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Rainforest biodiversity at risk from global warming
mongabay.com
October 9, 2008


Climbing temperatures may doom many tropical species to extinction if they are unable to migrate to higher elevations or cooler latitudes, report researchers writing in Science.

Analyzing data for 1,902 species of plants, insects, and fungi in the tropics, Robert Colwell and colleagues warn that lowland areas are particularly at risk of biodiversity loss due to warming since "there is no source of species adapted to higher temperatures to replace those driven upslope by warming," according to Science. The authors estimate that more than half the species they studied in Costa Rica could potentially face such risks. At the same time species adapted to high elevations will be faced with "mountaintop extinctions" when they reach the summit of mountains.

A second study, by Craig Moritz and colleagues, found that warming in California's Yosemite National Park has already caused elevational shifts in the range of mammals species.

"These kinds of changes in community composition have been going on forever," said James Patton, a UC Berkeley professor emeritus of integrative biology who led the field work for the second study in Yosemite. "The only thing that makes this different is that it has probably happened in our lifetime. It is the speed with which these changes are taking place that gives one pause."

Gunnar Brehm, a co-author of the study in Costa Rica, collecting moths at a blacklight lure at 500 m of elevation in Costa Rica. Image courtesy of Brehm

"If change happens too fast, elements of the system may start to collapse because a keystone element of that system gets pulled out too quickly," he continued. "That is something we just don't know. From my standpoint, if I had the opportunity, I would want to minimize the rate of change."

Moritz added that because Yosemite is well protected, its species will fare better than those in non-protected areas.

"Yosemite has been very well managed so that species have been allowed to move," said Moritz, a UC Berkeley professor of integrative biology and director of the campus's Museum of Vertebrate Zoology. "We need to continue to protect large swatches of public land from land-use changes."

The results of both studies suggest that global warming will present challenges not seen in tens of millions of years for the world's biodiversity.

Robert Colwell, et al. Global Warming, Elevational Range Shifts, and Lowland Biotic Attrition in the Wet Tropics. SCIENCE 10 OCTOBER 2008 VOL 322

Craig Moritz, et al. Impact of a Century of Climate Change on Small Mammal Communities in Yosemite National Park. SCIENCE 10 OCTOBER 2008 VOL 322