Warming may endanger native plant, 'U' finds
Copyright 2001
Star Tribune (Minneapolis, MN)
October 5, 2001
By Tom Meersman; Staff Writer
The research, published today in the journal Science, focuses on the partridge pea, a yellow-flowered plant, but the findings raise the possibility that other native plants would be in jeopardy if the climate warms over the next 25 to 35 years, as some computer models predict.
Ecologists see the survival of native plants as critical to natural diversity because different plants sometimes need one another for survival and support large populations of insects, bees, birds and other wildlife.
According to a climate model used for the study, Minnesota by 2035 is predicted to be a lot like present-day Kansas: about 7 degrees warmer, on average, during the summer. Julie Etterson, who attended the University of Minnesota and is now a postdoctoral biology research associate at the University of Virginia, planted seeds from Minnesota partridge peas in Kansas and Oklahoma, where the average summer temperature is even higher than Kansas'.
She found that the Minnesota plants did poorly; they had 84 percent fewer seeds in Kansas and 94 percent fewer seeds in Oklahoma. So Etterson studied how long it would take for the Minnesota partridge pea to adapt to a climate change on its own.
Among other things, she and another researcher estimated it would take 79 years for the partridge pea to develop leaves thick enough to withstand the higher temperatures and lower soil moisture of a Kansaslike climate.
"Our findings suggest that we should not assume that plant populations will evolve fast enough to keep pace with climate change," Etterson said.
Ruth Shaw, a University of Minnesota professor who specializes in evolutionary genetics and is co-author of the research paper, said that in previous periods of climate change, plants spread naturally across the landscape over many years and migrated to a different latitude.
"One might think that plants could just do that again," Shaw said. "But the landscape is very different with urbanization and agriculture, and there are not great continuous areas through which native plants can progressively colonize."
Alarming results
Bob Djupstrom, a supervisor in the Minnesota Department of Natural Resources (DNR) ecological services division, called the study results alarming but consistent with other research about global warming's potential to affect forest growth and wildlife habitat.
"This causes concern for all of our native community species and the viability of our nature reserve system, not only in Minnesota, but across the country," Djupstrom said. "We might have to look at transplanting species northward to allow survival in the wild of those same genetic populations."
But Djupstrom, who manages 135 areas across the state designated for biological diversity and scientific research, said relocating plants raises other ecological concerns. Different areas have different soil types, microbes and fungi, which could significantly reduce the success rate of transplanting projects, he said. And although individual species might survive, he said, communities of plants such as those found in native prairies might be difficult to reestablish.
Many scientists think emissions of carbon dioxide and other gases are causing global warming; much research has been done on the subject. Etterson and Shaw stressed that their research pertains only to the partridge pea, an annual legume, and that other native plants such as perennials and grasses also should be studied.
Joel Kingsolver, a University of North Carolina biology professor and editor of a book on the biological effects of global climate change, said the Minnesota research is an important first step in showing that the genetics of some plants is constrained.
"This is one prairie plant and you can't generalize these findings to everything," Kingsolver said. "On the other hand, there's no reason to think that the partridge pea is atypical or weird or unusual in some way" and that similar findings may not be proven for other Minnesota species.
Insects go through five or more generations a year and have enormous populations, he said, so they probably can adapt to a warmer climate. But many birds or mammals with smaller populations and longer generations will have a more difficult time, he said.
"There's a whole huge area in between. How plants will respond to global warming, that's an open question," he said. "It's a very important research area."