Properties, formation, and geo-ecological significance of organic soils in the coastal region of East Antarctica (Wilkes Land)

The ice-free antarctic vegetation oases are characterized by specific soil patterns. Four organic soils from mosses in Wilkes Land close to the Australian Casey Station (latitude: 66°18′S, longitude: 110°32′E) are discussed with respect to soil formation, ecology, and distribution. A soil survey of the ice-free coastal landscape suggests that mosses are the main source of organic soils. The soil organic matter transformation pathways differ greatly despite the fact that carbon sources are mostly the same moss species. Humification rate is probably controlled by microclimatic and soil moisture regimes as well as by the microbial colonization, which influences the nitrogen dynamics. The soils are affected by mineral particle inputs from seabird influenced ice- and vegetation-free surfaces. Carbon-14 dating, carbon-13/carbon-12 isotopic ratios and detailed SOM investigations are recommended for future studies to improve our current understanding of SOM origin, accumulation, and transformation. The Von Post humification scale is not an adequate indicator for estimating humification in antarctic organic soils. Even small areas or percentages of organic soils strongly affect the carbon and nitrogen stocks at landscape scales.