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

国家科学基础地理空间科学(GSS)进展这项博士论文研究项目将通过花粉组合来评估生物和非生物因素对草地组成的影响。这项研究将为解释湖泊沉积岩心中的花粉提供新的见解，揭示植被随时间的变化，并为花粉生产力的年际变化和天然草原环境的组成提供重要信息。尽管该项目是在当代背景下进行的，但通过帮助量化花粉(作为植被替代品)与火、草食和地形等关键驱动因素之间的关系，该项目将有助于回答古生态研究中的重要问题。该项目将提高长期数据集的价值，该数据集是北美草原花粉组成的最长年度记录。博士生将与一所服务于代表性不足人群的高中合作，将一个以研究为基础的模块整合到他们的科学课程中。此外，该项目还将产生新的信息和见解，以更有效地完善卫生和医疗领域的过敏评估。作为博士论文研究改进奖，该奖项将提供支持，使有前途的学生能够建立强大的独立研究生涯。北美草原大约出现在2500万年前，尽管气候和动物发生了戏剧性的变化，但它仍然存在。随着时间的推移，特别是在整个全新世时期，生物群的物种组成和范围发生了变化，但影响这些变化的生物和非生物因素的作用仍然未知。这位博士生将在堪萨斯州的一片高草草原上进行这个项目。研究区域多样，地形多变，包括经历过一系列不同焚烧和放牧处理的地点。这项研究将侧重于量化草原花粉组合与影响该地区的生物和非生物变量之间的关系。这将通过在整个研究过程中识别来自多个圈闭的花粉来实现，以产生一组多年的现代花粉数据。博士生将对这些数据进行量化，以便通过多元统计分析来评估草原花粉的年际变化。这项研究的结果将有助于更好地解释过去的植被覆盖，并有助于更好地预测草原在当前和可能的未来气候条件下对人类引起的火和草食制度变化的反应。

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.