EXPLORING ECOSYSTEM METABOLISM AS A DRIVER OF COUPLED CARBON AND NITROGEN CYCLING AND CATCHMENT-SCALE BIOGEOCHEMICAL FLUXES (S)
Cycling of macronutrients like nitrogen (N) is inherently coupled to energy flow (C) through stream networks, with ecosystem metabolism as the coupling point between these two biogeochemical cycles. Despite their intrinsic linkage, the magnitude and stoichiometry of biological uptake of these two elements is rarely considered simultaneously or in the context of the ecosystem metabolic regime. We seek a new understanding of C/N dynamics to elucidate how ecosystem metabolism may couple C/N cycles, and how oligotrophic streams may be co-limited by both energy and macronutrients. We focus on 2 headwater stream networks where we performed single and dual nutrient TASCC additions across the snowmelt recession and baseflow hydrograph to estimate seasonal trends in C/N uptake kinetics. We assess how biological retention of C/N varies seasonally and in response to DOM gradients, and place these biologically-driven fluxes in the context of ecosystem metabolism and physically-driven C fluxes exported from the catchment. Our study explores the coupled nature of macronutrient and energy cycling in headwaters, and sheds lights on the important role biotic processes can play in mediating catchment scale biogeochemical fluxes.
Seybold, E. C., Duke University, USA, firstname.lastname@example.org
McGlynn, B. L., Duke University, USA, email@example.com
Location: Pojoaque/Nambe/Ohkay Owingeh
Presentation is given by student: Yes