RUI: Ecosystem responses to atmospheric N deposition in an ombrotrophic bog: vegetation and microclimate feedbacks lead to stronger C sink or source?

RUI：生态系统对缓营养沼泽中大气氮沉积的响应：植被和小气候反馈导致更强的碳汇或碳源？

• 批准号: 1019523
• 负责人: Jill Bubier
• 金额: $ 88.46万
• 依托单位: Mount Holyoke College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1019523&HistoricalAwards=false
• 关键词: RUI; Ecosystem; responses; atmospheric; deposition

The increase in atmospheric nitrogen (N) deposition from industrial pollution is of major concern in northern ecosystems, which are typically nutrient-limited. Previous studies have hypothesized that N deposition may increase the carbon dioxide (CO2) sink potential of northern ecosystems by stimulating plant productivity. Peatlands, in particular nutrient-limited bogs, have accumulated vast amounts of carbon (C) since deglaciation, yet the annual C balance is often a very small difference between plant production and soil decomposition. The main objective of this research is to improve our understanding of complex feedbacks between peatland ecosystems and the atmosphere in response to increasing atmospheric N deposition and climate change. Will N deposition enhance or diminish the CO2 sink potential of nutrient-limited bog ecosystems? What are the positive and negative feedbacks of N deposition to net ecosystem CO2 exchange and climate change? How do changes in vegetation function and structure, as well as corresponding changes in microclimate (moisture, temperature, light interception), contribute to changes in the carbon balance? How will changes in leaf chemistry, phenology, and plant function affect the seasonality of CO2 exchange? The overall framework for the research addresses 1) the impacts of N deposition on global atmosphere-biosphere interactions, and 2) the vulnerability of peatland ecosystems to become C sources rather than long-term C sinks. The project builds on 10 years of research and education at a long-term fertilization experiment with varying levels of nitrogen, phosphorus, and potassium at Mer Bleue Bog in Ottawa, Ontario, Canada. The measurements and experiments include several field and laboratory components: ecosystem and leaf-level CO2 gas exchange of mosses and vascular plants at a range of light levels, leaf biochemistry to test stress responses to potential N saturation, above and belowground plant production and decomposition, and microclimate within the plant canopy and soil profile. These data will contribute to a peatland ecosystem model that will improve our ability to predict thresholds of change in these globally important ecosystems.The broader impacts of this project include training women undergraduates at Mount Holyoke College, to prepare them for graduate school and future careers in environmental science. The plan includes a cascade mentoring model, which trains students to become research collaborators by following the sequence of trainee during the first summer, mentor to new undergraduate research assistants in the second summer, and finally designers of scientific studies and authors of honors research theses, leading to presentations at international scientific meetings and publication in peer-reviewed journals. Strong collaborations with scientists from major research universities in Canada, Finland and the U.S. are essential for training undergraduates. By involving these students in vibrant research communities of graduate students, postdoctoral fellows and faculty, they will contribute to our understanding of the complexities of carbon and nitrogen cycling in northern peatlands through interdisciplinary research.

工业污染引起的大气氮沉降的增加是北方生态系统的主要问题，因为北方生态系统通常是营养有限的。以往的研究假设，氮沉降可能会增加二氧化碳（CO2）汇潜力的北方生态系统通过刺激植物生产力。 泥炭地，特别是营养有限的沼泽，自冰川消退以来积累了大量的碳（C），但每年的碳平衡往往是植物生产和土壤分解之间的一个非常小的差异。 这项研究的主要目的是提高我们的理解泥炭地生态系统和大气之间的复杂反馈，以应对大气氮沉降和气候变化的增加。 氮沉积会增强还是减弱营养有限沼泽生态系统的CO2吸收潜力？氮沉降对生态系统CO2净交换和气候变化的正反馈和负反馈是什么？ 植被功能和结构的变化，以及相应的小气候变化（水分、温度、光截获）如何促成碳平衡的变化？ 叶片化学、物候和植物功能的变化将如何影响CO2交换的季节性？ 研究的总体框架解决1）全球大气-生物圈相互作用的N沉降的影响，和2）泥炭地生态系统的脆弱性，成为C源，而不是长期的C汇。 该项目建立在加拿大安大略渥太华的Mer Bleue Bog进行的长期施肥实验的10年研究和教育基础上。 测量和实验包括几个领域和实验室的组成部分：生态系统和叶水平的苔藓和维管植物在一系列的光水平，叶生物化学测试压力响应潜在的氮饱和度，地上和地下植物生产和分解，以及植物冠层和土壤剖面内的小气候的CO2气体交换。这些数据将有助于泥炭地生态系统模型，这将提高我们预测这些全球重要生态系统变化阈值的能力。该项目的更广泛影响包括培训霍利奥克山学院的女本科生，为她们进入研究生院和未来从事环境科学职业做好准备。 该计划包括一个级联辅导模式，培养学生成为研究合作者，按照第一个夏天的实习生顺序，在第二个夏天指导新的本科生研究助理，最后是科学研究的设计者和荣誉研究论文的作者，导致在国际科学会议上发表演讲并在同行评审的期刊上发表。 与来自加拿大，芬兰和美国主要研究型大学的科学家的密切合作对于培养本科生至关重要。 通过让这些学生参与研究生，博士后研究员和教师的充满活力的研究社区，他们将有助于我们通过跨学科研究了解北方泥炭地碳和氮循环的复杂性。