Genetic Variation and Herbivory in Aspen: Consequences for Ecosystem Processes

科学家们早就知道植物种群中存在遗传变异，但这种生物多样性来源对基本生态系统过程(例如，碳和氮循环)的重要性知之甚少。生态系统科学的另一个鲜为人知的方面是森林食草动物，如害虫，如何影响营养循环。当昆虫食草动物进食时，它们会引起植物体内的化学变化，并改变土壤中有机物的输入。这些影响反过来可能影响影响森林健康的基本生态属性，以及森林从大气中吸收碳的能力。这一提议通过植物化学的共同分母整合了两个主要主题--遗传变异和食草动物的生态系统后果。本研究的目的是研究种内遗传变异和食草性对基本生态系统过程(分解和养分循环)的独立和交互影响。我们将使用颤杨作为模式系统，因为它具有广阔的地理范围和生态重要性，而且因为杨树在植物化学中表现出惊人的遗传变异，并且容易发生戏剧性的落叶事件。我们的方法将涵盖从土壤、微生物和纯化化学提取物的短期室内实验，到研究天然杨树林中养分循环的长期多年实验。这项研究将对生物多样性对森林生态系统功能的重要性提供基本的新见解，从而为参与林地管理的州和联邦机构的政策提供参考。此外，这项工作还将有助于本科生和博士后的科学技术培训。

Scientists have long known that genetic variation exists within plant populations, but the importance of this source of biological diversity for basic ecosystem processes (e.g., carbon and nitrogen cycling) is poorly understood. Another poorly recognized aspect of ecosystem science is how forest herbivores, such as insect pests, influence nutrient cycles. As insect herbivores feed, they induce chemical changes in plants and alter inputs of organic matter to the soil. These impacts in turn are likely to influence basic ecological properties that influence forest health, and the capacity of forests to take up carbon from the atmosphere. This proposal integrates two major themes - the ecosystem consequences of both genetic variation and herbivory - through the shared common denominator of plant chemistry. The purpose of this research is to investigate the independent and interactive effects of within-species genetic variation and herbivory on basic ecosystem processes (decomposition and nutrient cycling). We will use trembling aspen as a model system because of its expansive geographic range and ecological importance, and because aspen expresses striking genetic variation in plant chemistry and is subject to dramatic defoliation events. Our methods will span the range from short-term chamber experiments with soil, microorganisms, and purified chemical extracts, to long-term multi-year experiments that investigate nutrient cycling in natural aspen stands. This research will provide fundamental new insights into the importance of biodiversity to forest ecosystem function, and thereby inform policies of state and federal agencies involved in management of forest lands. Moreover, this work will contribute to the scientific and technical training of undergraduate and postdoctoral students.