Chemical and biological properties, formation, occurrence and classification of Spodic Cryosols in a terrestrial ecosystem of East Antarctica (WilkesLand)

Soils with the morphological features of podzols are widespread in coastal East Antarctica. Neither the World Reference Base of Soil Resources (WRB) n or Soil Taxonomy (ST) adequately classify these soils, so we recommend the addition of Spodic Cryosol at the second hierarchical level in WRB and Spod orthel at the great group level of ST. We divide the Spodic Cryosols into o rnithogenic and non-ornithogenic Spodic Cryosols based on inorganic chemist ry, soil organic matter composition and microbiology. The occurrence of Spo dic Cryosols depends on parent materials, soil texture, surface pattern, so lar energy input and vegetation patterns. Antarctic Spodic Cryosols form on solid rocks, outwash sediments and abandoned penguin rookeries, and repres ent 20% of the soil-landscape of Wilkes Land, with one-third ornithogenic a nd two-thirds non-ornithogenic. Ornithogenic Spodic Cryosols are related to tectonically uplifted abandoned penguin rookeries. All Spodic Cryosols contain large amounts of carbon and nitrogen. During pe dogenesis iron complexed with organic matter in the topsoils has been alter ed to oxides and crystalline iron minerals, but aluminium remains almost en tirely 100% organically bound throughout the profile. Meltwater and a moss cover are essential for podzolization on the non-ornithogenic sites, and at the ornithogenic sites, the chemically aggressive solution from dissolved guano has bleached the uppermost AE horizon and translocated iron and alumi nium into the subsoil. The low salinity suggests that downward leaching exc eeds upward transport by evaporation. Intensity of podzolization is determi ned by microclimate, soil microbial effects and parent materials. The perma frost table may cause precipitation of organic matter in the subsoil. Mg an d P levels are high. The P level is very high in the ornithogenic soils. K, P, pH, base saturation (BS) and bacterial colonization reflect the influen ce of guano. In the AE horizon of ornithogenic soils colonization by lichen s and/or mosses depresses bacterial activity. The mean C/N ratio of approxi mately 11 and the abundance of carboxylic carbon compounds probably derive from organic acids and oxidized carbohydrates. Migration of organic acids, non-humified carbohydrates and N-containing compounds is suggested as the m ain mechanism of podzolization. (C) 2000 Elsevier Science B.V. All rights r eserved.