DISSERTATION RESEARCH: Tracking Ecosystem Nitrogen Cycling in Black Spruce Forests with Novel15N Measurements

论文研究：利用新颖的 15N 测量追踪黑云杉森林的生态系统氮循环

• 批准号: 0909764
• 负责人: Edward Schuur
• 金额: $ 1.48万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2010-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0909764&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Tracking; Ecosystem; Nitrogen

The dynamics of many terrestrial and aquatic ecosystems are controlled by the availability of nitrogen (N), which is often in short supply in the environment. Human activities are increasing N availability in ecosystems both by increasing N inputs through fertilizer addition or atmospheric deposition, and by speeding up internal recycling of N as a result climate warming or landscape modification. While more N can increase biological productivity, this has a significant impact on the structure and function of natural ecosystems that have been shaped by low nutrient conditions for thousands of years. Recently, researchers have sought to use stable isotopes of N --a measurement method that can distinguish between different forms of N-- in plant leaves to understand ecosystem N dynamics. Relatively straightforward measurements of leaf N isotopes at a single point in time record the net effect of multiple complex biological and physical transformations that occur over time as N moves throughout whole ecosystems. This doctoral dissertation research project will make mechanistic measurements of N cycling across a range of Alaskan black spruce forests to provide an underpinning to the interpretation of leaf N isotope made at the same sites. Here, natural gradients of soil fertility in combination with experimental fertilizer additions and analytical modeling will be used to explore and interpret the patterns of leaf N isotopes. These results will help inform the response of natural ecosystems to a changing N cycle. The graduate student, in addition to performing research, will be mentoring and undergraduate research assistant. This study will help better understand the impact of climate change on natural ecosystems.

许多陆地和水生生态系统的动态受到氮(N)有效性的控制，而环境中的氮往往是短缺的。人类活动正在通过增加化肥或大气沉积来增加氮的投入，以及通过加快气候变暖或景观改变导致的氮的内部循环，来增加生态系统中的氮素有效性。虽然更多的氮可以提高生物生产力，但这对数千年来因低营养条件而形成的自然生态系统的结构和功能产生了重大影响。最近，研究人员试图使用N的稳定同位素--一种可以区分植物叶片中不同形态N-的测量方法--来了解生态系统N的动态。在单个时间点对叶片N同位素的相对直接测量记录了随着N在整个生态系统中的移动而随着时间的推移发生的多种复杂的生物和物理变化的净影响。这项博士论文研究项目将对一系列阿拉斯加黑云杉森林中的N循环进行机械测量，为解释在相同地点进行的树叶N同位素提供基础。在这里，土壤肥力的自然梯度，结合实验化肥添加和分析模型，将被用来探索和解释叶片N同位素的模式。这些结果将有助于了解自然生态系统对变化的N循环的反应。这名研究生除了从事研究外，还将担任导师和本科生研究助理。这项研究将有助于更好地了解气候变化对自然生态系统的影响。