Collaborative Research: Watershed Carbon Distribution and Flux Across Environmental Gradients

二氧化碳（CO2）在气候变化和土壤碱性阳离子去除中的核心作用已经确立。然而，对集水区土壤CO2产生和外排的时空变化仍知之甚少。我们刚刚开始开发方法，从通量塔或呼吸室等点测量扩展到更大的空间尺度，如地块或流域。主要的二氧化碳强迫因子如何在气候、环境、生物地球化学和地形梯度中变化需要解决。此外，在流域尺度上，地形对碳积累和溶解有机碳（DOC）动员控制的补充研究对于理解景观与碳循环之间的联系至关重要。许多关于碳分配和移动的研究都集中在大气交换上，而忽略了河流中碳的损失。最近的工作使我们深入了解了控制水流C输出的时间和大小的过程。我们认为，了解地形控制和河流-集水区的联系是理解集水区总碳通量的必要条件。生物地球化学相似度的概念与水文相似度相关，已被认为是理解生物地球化学过程空间格局的有力工具。我们的研究将测试这一概念对土壤呼吸和DOC输出的适用性，并将确定量化土壤二氧化碳产生和地表外排的一阶控制中的时空变异性所需的关键测量集。然后，这些场衍生的信息将告知并约束我们的模型，该模型模拟这些参数在空间和时间上的可变性。这些空间分布的数据对模拟土壤二氧化碳的产生和运输至关重要。通过将广泛的现场测量和影响土壤呼吸的因素（如土壤温度、土壤湿度、土壤肥力和气候变量）的量化与数值模拟技术相结合，这项工作将为土壤与大气之间广泛但鲜为人知的水、碳和能量交换的测量和建模提供一条前进的道路。本研究的目标是：(1)量化CO2外排，并开发和应用集水区呼吸模型，包括土壤空气pCO2、溶解CO2的垂直土壤水分输送和地表CO2外排；(2)探索地形在多大程度上可以用来解释驱动呼吸的因素的内在变异性；(3)量化地形对流域土壤C分布和景观中链接C积累的控制。在流域尺度上DOC输运和河流DOC输出。这项工作将为理解土壤呼吸和由此产生的土壤空气CO2浓度、大气交换和径流C输出的时空变量的框架的发展和应用提供经验信息和基础。拟议活动所产生的更广泛影响。将本科生和研究生纳入研究的各个方面是这项工作的主要目标。弗罗斯特堡州立大学是一个以本科生为主的机构，因此，本科生获得研究经验的机会有限。这项研究将通过弗罗斯特堡州立大学、弗吉尼亚大学和蒙大拿州立大学（EPSCoR机构）之间的合作联系，为弗罗斯特堡学生提供现在和未来的经验和机会。学生将成为研究团队不可或缺的成员，并鼓励他们通过在国家会议上发表和介绍他们的发现来承担自己的贡献。这项研究将通过在课堂练习和实地学习中包含接近实时的数据来增强教学活动（本科生和研究生）。这项工作还将加强弗罗斯特堡的研究基础设施，帮助促进在水文学和生物地球化学领域代表性不足的本科院校的学生和教师。如果获得资助，大天空科学与自然史研究所同意为研究生参加BSI研究生研究员计划提供额外的支持。根据该计划，研究员将接受培训，以便有效地向K-12社区和公众传达他们的成果。研究员计划为研究生提供培训和交流科学的机会，鼓励年轻科学家了解他们在向公众传播科学发现方面的作用，并帮助实现BSI。我们的使命是将当前的研究与探究性学习相结合，为所有年龄和各行各业的人们提供服务。这项工作还将产生一个数据集，包括土壤空气二氧化碳浓度、外排、半分布式现场测量和模拟驱动因素，以及与径流碳输出的联系。我们的数据集将在网上免费提供给其他研究人员，并可作为二氧化碳产量、通量和径流C输出模型的测试数据集。到目前为止，还没有这样的数据集可供作者使用。然而，通过提供一个试验场和比较集，这对于理解C在环境梯度中的积累和通量至关重要。

0404130McGlynn Watershed carbon distribution and flux across environmental gradients The central roles of carbon dioxide (CO2) in climate change and the removal of base cations from soils has been established. However, the spatial and temporal variation of CO2 production and efflux from catchment soils remains poorly understood. We are just beginning to develop the methods to up-scale from point measurements such as those made by flux towers or respiration chambers to larger spatial scales such as plots or watersheds. How the primary CO2 forcing factors vary across climatic, environmental, biogeochemical, and topographic gradients needs to be addressed. In addition, complementary investigation of the topographic controls on C accumulation and the mobilization of dissolved organic carbon (DOC) s central to understanding the links between the landscape and the C cycle at the watershed scale. Many investigations of C allocation and movement focus on atmospheric exchange, neglecting the loss of C in stream water. Recent work has given us insight into the processes controlling the timing and magnitude of stream water C exports. We believe that understanding topographic controls and stream-catchment connections are integral to understanding total C flux from catchments. The concept of biogeochemical similarity, related to hydrological similarity, has been identified as a powerful tool in understanding the spatial patterns of biogeochemical processes. Our research will test the applicability of this concept for soil respiration and DOC export and will identify the critical set of measurements necessary to quantify the spatial and temporal variability in the first-order controls on soil CO2 production and surface efflux. This field-derived information will then inform and constrain our model that simulates the variability of these parameters through space and time. These spatially distributed data are central to simulation of the production and transport of soil CO2. By combining extensive field measurements and quantification