previous location over a period of 30 years, said researchers from the University of California, Irvine. They studied the 10 most common plant species in the Santa Rosa Mountains east of Los Angeles in 2006.
With a measuring tape, they recorded the type of plant every 400 feet from sea level to over 8,000 feet, and compared the distribution to a survey that was done in the same area in 1977.
Scientists have long warned that human-caused climate change threatens to turn plants into refugees as they migrate to higher, cooler spots to survive. The latest study is the first to physically measure changes in plants’ locations in connection with regional warming.
"The speed (of the plant movement) is alarming," said ecologist Travis Huxman of the University of Arizona in Tucson, who did not participate in the study. "It means that we’ll likely see vegetation shift a lot faster than we might think."
At least one expert offered another possible explanation that prolonged drought could be the cause of the die-off and migration.
Scientists in Irvine discovered many dead trees at lower altitudes, while plants growing uphill flourished. The habitats of nine of the 10 plant species studied crept an average 213 feet up the mountain face, the study found.
"The plant death was striking, and occurred in most species," said study co-author Michael Goulden of UC Irvine. "The occurrence of plant death was obvious to everyone living in that area."
The results appear in Monday’s issue of the journal Proceedings of the National Academy of Sciences.
U.S. Geological Survey research scientist Jon Keeley said the study provides convincing evidence of plant migration. But he said another factor, prolonged drought, rather than rising temperatures may be the driver behind the move.
"Drought certainly stands out as a real likely explanation. It is an extremely severe event" that could wipe out plants at lower elevations, he said.
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Image 1: Young oak shrubs from lower elevations fill in a higher open slope where white fir trees and Jeffrey pines have died.
Image 2: White fir trees died in the 2002 drought, while neighboring Jeffrey pines survived at this elevation.
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