Will Plants Move Fast Enough to Keep Up With Contemporary Climate Change
Researchers James Clark and Gabriel Katul Take Different Approaches to Speculate on the Future
By Monte Basgall
As the climate began warming and glaciers from Earth’s last ice age began melting, evidence suggests that North American temperate zone plants huddling in the relative warmth further south began a northward migration to gain ground lost during the big chill. With plants now poised to begin another mass movement in response to human-induced global warming, will the past repeat itself?
Nicholas School researchers James Clark and Gabriel Katul, who have both studied in different ways how seeds and pollen spread to new territory, were asked to do what trained scientists hate: speculate. Will plants be able to move fast enough to keep up with the contemporary climate changes that already appear to be causing Alaskan permafrost to melt? And how will trees and other plant life adapt to other alterations suggested by the latest computer predictions, including intensification of extreme events such as longer droughts, heavier rainfall and amplification of both minimum and maximum air temperature.
Clark, the H.L. Blomquist Professor of Biology, is an ecologist at both the Nicholas School and the biology department who studies how global change affects forests and grasslands. Looking back in time, he has enlisted genetic information as well as ancient sediments to make some surprising deductions about plant responses to ancient climates. He and his research group also use seed traps and mathematical modeling to meticulously trace how contemporary seeds are spread about by the wind.
Assessments that he and associates have made of post-Ice Age plant responses are “incredibly important, because they are our only previous experience with rapid global warming,” he says. “At the end of the Ice Age things warmed up pretty quick.” Then growing cautious, he adds: “But it’s not as rapid as we’re seeing today. The danger is to try and take our understanding of that experience and drop it down in 2050.”
Katul, a Nicholas School professor of hydrology and micrometeorology mechanics, studies seed and pollen propagation as an extension of his physics and mathematics oriented interest in mass, momentum, and energy exchange between the land surface and the atmosphere.
He doesn’t claim Clark’s biological expertise to predict how plants might react to changing climatic conditions. But, by collecting wind-borne seeds on a tower near the Duke campus in collaboration with life scientists, Katul has helped develop some unique mathematical models that seem to emulate actual observations of how high and how far seeds can be boosted by winds at various heights in forest canopies and, by extension, how fast and distant they could spread.
He and collaborators envision a future in which the movement of seeds and other biological material could be reliably computer-simulated from very short time and distance scales to very long ones over many years. “The question is can we really unfold all this complexity in a computer?” he asks. “With time, I think the answer will be yes.”
photo captions:1. Jim Clark with a collecting basket at the Duke Forest FACE site. 2. Research tower in Duke Forest. 3. Gaby Katul