Environmental and vegetation controls on the spatial variability of CH(4) emission from wet-sedge and tussock tundra ecosystems in the Arctic

AIMS: Despite multiple studies investigating the environmental controls on CH(4) fluxes from arctic tundra ecosystems, the high spatial variability of CH(4) emissions is not fully understood. This makes the upscaling of CH(4) fluxes from plot to regional scale, particularly challenging. The goal of this study is to refine our knowledge of the spatial variability and controls on CH(4) emission from tundra ecosystems. METHODS: CH(4) fluxes were measured in four sites across a variety of wet-sedge and tussock tundra ecosystems in Alaska using chambers and a Los Gatos CO(2) and CH(4) gas analyser. RESULTS: All sites were found to be sources of CH(4), with northern sites (in Barrow) showing similar CH(4) emission rates to the southernmost site (ca. 300 km south, Ivotuk). Gross primary productivity (GPP), water level and soil temperature were the most important environmental controls on CH(4) emission. Greater vascular plant cover was linked with higher CH(4) emission, but this increased emission with increased vascular plant cover was much higher (86 %) in the drier sites, than the wettest sites (30 %), suggesting that transport and/or substrate availability were crucial limiting factors for CH(4) emission in these tundra ecosystems. CONCLUSIONS: Overall, this study provides an increased understanding of the fine scale spatial controls on CH(4) flux, in particular the key role that plant cover and GPP play in enhancing CH(4) emissions from tundra soils.