of the factors influencing soil respiration such as soil temperature, soil moisture, soil fertility, and climatic variables with numerical modeling techniques, this work will provide a way forward for measuring and modeling the extensive but poorly understood exchange of water, C, and energy between soils and the atmosphere. The objectives of this research are (1) to quantify CO2 efflux and to develop and apply a model of catchment respiration, incorporating soil air pCO2, vertical soil water transport of dissolved CO2, and surface CO2 efflux, (2) to explore the extent to which topography can be used to explain the variability inherent in the factors driving respiration, and (3) To quantify the topographic controls on the distribution of soil C in the watershed and link C accumulation in the landscape, DOC transport, and stream DOC export at the watershed scale. Intellectual merit of the proposed activity This work will provide empirical information and the foundation for development and application of a framework for understanding the spatial and temporal variably of soil respiration and resultant soil air CO2 concentration, atmospheric exchange, and streamwater C export. Broader impacts resulting from the proposed activity. The inclusion of undergraduates and graduate students in all aspects of research is a primary goal of this work. Frostburg State University is a predominantly undergraduate institution, and as such, has limited opportunities for undergraduates to obtain research experience. This research will provide Frostburg students, both now and in the future with experience and opportunities through collaborative linkages made between Frostburg State University, The University of Virginia, and Montana State University (EPSCoR institution). Students will be integral members of the research team and will be encouraged to take ownership of their contributions through publication and presentation of their findings at national meetings. This research will enhance teaching activities (undergraduate and graduate) through inclusion of near real-time data in class exercises and field-based learning. This work will also strengthen the research infrastructure at Frostburg, helping to advance students and faculty from undergraduate institutions that are underrepresented in the fields of hydrology and biogeochemistry. If funded, the Big Sky Institute for Science and Natural History has agreed to provide additional support for participation of a graduate student in the BSI Graduate Fellows Program. Under that program, the Fellow would receive training in effective communication of their results to K-12 communities and the public. The fellows program provides graduate students training and opportunities to communicate science, encourages young scientists to understand their role in disseminating scientific findings to the public, and helps fulfill BSI.s mission of combining current research with inquiry-based learning for people of all ages and all walks of life. This work will also produce a dataset of soil air CO2 concentrations, efflux, semi-distributed field measurements and simulations of driving factors through time, and links to streamwater C export. Our datasets will be made freely available on the web to other researchers and can serve as a test data set for models of CO2 production, flux, and streamwater C export. To date, no such dataset is available (to the authors. knowledge), yet this is critical to understanding C accumulation and flux across environmental gradients by providing a testing ground and comparison set.