This is a request to support a Chapman conference on "Soil-mediated drivers of coupled biogeochemical and hydrological processes across scales," to be held at Biosphere 2, Oracle, Arizona (the University of Arizona), from October 21-24, 2013. This conference will bring together scientists from soil systems sciences, hydrology, and biogeochemistry to discuss recent findings dealing with the role and importance of coupled hydrological and biogeochemical processes occurring in the soil system and its interfaces with adjacent compartments, such as groundwater, plants, and the atmosphere.
The conference is intended to broaden community involvement in Earth science research and engage young investigators in furthering the development of interdisciplinary Earth science agenda. The conference is open to all scientists interested in the proposed topics. Attention will be paid to attracting early career scientists and Ph.D. students working on topics at the interfaces between the different disciplines, and specifically target underrepresented groups.
Chapman conferences are intended for deeper discussions of specific topical areas of scientific interest. This Chapman conference was organized to review and discuss new strategies to observe and understand processes and drivers in the biogeosphere, particularly those related to coupled biogeochemical and hydrological processes in terrestrial systems. The topics presented at the meeting included transport and exchange processes of organic and gaseous compounds across the soil-water and soil-plant interfaces, monitoring strategies of soil-mediated processes and drivers from the local to the catchment scale, and the im- pact of soil formation and functions on eco- system services. These topics were addressed and intensively discussed by participants covering the fields of soil systems sciences, hydrology, and biogeosciences. One key conclusion was the need to better account for biogeochemical processes in soil systems and how they affect climate variables and climate variability. Attendees identified the insufficient incorporation of biologically driven processes and their interplay with key soil processes and variables as a significant gap in scientists’ understanding of the terres- trial system. Because biological processes typically occur at the microscale, analyzing biogeochemical and water-related processes at multiple scales, in both space and time, becomes vital. For example, to better under- stand the dynamics of dissolved organic mat- ter in terms of its residence time and flow paths, scientists need to effectively link mea- surements with hydrological processes. Sev- eral speakers highlighted areas where these links could be improved. Several presenters spoke of the increasingly prominent roles of novel measurement tech- nologies, such as stable isotopes, in under- standing biogeochemical and hydrological processes. These processes include canopy carbon dioxide (CO2) exchange, evapotrans- piration, water flow and residence time at the catchment scale, soil carbon dynamics, and transport of dissolved organic matter in sub- surface and surface waters. Attendees dis- cussed the value of carbonyl sulfide as a new tracer to better separate soil and canopy CO2 fluxes. In addition, high temporal resolution and long-term measurements of stream water chemistry and concentrations of compounds in soil and gas phases were considered to be extremely helpful in identifying trends and underlying processes. Measurement technol- ogies are now available that provide these types of data and allow the identification of fractal scaling laws. A third area of consensus was on the need to establish and provide access to a world- wide network of critical zone observatories that provide long-term observation data on key soil processes and their interplay within the soil-plant-atmosphere system. To further a comprehensive understanding of critical zone dynamics, such observations must be com- bined with modeling activities to test hypoth- eses; to reveal feedbacks between soil, vegetation, and atmosphere; to upscale pro- cesses from the microscale to the field and catchment scales; and to predict future evolu- tion of the biogeosphere. Larger-scale manip- ulation experiments (e.g., deforestation, irrigation, land use changes) may help scien- tists better understand feedback mechanisms between the compartments of the critical zone. The observations then need to inform coupled biogeochemical and hydrological models (both conceptual and numerical) to extrapolate beyond the conditions used to validate or calibrate. The list of participants, agenda, and sum- maries of the breakout groups can be found at http://chapman.agu.org/soil-mediated/. Many oral presentations delivered during the sessions can be found at www.ites-web. ethz.ch/index.php. The conference was cosponsored by the U.S. National Science Foundation; the Soil Sci- ence Society of America; Decagon Devices, Inc.; UMS; and Campbell Scientific, Inc., and was held in partnership with the U.S. National Academy of Sciences. Funds supported the attendance of 15 students and postdocs from the United States. Co-conveners of the confer- ence were Harry Vereecken (Forschungszen- trum Jülich), Michael Young (University of Texas at Austin), Peter Troch (University of Arizona), and Paul Bertsch (University of Ken- tucky and the Commonwealth Scientific and Industrial Research Organisation (CSIRO)). We acknowledge the contribution of session conveners Matt Wallenstein, Claudia Boot, Nicolas Brüggemann, Dani Or, and Ciaran Harman and the lively and stimulating discussions of the attendees. We also acknowledge the excellent support staff at Biosphere II, who masterfully addressed all logistics during the conference.
