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 soilrespiration 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.
