Calif. Plants Put A Wrinkle In Climate Change Plans
Richard Harris
NPR
01/21/2011
As the globe warms up, many plants and animals are moving uphill to keep their cool. Conservationists are anticipating much more of this as they make plans to help natural systems adapt to a warming planet. But a new study in Science has found that plants in northern California are bucking this uphill trend in preference for wetter, lower areas.
Usually, coping with climate change is an uphill struggle for ecosystems — literally. Plants and animals want to be in a temperature zone where they can survive best.
"We see it consistently for mobile species such as insects and animals," says Solomon Dobrowski, an assistant professor of forest landscape ecology at the University of Montana. "A lot of the real foundation studies of this have come out of studies of butterflies, for example."
Dobrowski expected he'd see the same trend when he looked into historical movements of plants in a vast area of northern California. He dug through a remarkable record of the region's vegetation, collected back in the 1930s thanks to a federal project started during the Great Depression. He and his colleagues from the University of Idaho and the University of California, Davis, then compared that with modern vegetation surveys.
"What we found was counter to our expectations," he says. "We found that in fact the preponderance of plants in our study area had actually moved downhill 80 meters, or roughly 240 feet."
Water Availability Is Key
Individual plants don't move, of course, but the optimal range of many different species in the area studied has been creeping downhill. That means more new seeds sprouted downhill, and more new plants took root. This was true not just for annual plants but also for bushes and even trees.
Why would that be, Dobrowski wondered, considering that the area has warmed up. He and his colleagues say the answer lies not in the temperature, but in the amount of life-giving rain and snow. It turns out this region has been getting wetter.
"These plants are tracking water availability more so than temperature," he says.
Until now, ecologists doing this kind of study had mostly noticed a trend linked with temperature. Dobrowski says that still holds in many cases. But "the simple message — that things are going to move uphill and toward the poles — may not be the answer in all cases."
