Some flowers thrive after fire, study says
Watching fires rage across Australia, destroying ecosystems and killing millions of animals, it was hard to imagine any good emerging from such devastation. But it has long been known that some small plants can benefit from a fire because they grow back faster than grasses and trees, giving them an advantage in the battle for resources.
A study published Jan. 27 in the Proceedings of the National Academy of Sciences gives another explanation for that success, at least for one prairie plant that has been in decline: reproductive advantage.
Purple coneflowers, also known as echinacea angustifolia, produce more seeds in years after fires, the new study found, not just because there are fewer competitors for resources, but because a fire “also changes the mating opportunities,” said Stuart Wagenius, a conservation scientist at the Chicago Botanic Garden. Wagenius, who led the research, tracked a 40-hectare plot, or nearly 100 acres, of prairie land in Minnesota for 21 years as part of the Echinacea Project.
The study found that coneflowers produced more seeds and were more genetically diverse in plots that were burned every few years.
Coneflowers don’t bloom every year because it takes energy to produce a flower. Controlled burning in fall or spring triggered the flowers to put out blooms — often more than one — the following summer. Wagenius found this synchrony in terms of the years of flowering and the dates within those years. So, in the summer after a fire, more flowers were open at the same time, and bees were better able to pollinate the coneflowers, he said.
“It just makes sense that if there are more plants flowering, there’s going to be better pollination,” he said.
Several other researchers not involved in the work said the group’s findings were surprising and persuasive.
“They show that the effect of fire isn’t what everybody assumed that it is,” said Ingrid Parker, chair of the department of ecology and evolutionary biology at the University of California, Santa Cruz.