Wetlands in a changing world: processes, feedbacks and the climate benefits of wetlands

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Among the numerous ecosystem services provided by wetlands, from wildlife habitat to water quality improvement, climate regulation is identified as one of their most important benefits to society. Wetland ecosystems play an important role in the global carbon (C) cycle; they provide the ideal environment for C sequestration and long-term storage of atmospheric carbon dioxide (CO2), yet they are also the largest single source of atmospheric methane (CH4), a much more potent greenhouse gas (GHG) than CO2 in the short term. Climate change has the potential to increase GHG emissions from wetlands, however, the consequences of rising temperatures on wetland GHG dynamics and C cycling remains uncertain. Furthermore, preventing further wetland loss and restoring wetland ecosystems has been identified as important in limiting future emissions to help meet climate goals. While wetlands have the potential to both amplify and attenuate global warming, wetland responses to climate and land-use change are still poorly understood. This research program aims to address this knowledge gap by providing an improved mechanistic understanding of the response of wetland C and GHG dynamics to climate variability and management. Over the next five years, we will investigate land-atmosphere interactions across three distinct natural and managed wetland ecosystems to quantify and compare annual GHG and C budgets, identify key controls on trace gas fluxes, and improve predictions of wetland C fluxes. The four short-term objectives of this research program are addressed through linked research activities that combine field-based measurements, remote sensing, and modeling to provide novel insights into the controls and timing of wetland C and GHG fluxes across a range of spatial and temporal scales. The core of this research program will be new and ongoing eddy covariance measurements of ecosystem-scale CO2, CH4, water and energy fluxes at the three wetland sites. These sites include a natural and restored bog in the Burns Bog Ecological Conservancy Area, BC, and a tidal marsh in the Boundary Bay Wildlife Management Area, BC. By conducting year-round measurements of trace gas fluxes across the sites, we will quantify annual C and GHG budgets across these wetland ecosystems to assess and compare their net warming or cooling effect on climate. We will also investigate the dominant controls on wetland GHG exchange across hourly to interannual time scales, explore how drivers vary across wetland types and between natural and restored sites, and characterize within-site spatial variability in trace gas fluxes. We will also link remote-sensing indices to flux tower measurements to model and upscale C fluxes in restored and natural wetlands. This research is critical to better predicting current and future contributions of wetlands to climate change, which is highly relevant for policies aiming to limit the level of global temperature rise.