Doctoral Dissertation Research: Investigating the Influence of Biotic and Abiotic Factors on Grasslands in the Great Plains Region of the U.S.

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NATIONAL SCIENCE FOUNDATIONGEOGRAPHY SPATIAL SCIENCES (GSS) PROGRAMABSTRACTThis doctoral dissertation research project will evaluate the influence of biotic and abiotic factors on grassland composition as exhibited through pollen assemblages. The research will provide new insights into interpretations of pollen from lake sediment cores that reveal changes in vegetation over time and contribute important information about interannual variation in pollen productivity and composition of a natural grassland environment. Although conducted in a contemporary context, the project will help answer important questions in paleoecological research by helping quantify the relationships between pollen (as a vegetation proxy) and key drivers like fire, herbivory, and topography. The project will enhance the value of a long-term dataset that is the longest-running annual record of North American grassland pollen composition. The doctoral student will work with a high school serving underrepresented populations to integrate a research-based module into their science curriculum. In addition, the project also will yield new information and insights to more effectively refine allergy assessments in the health and medical fields. As a Doctoral Dissertation Research Improvement award, this award will provide support to enable a promising student to establish a strong independent research career.North American grasslands emerged about 25 million years ago and have persisted despite dramatic changes in climate and fauna. Over time, and especially throughout the Holocene Epoch, the species composition and the extent of the biome has changed, but the role of the biotic and abiotic factors influencing those changes remain unknown. The doctoral student will conduct this project in a tallgrass prairie in Kansas. The study area is diverse, with variable topography, and includes sites that have experienced a range of different burning and grazing treatments. The research will focus on quantifying the relationships between grassland pollen assemblages and the biotic and abiotic variables influencing the region. This will be accomplished by identifying pollen from multiple traps throughout the study to produce a multi-year set of modern pollen data. The doctoral student will quantify these data in order to assess interannual variations in grassland pollen through multivariate statistical analyses. Outcomes from this research will enable better interpretation of past vegetation cover and facilitate better predictions of grassland response to human-induced shifts in fire and herbivory regimes during a range of current and possible future climatic conditions.