Microbial Perspectives of the Methane Cycle in Siberian Permafrost Ecosystems

• Main Author: Wagner, Dirk
• Format: Conference Object
• Language: unknown
• Published: 2007
• Subjects: Global warming; lena delta; permafrost; Tundra
• Online Access: https://epic.awi.de/id/eprint/16784/; https://hdl.handle.net/10013/epic.26617

The Arctic plays a key role in Earths climate system as global warming is predicted to be most pronounced at high latitudes and because one third of the global carbon pool is stored in ecosystems of the northern latitudes. In order to improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosystems, the present study concentrates on investigations of microbial controls of methane fluxes, on the activity and structure of the involved microbial communities, and on their response to changing environmental conditions. For this purpose an integrated research strategy was applied, which connects trace gas flux measurements to soil ecological characterisation of permafrost habitats and molecular ecological analyses of microbial populations. Furthermore, methanogenic archaea isolated from Siberian permafrost have been used as potential keystone organisms for studying and assessing life under extreme living conditions.From 1998 to 2005, eight expeditions to the Lena Delta were carried out. Field work and sampling of different permafrost soils and sediments were mainly accomplished on Samoylov Island, central Lena Delta. In particular, the objectives of the study were: (1) to measure and balance methane fluxes from tundra environments, (2) to determine the soil ecological properties, (3) to gain more insights into the control functions of microorganisms, (4) to improve the knowledge of the abundance and biodiversity of microbial communities, and (5) to determine tolerance limits of methanogens under extreme living conditions.Long-term studies on methane fluxes were carried out since 1998. These studies revealed considerable seasonal and spatial variations of methane emissions for the different landscape units ranging from 0 to 362 mg m-2 d-1. For the overall balance of methane emissions from the entire delta, the first land cover classification based on Landsat images was performed and applied for an upscaling of the methane flux data sets. The regionally weighted mean daily ...