Granivores and the Composition of Experimental Grass and Forb Communities

9420860豪这项研究将探讨是否种子吃鸟类，种子和树叶吃啮齿动物影响群落结构的高草草原。我们的目标是确定是否可预测的觅食行为有可预测的后果模型高草群落的组成和优势。为此，研究人员将建立受控群落的植物物种分层的种子大小，形式和物候。防止脊椎动物的地块应显示大种子物种和双子叶植物的优势。啮齿类动物可接近的地块应显示啮齿类动物喜爱的种子植物幼苗的覆盖面积下降，而鸟类可接近的地块应显示种子植物的覆盖面积和幼苗在其最佳处理范围内的下降。暴露于两者的地块将由具有最小、最不理想种子的物种主导。为了完善预测，PI将整合处理地块上和处理地块外的脊椎动物种群普查，以及对12种植物种子或叶子上的常见鸟类、小鼠和田鼠的选择性试验。选择性的排名将决定种子偏好是否符合基于种子大小和/或遭遇率的觅食理论的预测。种子和叶子选择性的排名也将提供关键动物物种可能如何影响田间植物群落的具体预测。现场和场外脊椎动物种群的一致性评价将允许评估处理的影响，与鸟类和哺乳动物的场外影响进行比较。

9420860 Howe This study will examine whether seed-eating birds, and seed-eating and foliage-eating rodents influence community structure of tallgrass prairie. The objective is to determine whether predictable foraging behaviors have predictable consequences for composition and dominance in model tallgrass communities. To do so, the investigators will establish controlled communities of plant species stratified by seed size, form, and phenology. Plots protected from vertebrates should show dominance of large-seeded species and dicots. Plots accessible to rodents should show a depression in cover of seedlings of plant with seeds favored by rodents, while plots accessible to birds should show a depression in cover and seedlings of plant with seeds in their optimal handling range. Plots exposed to both will be dominated by species with the smallest, least desirable seeds. To refine predictions, the PIs will integrate censuses of vertebrate populations on and off the treatment plots with selectivity trials of common birds, mice, and voles on seeds or foliage of 12 plant species. Ranking of selectivities will determine whether seed preferences conform to predictions of foraging theory based on seed size and/or encounter rate. Rankings of seed and foliage selectivities will also provide specific predictions of how key animal species are likely to influence plant communities in the field. Concordant evaluation of on-site and off-site vertebrate populations will permit assessment of influences of treatments as compared with off-site effects of birds and mammals.