Life on land: Non-aquatic ecosystems

Abstract

Water availability is of primary importance in controlling the abundance of life in non-aquatic habitats (Kennedy 1993). Unlike aquatic habitats, there is no free-standing water but water may be found in the minute spaces between particles of rocks, soils and snow. Its supply decreases with progression from relatively warm and moist maritime Antarctica to colder continental Antarctica where conditions are often extremely dry. For example, in maritime Antarctica, green expanses of moss can cover more than a hectare of ground, and lichens thickly encrust surrounding rocky slopes, whereas in the McMurdo Dry Valleys no vegetation is immediately apparent and brown rock and soil surfaces dominate the landscape. Also important is the microclimate at ground level. In summer, solar heating of dark vegetation, rocks and soils stimulates growth and activity of organisms, and may also increase water supply by melting overlying and adjacent ice and snow. This chapter first discusses life found on and in soils and rocks in typical ice-free areas, in conditions progressing from the most favourable to the most severe. It then considers unusual habitats provided by soils warmed with heat from volcanoes, by snow and ice and by extensive wetlands thought to be present under the Antarctic ice sheets.