The Joint Effects of Herbivory and Competition Upon Plant Communities

食草和竞争对植物群落的共同影响

• 批准号: 8704625
• 负责人: Norma Fowler
• 金额: $ 23.54万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-01-01 至 1991-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8704625&HistoricalAwards=false
• 关键词: Joint; Effects; Herbivory; Competition; Upon

This proposal by Dr. Norma Fowler of the University of Texas, Austin is to examine the combined influences of grazing and interplant competition on plant community structure. The effects of grazing upon plants are not limited to the effects of defoliation, but include the effects of trampling, and urine and dung deposition. Investigation of these secondary effects will not be done. Initially, the investigation will concentrate upon the effects of defoliation. However, each of the field experiments will include both a (fenced) clipping treatment and an (unfenced) grazing treatment as well as a (fenced) control; differences between the clipping and grazing treatments may be due to these secondary effects, or perhaps to differentiate between mechanical clipping and the action of an animal's jaw. An absence of differences between the clipping and grazing treatments will support the null hypothesis that in this system the effects of grazing are largely limited to the direct effects of tissue removal. A clipping treatment will be included in these experiments, not only to test this hypothesis, but also because the effects of grazing are also a function of animal preferences for plants of different species, sizes, physiological and developmental states, surrounding vegetation, and so on. An apparent interaction effect between competition and defoliation can arise from the effects of preference, when none is actually present. Estimates of preference will be made and the results used to indicate appropriate additional experimental treatments. This work has much intrinsic, ecological interests, but its immediate practical value is in its importance for understanding plant community maintenance, especially in over-grazing situations in nutrient poor prairies, savannas, etc.

这一建议是由弗吉尼亚大学的诺玛·福勒博士提出的， 德克萨斯州， 奥斯汀将研究放牧和 种间竞争对植物群落结构的影响。 的影响 放牧对植物的影响不仅限于 落叶，但包括践踏的影响，尿和 粪便沉积 对这些副作用的研究将 还没完 最初，调查将集中在 落叶的影响。 然而，每个领域 实验将包括（围栏）修剪处理和 （非围栏）放牧处理和（围栏）对照; 修剪和放牧处理之间的差异可能是 由于这些副作用，或者可能是为了区分 和动物下颚的动作之间的联系 修剪和放牧之间没有区别 治疗将支持零假设，在这个系统中， 放牧的影响很大程度上仅限于直接影响 组织切除的过程 夹闭治疗将包括在 这些实验不仅是为了验证这一假设， 因为放牧的影响也是动物 对不同种类、大小、生理特性的植物 和发展状态，周围的植被，等等。 竞争与落叶交互作用明显 可以从偏好的影响中产生，而实际上没有一个是 礼物 将进行偏好估计， 用于指示适当的附加实验处理。 这项工作有很多内在的，生态的利益，但它 直接的实用价值在于它对于理解 植物群落的维持，特别是在过度放牧 营养贫乏的大草原、热带稀树草原等的情况。