Chemical and biological properties, formation, occurrence and classification of Spodic Cryosols in a terrestrial ecosystem of East Antarctica (WilkesLand)
L. Beyer et M. Bolter, Chemical and biological properties, formation, occurrence and classification of Spodic Cryosols in a terrestrial ecosystem of East Antarctica (WilkesLand), CATENA, 39(2), 2000, pp. 95-119
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.