Collaborative Proposal: MSA: Predicting the effects of nitrogen deposition on the soil carbon sink with a continental-scale experiment

合作提案：MSA：通过大陆规模的实验预测氮沉降对土壤碳汇的影响

• 批准号: 1925781
• 负责人: John Stark
• 金额: $ 9.36万
• 依托单位: Utah State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1925781&HistoricalAwards=false
• 关键词: Collaborative; Proposal; MSA; Predicting; effects

To predict how ecosystems will respond to ongoing environmental change, it is critical to understand how biogeochemical cycles of carbon (C) and nitrogen (N) interact with one another. N availability influences the movement of C among its three major terrestrial pools: plants, soils, and the atmosphere, where concentrations of CO2 are increasing. Similarly, human activities have doubled the quantity of reactive N in the biosphere. To understand interactions between global N and C cycles, ecologists need to be able to predict the effects of N fertilization on soil organic matter, which is the largest reservoir of terrestrial C. At some sites, excess N accelerates the decomposition of soil C, promoting release of CO2; whereas at other sites, N fertilization appears to do the reverse, and promote soil C stabilization. This research will provide the first experiment that will test a new theory to explain these seemingly contradictory responses. This work is directly relevant to the development of terrestrial ecosystem models, which represent our most important tools to forecast when and where human disruption of the N cycle will amplify soil C-climate feedbacks. The research will also provide a platform to engage with groups traditionally underrepresented in ecological research, supporting hands-on research opportunities for first-generation Native American college students. The conceptual framework tested in this proof-of-concept study rests on the idea that N fertilization has opposing effects on two pools of soil organic matter with distinct biogeochemical controls: unprotected particulate organic matter (POM) vs. microbially inaccessible mineral-associated organic matter (MAOM). N fertilization should affect the balance between POM losses and MAOM gains in a predictable manner that is contingent on soil edaphic and biotic properties. This research will leverage steep gradients of soil geochemistry and climate to quantify soil C responses to altered N supply and soil pH (which is strongly influenced by N fertilization). The experimental approach will utilize both stable isotope tracer approaches and a complementary, standardized "synthetic soil" method to quantify fluxes of C and N among the microbial biomass, POM, and MAOM pools. The researchers will synthesize responses observed in short-term laboratory studies and longer-term field-based fertilization experiments to quantify how environmental drivers operating at local to regional scales mediate changes in soil C cycling under N fertilization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

为了预测生态系统将如何响应持续的环境变化，了解碳（C）和氮（N）如何相互作用的生物地球化学周期至关重要。 n可用性影响C在其三个主要的陆地池中的运动：植物，土壤和大气，其中二氧化碳浓度正在增加。同样，人类活性在生物圈中的反应性n量增加了一倍。要了解全球N和C周期之间的相互作用，生态学家需要能够预测氮肥对土壤有机物的影响，这是陆地C的最大储层。在某些地点，过量的N加速了土壤C的分解，促进了促进的土壤。释放二氧化碳；而在其他部位，n受精似乎可以反向，并促进土壤稳定。这项研究将提供第一个实验，该实验将测试一种新理论来解释这些看似矛盾的回答。这项工作与陆地生态系统模型的开发直接相关，这代表了我们最重要的工具，以预测人类对N周期的破坏将扩大土壤C气候反馈的何时何地。这项研究还将提供一个平台，以与传统上在生态研究中代表性不足的团体互动，从而为第一代美国原住民大学生提供动手研究机会。 在本概念验证研究中测试的概念框架取决于以下观点：n受精对两个具有不同生物地球化学控制的土壤有机物质具有相反的影响：未受保护的颗粒有机物（POM）与微生物不可接受的矿物质相关有机物有机物（MAOM）。 n受精应以可预测的方式影响POM损失和MAOM增益之间的平衡，这取决于土壤质子和生物性特性。这项研究将利用土壤地球化学和气候的陡峭梯度来量化土壤c对改变n供应和土壤pH的反应（这受到n受精的强烈影响）。实验方法将使用稳定的同位素示踪剂方法和互补的，标准化的“合成土壤”方法来量化微生物生物量，POM和MAOM池中C和N的通量。研究人员将综合在短期实验室研究中观察到的反应和长期的基于现场的受精实验，以量化在n受精下介导土壤C循环的环境驱动因素如何介导NSF的统计任务，并具有NSF的统计任务，并具有使用基金会的知识分子优点和更广泛的审查标准，被认为值得通过评估来支持。