Alicia Chang, Associated Press Yahoo News 11 Aug 08;
Striking new research in the Southern California mountains suggests recent warming is behind a massive die-off and rapid migration to higher ground by nine different plants — from desert shrubs to white firs.
Within 30 years, most had moved to elevations 200 feet above their previous growth range. The findings provide a glimpse of what could happen to the world's vegetation as the Earth faces inevitable global warming.
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 — whether man-made or part of a normal cycle — over the past three decades.
"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."
However, at least one expert suggested that prolonged drought — not climate change — could be the cause of the die-off and migration.
Researchers from the University of California, Irvine in 2006 studied the 10 most common plant species in the Santa Rosa Mountains east of Los Angeles at different elevations. 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.
The Santa Rosa Mountains host diverse habitats, including conifer forest, chaparral, woodland and desert scrub. Since the 1970s, the region has seen average temperatures rise 2 degrees as well as extended periods of drought.
To scientists' surprise, they found scores of dead trees and shrubs at lower altitudes, but flourishing plants uphill. 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.
The findings counter the idea that fast-growing grasses are more flighty than large woody trees since the various plant species edged a similar distance upward in the study, scientists say.
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.
Goulden of UC Irvine concurred that the 1999-02 severe drought can be partly blamed for killing plants, but he said drought alone cannot explain the uphill movement.
The researchers ruled out air pollution as a potential cause since they could not find signs of ozone damage to the plants. They also ruled out wildfire since the last major blaze to sweep through occurred more than a half century ago.
Though the researchers could not determine if the hotter temperatures in the region were due to greenhouse gas emissions or part of a natural warming cycle, they say the widespread plant death and migration observed is similar to global warming predictions.
Plants and Animals Move as Climate Warms
Andrea Thompson, LiveScience.com Yahoo News 12 Aug 08;
Climate change has shifted the boundaries of plant and animal habitats, with some birds in the United States extending their boundaries northward and trees moving farther up mountains, new studies show.
Between 2000 and 2005, New York state's Department of Environmental Conservation had thousands of volunteers all over the state observe and report the birds they could identify, creating a Breeding Bird Atlas of the various species' breeding ranges.
Researchers at the State University of New York (SUNY) compared this atlas to another one conducted between 1980 and 1985 for 83 species of birds that traditionally have bred in New York and found that many had extended their range boundaries northward, some by as many as 40 miles (64 kilometers).
"But the real signal came out with some of the northerly species that are more common in Canada and the northern part of the U.S.," said Benjamin Zuckerberg, a Ph.D. student at SUNY. "Their southern range boundaries are actually moving northward as well, at a much faster clip."
Some of the species making this southern boundary shift are the Nashville warbler, a little bird with a yellow belly; the pine siskin, a common finch that resembles a sparrow; and the red-bellied woodpecker, considered the most common woodpecker in the Southeast.
The shifts, announced today, are occurring in a relatively short amount of time, the researchers also pointed out, happening in a matter of decades. These changes are also consistent with the predictions of regional warming, they added.
Warming is also forcing some mountain plant species to adapt by moving to higher altitudes as it kills them in their traditional ranges. In Southern California, for example, warming temperatures and longer dry spells have killed thousands of tree and plants, while pushing their habitats an average of 213 feet up the Santa Rosa Mountains over the past 30 years, according to a new study detailed in the Aug. 11 issue of the journal Proceedings of the National Academy of Sciences.
Previous studies have also catalogued the ways that climate change is knocking the nature out of whack: birds are migrating earlier in the season; reptiles and amphibians are also heading for the hills to reach cooler climes; and the timing of plant blooms is shifting as the Earth heats up.
