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

美国大平原经历了显着的气候变化，预计未来20年这种变化将会加剧。然而，关于草原对过去和未来气候变化的反应的知识相对原始。这项研究的目的是开发一种方法，从保存在沉积物中的花粉记录中重建定量的草原覆盖。该项目将采用经验和理论相结合的方法，为北美草原植被的定量重建奠定基础。它将在堪萨斯州的弗林特山进行，这是美国最大的连续的原生高草草原。该项目有三个主要目标。第一个目标是测定草原上13种常见植物的花粉生产力。这将通过从弗林特山的许多小池塘中获取保存在沉积物中的花粉，并在收集花粉的每个池塘周围进行详细的植被调查来实现。计算机模型将校准花粉和植被之间的关系，这将产生每种草原植物的花粉生产力估计。第二个目标是建立沉积盆地中以花粉为代表的草原植被的区域和局部空间尺度。这是提供随气候变化随时间变化的草原植物覆盖率的空间显式估计的关键一步。该项目的最终目标是利用新获得的花粉生产力估计值重建过去几十年的区域草原植被。调查人员将从弗林特山的一个大湖中获取沉积物岩心。过去50年的花粉组合将从沉积物中量化，盆地周围的土地覆盖也将从航空照片和遥感数据中得到量化。总体而言，这项研究将改进对草原植被和气候过去如何相互作用以及它们未来可能如何相互作用的解释。随着人类对草原生物群的压力增加，这种知识变得越来越重要。美国大平原的大部分经济依赖于草原对气候变化的适应能力。该项目的结果将有助于了解草原组成和生产力如何对过去的气候变化做出反应。它还将提供有关该地区居民认为不受欢迎的两个趋势的信息，即木本植物扩张的原因以及与大气中致敏原花粉相关的因素。研究项目的很大一部分将培训本科生和研究生开展实地和实验室活动。利用堪萨斯州立大学的女性工程和科学项目开发的基础设施，研究人员将参与对K-12女孩感兴趣的科学的外联活动。该项目产生的数据将与北美花粉数据库共享，供其他研究人员使用。

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.