Effects of long-term elevated CO2 on earthworm populations, bioturbation and carbon sequestration in soils

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。人类活动最显著的全球影响之一是大气中二氧化碳（CO2）浓度的急剧增加。大气CO2浓度升高通过促进植物生长对植被产生直接影响，并通过对消耗植物残体的土壤生物产生级联效应产生间接影响。蚯蚓被认为是最重要的土壤生物群体之一，因为它们大量加工植物材料，将植物来源的碳纳入土壤并使其稳定，以及土壤混合活动。蚯蚓活动可以通过控制处理的碳量和将植物材料在土壤深处混合来影响土壤中的碳固存，从而影响这种植物来源的碳在土壤中保留的时间。该项目旨在了解：（1）植物对CO2浓度升高的反应如何影响蚯蚓种群，（2）在暴露于CO2浓度升高的森林中，蚯蚓介导的土壤混合是否增加或减少，以及（3）这些综合效应如何影响土壤碳固存。研究人员建议将联合收割机地球化学技术与生态学方法相结合，以推断蚯蚓对土壤混合和碳固存的作用。这项研究将在橡树岭国家实验室的一个温带落叶林中进行，该森林自1998年以来一直暴露在CO2浓度升高的环境中。为了研究CO2浓度升高对蚯蚓的影响，将暴露于CO2浓度升高的复制森林样地中蚯蚓物种的密度和生物量与环境CO2条件下的蚯蚓物种进行比较。研究人员将使用稳定和放射性同位素作为化学标记物，并将测量特定植物成分的生物标记物（即，叶和根），以确定土壤中的单独混合层，并提供更准确的知识，植物来源的碳在这些森林土壤中的命运。该项目的结果将有助于了解生物和土壤过程之间的反馈和相互作用，这些过程决定了生态系统中碳固存的程度。具体而言，该项目将：（1）提供关于CO2浓度升高和全球变化对温带森林的级联效应的新信息，（2）量化蚯蚓在土壤混合和碳固存中的作用，（3）应用放射性同位素研究全球变化对土壤过程的影响的新方法，以及（4）产生重要的功能数据，这将为碳循环和全球变化研究中的生态学提供前所未有的背景。这一建议的一个重要成果将是将可持续发展研究纳入芝加哥公立学校高中正在进行的科学教育活动，这些学校来自为代表性不足的群体服务的地区。 此外，该项目的资金将扩大参与科学，并代表了PI的就业机会，PI是一个开始的调查员，以及来自伊利诺伊大学芝加哥的本科生将参与这项研究，为他们提供独特的经验，在科学与现实世界的影响。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).One of the most pronounced global effects of human activity is the sharp increase in atmospheric carbon dioxide (CO2) concentration. Elevated atmospheric CO2 concentration has a direct impact on vegetation through increasing plant growth and an indirect impact through cascading effects on soil organisms that consume plant residues. Earthworms are considered one of the most important groups of soil organisms due to their substantial processing of plant material, incorporation and stabilization of plant-derived carbon in soils, and soil-mixing activities. Earthworm activities can affect carbon sequestration in soils by controlling the amount of carbon that is processed and by mixing the plant material deep in the soil, thereby influencing the amount of time that this plant-derived carbon remains in the soil. This project seeks to understand: (1) how plant responses to elevated CO2 have affected earthworm populations, (2) whether earthworm-mediated soil mixing has increased or decreased in forests exposed to elevated CO2, and (3) how these combined effects influence soil carbon sequestration. The investigators propose to combine geochemical techniques with ecological methodologies to make inferences about the role of earthworms on soil mixing and carbon sequestration. The study will be conducted in a temperate deciduous forest exposed to elevated CO2 since 1998 at Oak Ridge National Laboratory. To study the effects of elevated CO2 on earthworms, the densities and biomass of earthworm species in replicated forest plots exposed to elevated CO2 will be compared with those at ambient CO2 conditions . The investigators will use stable and radioactive isotopes as chemical markers and will measure biomarkers for specific plant components (i.e., leaves and roots) to identify separate mixing layers within the soil and to provide a more accurate knowledge of the fate of plant-derived carbon in these forest soils.The results from this project will contribute new knowledge about feedbacks and interactions among biological and soil processes that determine the degree of carbon sequestration in an ecosystem. Specifically this project will: (1) provide new information on cascading effects of elevated CO2 and global change on temperate forests, (2) quantify the role of earthworms on soil mixing and carbon sequestration, (3) apply a novel method using radioisotopes to study the effects of global change on soil processes, and (4) generate important functional data that will provide an unprecedented context for earthworm ecology in carbon cycling and global change research. An important outcome of this proposal will be the incorporation of earthworm research in on-going science education activities in high schools of Chicago public schools from districts that serve mostly underrepresented groups. In addition, funding for this project will broaden participation in science, and represent an employment opportunity for the PI, who is a beginning investigator, as well as for undergraduate students from the University of Illinois at Chicago who will participate in this research, providing them unique experiences in science with real-world implications.