SG: Demographic drivers of plant community response to fire: Re-evaluating the relative importance of survival vs. reproduction

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Before European-American settlement in the 1800s, the vast grasslands of North America burned every 2-5 years. These frequent fires maintained grassland habitat and contributed to the diversity of birds, mammals, insects, and plants found in prairies today. Widespread habitat loss and the elimination of fire are causing native plant populations to decline in the few prairie patches that remain. The loss of native plant diversity has motivated many Americans to take action. People, businesses, and agencies of local, state, and the federal government conduct prescribed burns to improve habitat and promote prairie plant diversity. Understanding why native prairie plants thrive with fire is essential for achieving these management goals. In addition to sharing results that will advance the fundamental scientific knowledge about fires and plant populations, the researchers will share practical information with land managers, conservation practitioners, policy-makers, and the public to help them make better decisions about how frequently to burn prairies to achieve their management goals. In addition to disseminating scientific results and recommendations, this project will provide research experience and training to a postdoctoral researcher and two college students, as well as opportunities for engagement by high-school students, secondary-school science teachers, and conservation research volunteers in Minnesota and at the Chicago Botanic Garden.This research project will investigate how fire maintains healthy populations of native perennial plants in western Minnesota. Scientists have two main hypotheses about fire: on one hand, fires may help native plants compete and survive; on the other hand, fires may help plants flower, get pollinated, and produce seeds. Evidence exists for both hypotheses and both survival and reproduction are necessary to maintain a population, but how much fire influences each process remains an open scientific question. The researchers will test the hypothesis that the reproductive benefits of synchronized flowering after fire help promote population growth and forestall local extinctions. They will randomly assign burn treatments in 30 prairies, where they will 1) examine the effects of fire on pollination and reproduction in previously-studied populations of a purple coneflower, Echinacea angustifolia, 2) conduct a seed addition experiment to characterize the influence of fire on seed germination and seedling survival, 3) develop models to quantify effects of fire on Echinacea population growth, and 4) estimate fire effects on mating and reproduction in three other widespread prairie species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.