Improving Reconstructions of Open Vegetation in North America: Pollen-Productivity Estimates for Grassland Plants

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The Great Plains of the U.S. experience remarkable climate variability that is projected to increase in the next two decades. Knowledge of grassland response to past and future climate changes is relatively primitive, however. The purpose of this research project is to develop a method to reconstruct quantitative grassland cover from pollen records preserved in sediment. The project will employ a coupled empirical and theoretical approach to lay the foundation for quantitative reconstructions of grassland vegetation in North America. It will be conducted in the Flint Hills of Kansas, the largest contiguous expanse of native tallgrass prairie in the U.S. The project has three main goals. The first goal is to determine pollen productivity for 13 common plant types in the grassland. This will be accomplished by obtaining pollen preserved in sediment from many small ponds in the Flint Hills and conducting detailed vegetation surveys around each pond where pollen is collected. A computer model will calibrate the relationships between pollen and vegetation, which will produce an estimate of pollen productivity for each type of grassland plant. The second goal is to establish both the regional and local spatial scales of grassland vegetation represented by pollen in sedimentary basins. This is a key step to providing spatially explicit estimates of the cover of grassland plants over time as climate changes. The final goal of the project is to reconstruct regional grassland vegetation for the past several decades by using the newly-derived pollen productivity estimates. The investigators will obtain a sediment core from a large lake in the Flint Hills. Pollen assemblages from the past 50 years will be quantified from the sediments, as will land cover surrounding the basin from aerial photos and remote sensing data. Overall, this research will improve interpretations of how grassland vegetation and climate have interacted in the past and how they are likely to interact in the future. This knowledge is becoming more important as human pressure on the grassland biome increases.Much of the economy of the Great Plains of the U.S. depends on grassland resilience to climate variability. The results of this project will help discern how grassland composition and productivity have responded to past climate changes. It also will produce information about two trends perceived as undesirable by residents of the region, the causes of woody plant expansion and the factors correlated with allergenic pollen in the atmosphere. A significant portion of the research project will train undergraduate and graduate students to conduct field and laboratory activities. Using infrastructure developed by Kansas State University's Women in Engineering and Science Program, researchers will take part in outreach to K-12 girls interested in science. Data generated by the project will be shared with the North American Pollen Database for use by other researchers.