Chicago Botanic Garden Fall 2020

18 chicagobotanic.org Fire may be this prairie flower’s best friend When you think of fires that occur in the natural world, you might think of destruction and loss of wildlife. But when it comes to the North American prairie, fires are crucial for native plants to thrive. Managers light fires to safeguard plants against extinction. Until now, it was unclear precisely why and how fires could promote the popu- lation health of plants and maintain plant diversity in fire-dependent eco- systems. A 21-year study by Stuart Wa- genius, Ph.D., and a team of conserva- tion scientists at the Chicago Botanic Garden’s Negaunee Institute for Plant Conservation Science and Action found that burning the prairies helps plants synchronize the bloom time of Echinacea angustifolia , commonly known as the narrow-leaved purple coneflower, making it easier for the plants to mate and reproduce. “We found evidence that two things— being closer to potential mates, and flowering at the same time as potential mates—really increase the number of seeds that they produce,” said Dr. Wagenius. The study was published in the Proceed- ings of the National Academy of Sciences or PNAS, one of the world’s most-cited and comprehensive scientific journals. “I hope this paper will serve as a boost to all those people who are managing prairies. They know that fires are good because they set back weeds, kill shrubs, and help the native plants, but now they’ll have another reason—they’re helping plants flower and produce seeds for the next generation.” Wagenius got an inkling of the impact of fires on native prairie plants based on research of smaller prairie patches that haven’t burned. “We found that there’s reproductive failure of many of the flowering plants, even though they look fine. It turns out that those plants were isolated,” said Wagenius. “We also noticed that there were many coneflower plants on a big preserve, but they flowered mostly in the year right after a prescribed burn,” he said. “So, in most years, those plants are isolated, but the fire brings plants together.” These observations led Wagenius and his team of conservation scientists and volunteers to conduct an extensive ex- periment to figure out if the fire affect- ed pollination, or reproductive success. Through the Echinacea Project, they studied the coneflower on a 100-acre prairie preserve in western Minnesota.