Climate Variability and Gas Fluxes in Agricultural Riparian Zones

Abstract:

Riparian zones are commonly used as best management practices (BMPs) in agricultural landscapes as tools to reduce NO₃ concentration in subsurface flow and pesticides/phosphorus/sediments in overland flow. However, as CO₂, N₂O and CH₄ concentrations continue to increase in our atmosphere, there is a need to better understand riparian zone contributions to greenhouse gases (GHG) emissions in agricultural landscapes. Currently, our understanding of GHG emissions at the soil-atmosphere interface in agricultural riparian zones excessively relies on wetland or near-saturated environment studies, or are simply estimates from edge of field conditions (e.g., IPCC guidelines for edge of field emissions). Further, the processes regulating CO₂, CH₄, and N₂O emissions are different, and therefore respond differently to environmental drivers. In this presentation, we discuss fundamental differences (or similarities) in GHG responses to seasonality and extreme hydrological events (storms, snowmelt, drought) across a range of riparian zones. Within this context, we also discuss the occurrence (or lack thereof) of hot moments of GHG emission: How often do they occur? What are the field-scale controls on hot moment occurrences, and how long do they last? Finally, we propose a new conceptual framework to generalize GHG emissions at the landscape scale beyond current wetland-based conceptual models.