NPR’s “Morning Edition” program recently featured a study of Northern California plants by University of Montana assistant professor of forest landscape ecology Solomon Dobrowski and colleagues at UM, the University of Idaho and the University of California, Davis.
The gist of the study, which was published in the Jan. 21 issue of the journal Science, is that as the climate warmed in the 20th century, plant and animal species usually moved uphill seeking cooler temperatures. But that wasn’t the case for 64 plant species in Northern California. Instead, the plants shifted downhill, following available water.
According to the NPR report, Dobrowski and his colleagues compared data collected in the 1930 as part of a federal project to modern plant surveys.
“What we found was counter to our expectations,” Dobrowski told NPR science correspondent Richard Harris. “We found that in fact the preponderance of plants in our study area had actually moved downhill 80 meters, or roughly 240 feet.”
From Harris’ report:
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.”
Shifts within an ecosystem could be awkward, the NPR report notes, if a plant moves downhill and an animal that depends on it moves uphill.
“You could have situations in which plant and animal communities are even disrupted further,” Dobrowski told Harris.