Calif. Plants Squeezed by Climate Change

June 25, 2008 -- The ranges of up to two-thirds of the 2,387 plant species found only in California may shrink by more than 80 percent under predicted climate change.

An 80 percent reduction in habitat in 100 years is the threshold for classification as "critically endangered" by the International Union for the Conservation of Nature, which maintains the well-known Red List of Threatened Species.

"This is the first time that anyone has made the attempt to look at so many species, and I think it's kind of a wake-up call that we can expect some pretty dramatic changes," said plant ecologist Philip Rundel of the University of California, Los Angeles, who was not a part of the study.

"It's very clear that we're going to lose a lot of species to global warming, and when you get to species that are narrowly restricted like so many in California, the problem is worse," added Peter Raven, President of the Missouri Botanical Garden in St. Louis.

To make the predictions, a team led by David Ackerly at the University of California, Berkeley, combined regional models for predicting climate change with known information about the current range of California plants to predict what regions would have a matching climate in the future.

In general, plants will retreat northward or to higher elevations as climate warms, the researchers reported online in the journal PLoS ONE.

"We found several places we're calling 'climate change refugia,'" said the study's first author, Scott Loarie of Duke University in Durham, N.C.

"These are places where a large diversity of these species might persist. What's important about these refugia is that they include the plants that are really going to be threatened," he added. "It's important that these areas are set aside, but also whether these plants can get to them."