Methan-e-scape

Methane is a powerful and short-lived greenhouse gas that is responsible for about a fifth of the current global warming. Understanding the sources and emission pathways of this greenhouse gas and its possible future development is an important part of climate modeling and mitigation. Freshwater ecosystems are responsible for almost half of the world`s methane emissions into the atmosphere. However, current estimates are very uncertain due to the high spatial and temporal variability of methane emissions from streams and rivers and the poor accounting of methane ebullition to emission estimates. In this process, methane literally bubbles out of the system and into the atmosphere. The factors responsible for methane emissions in rivers and streams, and ebullition in particular, are likely to be very complex, making predictions and modeling of global carbon budgets and future climate difficult. Therefore, there is an urgent need to better consider the patterns of methane emissions from rivers in order to get a more complete understanding of the global methane cycle. The project aims to decipher the magnitude and drivers of methane ebullition and its production in sediments in streams. Furthermore, we will assess how much methane escapes from streams and other aquatic ecosystems in a floodplain forest ecosystem to reveal the functional role of aquatic ecosystems in a landscape. These are the main aims of a collaborative project led by aquatic ecologists from WasserCluster Lunz and the University of Vienna in Austria and aquatic and terrestrial ecologists from the Global Change Research Institute in Brno, Czech Republic. The research program will investigate environmental and microbiological drivers of methane ebullition and production in the field and laboratory experiments. Four sampling campaigns over an annual cycle in six streams (three in Czech Republic and three in Austria) will be conducted. In the second year, laboratory incubations will be set-up to study environmental drivers of methane production under controlled conditions. The challenge of the role of aquatic ecosystems in landscape methane emissions will be tackled by field measurements of methane fluxes from various components (soil, trees, lakes, streams) of a floodplain forest ecosystem. In combination with eddy covariance data, an atmospheric measurement technique to measure and calculate vertical turbulent fluxes, we will quantify the contribution of aquatic versus terrestrial habitats to overall landscape methane fluxes. The results from this project will improve our knowledge of the drivers of processes related to methane dynamics in streams and will advance current concepts and help to understand the impact of projected environmental and climatic changes on atmospheric methane.