As expected, the global and regional climate models gave different results, with the regional model indicating significantly smaller potential ranges in the future for the two oak species. The main reason for the difference is that the regional model shows stronger and more rapid warming at higher elevations, whereas the global model yields average results over large areas that blur the distinction between mountains and valleys within California.
The regional model yields a climate scenario in which the future range for blue oak shrinks to 59 percent of its current range, and for valley oak the future range shrinks to 54 percent of its current range. For both species, their potential habitat shifts northward, meaning that these species are not present in much of the area where climatic conditions will be right for them in the future.
"Suitable habitat is lost in the southern part of the state, and about a third of the new potential habitat is in areas where blue oaks do not currently grow. Most ecologists would not be comfortable assuming that the oaks will be able to get to those new areas," Kueppers said.
Lisa Sloan, professor of Earth sciences and a coauthor of the paper, said the shifting of ranges for oaks and other species poses a challenge for conservation planning.
"Our state parks and other protected areas are not set up to move with climate change," said Sloan, who directs UCSC's Climate Change and Impacts Laboratory where the climate model computations were carried out.
The other coauthors on the PNAS paper are postdoctoral researcher Mark Snyder; Erika Zavaleta, assistant professor of environmental
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Contact: Tim Stephens
stephens@ucsc.edu
831-459-4352
University of California - Santa Cruz
31-Oct-2005