Collaborative Research: Linking the chemical structure of black carbon to its biological degradation and transport dynamics in a northern temperate forest soil

火是陆地生态系统中碳(C)循环的主要控制器，通过将植物生物质转化为大气中的二氧化碳，并通过向土壤贡献未完全燃烧的生物质或“黑碳”(BC)。对BC在陆地生态系统中的短期和长期命运的科学理解是不完整的，我们对BC在环境中的命运的理解存在着关键的知识鸿沟。BC，可能会显著影响土壤碳储量和森林与大气的二氧化碳交换速率。通过综合实地和实验室研究，这项研究将增进对北方森林土壤中BC降解和运输过程的基本生物、化学和物理控制的了解。这项研究将把BC物质的炭化温度与其化学和物理结构以及由此产生的衰减率、主要分解物的活性、酶活性、运输动力学和土壤中的稳定机制联系起来。拟议的实验方法将使用在一定温度范围内(200至600摄氏度)生产的稳定的同位素浓缩(13C和15N)BC材料及其前体木材--北美东部一种易起火且资源丰富的树种--杰克松，以阐明BC材料的结构，并追踪这些材料加入土壤后的多种命运。这种方法将允许使用先进的分子和光谱技术直接评估土壤中的生物周转。这项工作将第一次看到特定的微生物和土壤动物在土壤中BC和木材的分解和移动中所起的作用。为了测试植物种类对BC化学和物理结构的影响，将红枫的高13C和15N富集型BC与短叶松进行比较。由此产生的数据和知识将有助于正在进行的陆地碳循环预测工作，并将为生态系统和气候建模人员以及土地利用管理人员提供信息。大多数现有气候模型预测，在未来气候变暖的情况下，温带和北方森林将经历更高的火灾频率，从而增加对土壤的BC(黑碳)贡献。此外，能源行业预计将生产大量的BC(或“生物炭”)。这项研究将描述土壤中BC和木材降解过程的关键生物、化学和物理控制，从而大大增加我们对易着火森林中碳的稳定和固定的机制的了解。这将为改进生态系统和全球碳循环模型及其在描述当前和未来气候下森林土壤碳汇的使用提供所需的信息。这项研究将为对生态系统功能、生产力和可持续性感兴趣的广泛的科学、教育、土地管理者和机构社区提供信息。此外，该项目将包括纽约市一所为少数族裔服务的高中的一名科学教师的参与，以及纽约全球地铁计划，将应用环境生态系统科学和地球科学纳入高中生物学和地球科学课程。普渡大学将与利奇湖部落学院(LLTC)合作，将这项研究整合到民族生物学课程中，重点关注现代化学原理和美洲原住民对卑诗省的利用。密歇根大学生物站和纽约城市大学将分别在该项目范围内培训一名博士后研究员，并将把实地研究作为现场大学课程、基于现场的本科生和研究生研究项目以及科学推广的资源。

Fire is a major controller of carbon (C) cycling in terrestrial ecosystems, by converting plant biomass to atmospheric CO2 and by contributing incompletely combusted biomass or "black carbon" (BC) to soils. The scientific understanding of the short- and long-term fates of BC in terrestrial ecosystems is incomplete, and a critical knowledge gap exists in our understanding of the fate of BC in the environment. BC, may significantly affect soil C stocks and rates of CO2 exchange of forests with the atmosphere. Through integrated field and laboratory studies, this research will improve understanding of fundamental biological, chemical and physical controls on BC degradation and transport processes in a northern forest soil. This research will link the charring temperature of BC materials to their chemical and physical structures and their resulting decay rates, activity of the main decomposers, enzyme activities, transport dynamics, and stabilization mechanisms in soil. The proposed experimental approach will use stable isotope-enriched (13C and 15N) BC materials produced over a range of temperatures (200 to 600ºC) and its precursor wood of jack pine, a fire-prone and abundant tree species in eastern North America, to elucidate the structures of BC materials and track the multiple fates of these materials when added to soil. This approach will permit a direct assessment of the biological turnover in soil using advanced molecular and spectroscopic techniques. This work will provide the first look at the roles of specific groups of microorganisms and soil fauna involved in the decomposition and movement of BC and wood in soils. To test the effects of plant species on BC chemical and physical structures, highly 13C- and 15N-enriched BC from red maple will be compared with the jack pine. Resulting data and knowledge will contribute to ongoing efforts to predict terrestrial C cycling, and will inform ecosystem and climate modelers and also land use managers.Most existing climate models predict that temperate and boreal forests will experience greater fire frequency under a warmer future climate, thereby increasing BC (black carbon) contributions to soils. In addition, substantial BC (or "biochar") production is expected from the energy industry. This research will characterize the key biological, chemical and physical controls on BC and wood degradation processes in soils, thereby substantially increasing our understanding of the mechanisms involved in C stabilization and sequestration in fire-prone forests. This will provide information needed to improve ecosystem and global C cycling models and their uses in characterizing forest soil C sinks in present and future climates. This research will inform a broad scientific, educational, land manager and agency community interested in ecosystem function, productivity and sustainability. In addition, the project will include involvement of a science teacher from a New York City minority-serving high school and the NY GLOBE Metro program to integrate applied environmental ecosystem science and geosciences into the high school biology and earth science curricula. Purdue University, in collaboration with Leech Lake Tribal College (LLTC), will integrate this research into an ethnobiology curriculum focusing on both modern principles of chemistry and Native American utilization of BC. The University of Michigan Biological Station and City University of New York will each train a postdoctoral researcher within the scope of this project and will use the field study as a resource for on-site university courses, its site-based undergraduate and graduate student research programs, and its science outreach.