RAPID: Cicadas as catalysts: Quantifying the population, community, and evolutionary effects of a periodic resource pulse.

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The Brood X cicada emergence is a unique event as billions of cicadas emerge after accumulating resources belowground for seventeen years and transfer those resources to the soil surface. This rapid transfer of resources from belowground to aboveground acts like plant fertilizer and increases soil nitrogen availability. Because nitrogen is frequently the nutrient plants need most, this fertilization will likely affect plant community composition (which species are present and most abundant), promote invasive species, and alter plant interactions with insect herbivores and both beneficial and harmful microorganisms. The abundance of resources caused by decaying cicada carcasses also may affect plant demography (whether the plant population expands or declines) and how plants and microbes evolve. Even though the resource pulse is short-lived, many of these effects may affect forest understories in the region for years to come. The goal of this project is to study the effect of cicada emergence on plant communities and plant-microbial-insect interactions. The project also capitalizes on the charismatic cicada emergence to generate excitement about science in K-12 classrooms. The researchers will collaborate with a K-12 teacher who will work alongside undergraduate students, graduate students, and the PI to develop hands-on classroom STEM activities.The influence of rare events on ecology and evolution is challenging to study because of their largely unpredictable nature. In this case, this project capitalizes on the cicada emergence to install experiments that quantify both the immediate and long-term effects of periodical resource pulses. The project involves adding and removing thousands of cicada carcasses from plots in the forest. This experiment will be used to answer questions in the fields of evolutionary ecology, community ecology, and population ecology. First, the researchers will measure natural selection on plant traits to investigate how nitrogen affects plant evolution and will isolate nitrogen-fixing rhizobia to test theoretical predictions that increased resources cause the evolution of less cooperative rhizobia. Second, the researchers will test how cicada carcass treatments affect plant-herbivore and plant-microbe interactions, plant community composition, and whether the resulting resource pulse creates "invasion windows" that promote invasive species. Finally, the researchers will conduct demographic studies on focal species to test how the resource pulse contributes to population increases (or declines). In sum, this project investigates how a rare event alters forest understory ecology and evolution immediately, but also sets the stage for investigating long-term effects.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.