Geoscience Reference
In-Depth Information
Table 9.9
Infl uence of
permafrost on distribution of
soils in ice-free areas of
Antarctica
Area
(%)
Group
Area (km
2
)
With permafrost in upper 1-2 m
Orthels
21,639
43.7
Turbels
17,708
35.8
Histels
175
0.4
Non-Gelisols
7,903
16.0
Ornithogenic soils
254
0.5
Other
1,821
3.7
Total
49,500
100.0
9.6
Summary
Only 0.35 % of Antarctica is ice-free, amounting to an area of 49,500 km
2
. There
are three distinct climatic zones in Antarctica. The western Antarctic Peninsula and
the offshore islands (South Shetland and South Orkney Islands) have a subantarctic
maritime climate with comparatively mild temperatures and abundant precipitation,
including rainfall. Coastal East Antarctica has cooler temperatures and less precipi-
tation, all of which falls as snow. The inland mountains feature hyperarid and hyper-
gelic conditions. These climate differences are refl ected in active-layer thickness
and mean annual ground temperatures, which are greatest in maritime Antarctica
and least in the mountains. Birds, especially large penguin colonies, play an impor-
tant role in soil formation and in the ability of sites to become colonized by vegeta-
tion. Whereas soils in maritime and East Antarctica tend to be of Last Glacial
Maximum or Holocene in age, soils of inland mountains commonly range from
mid-Pleistocene to Miocene in age.
The climatic zonation is refl ected in the nature of the soils. The amounts of silt
and clay, organic C, total N, extractable P, and soil moisture and soil temperature
decline from the West Antarctic Peninsula to East Antarctica and then to the inland
mountains. Whereas soils of maritime and East Antarctica are often very strongly
acidic and low in base cations and soluble salts, soils of the inland mountains are
alkaline, strongly base saturated, and contain abundance salts.
The dominant soil-forming processes in maritime West Antarctica are soil
organic matter accumulation, acidifi cation, and hydromorphism, along with sul-
furization and phosphatization in some locations. These same processes occur in
coastal East Antarctica, along with a weak podzolization process. Desert pave-
ment formation, salinization, and rubifi cation are key processes in the inland
mountains.
Because the inland mountains comprise over 93 % of the ice-free area of
Antarctic, the predominant soil great groups are Anhyorthels, Haploturbels, and
Anhyturbels. Orthels, Turbels, and Histels comprise 44, 36 and 0.4 % of the soils of
Antarctica, with nongelisols accounting for 16 %.
