Life in a cold environment - Antarctica: Global Science from a Frozen Continent - page 194

Figure 6.20 Vegetation around a geothermal vent in the South Sandwich Islands. (Credit: Peter

Convey, BAS)

typically remain suf cient to allow year-round biological activity. In contrast,

along the Antarctic Peninsula and continent, biological activity is arrested by low
winter temperatures.
Antarctic soils are typically poorly developed, with low organic content, and
are heavily in uenced by disturbance and mixing during frequent cycles of freezing

and thawing (cryoturbation). Permafrost is not present in the sub-Antarctic at
least up to several hundred metres altitude but generally underlies ice-free ground
across the continent. Brown soils are reasonably well developed in the sub-Antarctic,
but are found only with larger stands of higher ( (flowering) plants in the maritime

Antarctic, and not at all on the main body of the continent. The presence of well-
developed moss communities has led to deep peat deposits in the sub-Antarctic,
dated to soon after the end of the Pleistocene glaciation. Such deposits are
unusual and younger in the maritime zone (up to 5 - 6000 years old), and are not

found in the continental Antarctic.
The apparent abundance and biomass of birds and seals on the sub-Antarctic
islands and parts of the continental coastline is deceptive, as these are a component