Decomposition, nitrogen mobilization, nitrogen fixation and the importance of lakeside foams in fellfield soils of the Garwood Valley

Nitrogen, a necessary nutrient for plants and microbes, is frequently limiting in soils. Nitrogen fixation and decomposition, both ways plants and microbes obtain nitrogen, are very slow processes in Antarctica and probably not ecologically important. However, little work has been reported on this subject in Antarctica, and therefore this study's aim was to determine the extent of and factors and processes involved in fixation and decomposition of wet fellfield soil in the upper Garwood Valley. The biomass of algae (live and dead tissue) was determined in the fellfield soils between the Joyce and Garwood Glacier snouts. The metabolic weight loss of these tissues was experimentally determined and bacteria were isolated from the samples. The mobilization of nitrogen from an organic to an inorganic form and nitrogen fixation rates were studied. The ecological importance of foams which occur extensively on the lakesides and flushed soil surfaces was also investigated by culturing the microbes contained within.