REU: Effects of Bison Herbivory on Two Tallgrass Prairie Species: The Influence of Fire, Neighbors, and Pattern of Defoliation on Plant Response

食草动物对植物适应性、种群动态和群落结构具有重要影响。植物对草食的反应在一个连续体上变化，这取决于落叶的时空模式和落叶植物的竞争邻居或物理环境。本研究将评估野牛食草对高草（Panicum virgatum和Andropogon gerardii）分蘖生长、繁殖、克隆传播和存活的影响；确定竞争对手、落叶时空格局和火灾对草原植物对野牛食草反应的相互作用。这些研究将验证这样的假设，即火的影响和生物邻域变化改变了对放牧的反应，以及不同物种在不同的火制度下的相对放牧耐受性发生了变化。将测量两个生长季节的营养生长、种子繁殖和无性系生长性能以及植物反应，以确定草食对个体和种群的长期影响，以及单一草食动物是否会对不同的植物生活史阶段产生相反或一致的影响。这些实验将研究食草对草本植物和植物生长形式的直接影响，以及非生物和生物相互作用如何影响植物对食草的反应。他们还将深入了解放牧和火灾对高草草原多年生植物的相互作用，以及其对个体克隆成功和物种相对丰度的影响。这个拟议的项目是一个长期研究计划的一部分，该计划将更全面地解决物种之间和年份之间对草食反应的变化模式。

Herbivores can strongly influence plant fitness, population dynamics, and community structure. Plant responses to herbivory vary along a continuum depending on the spatial/temporal patterns of defoliation and the competitive neighborhood or physical environment of the defoliated plant. The proposed research will 1) assess the consequences of bison herbivory on tiller growth, reproduction, clonal spread, and survivorship of tallgrasses (Panicum virgatum and Andropogon gerardii) and 2) determine the interacting effects of competitors, spatial and temporal patterns of defoliation, and fire on plant responses to bison herbivory on a prairie. The studies will test the hypothesis that the effects of fire and biotic neighborhood variation alter responses to grazing and that the relative grazing tolerances of different species change under different fire regimes. Vegetative growth, seed reproduction, and clonal growth performance, and plant responses over two growing seasons will be measured to determine long-term effects of herbivory on individuals and populations and whether a single herbivore may have opposite or congruent effects on different plant life history stages. These experiments will examine proximal consequences of herbivory on herbaceous plants and plant growth form and how abiotic and biotic interactions influence plant responses to herbivory. They will also provide insight into the interactions of grazing and fire effects on tallgrass prairie perennials, and its consequences for individual clone success and species relative abundances. This proposed project is part of a longer-term research program that will more fully address patterns of variation in responses to herbivory among species and among years.