POLAR DESERTS: CHARACTERISTICS, CLIMATE, FLORA AND FAUNA - GEOGRAPHY - 2025

The polar deserts are considered among the most extreme environments, they include some of the cold dry habitats of the planet. They are defined as being the northern (Arctic area) and southern (Antarctic area) polar ice caps of the Earth.

These areas have annual rainfall less than 250 mm and maximum temperatures below 10 ^° C. Desert is defined as a biome -bioclimatic area- in which there is very little rainfall and few forms of life.

Figure 1. Landscape of polar deserts (Arctic). Source: No machine-readable author provided. Michael Haferkamp assumed (based on copyright claims)., via Wikimedia Commons Despite these harsh conditions of drought, low temperatures and little solar radiation, there is a whole spectrum of microorganisms, non-vascular plants and animals that manage to adapt and develop in these polar regions.

These elements include mosses, lichens, algae, microscopic invertebrates such as nematode worms, tardigrades and microarthropods (all less than 1mm in size), fish, birds and mammals, with little diversity but significant populations.

General characteristics

Weather

Temperature

Although very similar, the climate of the Antarctic polar helmet is more extreme than that of the Arctic. Antarctica has an average summer temperature of -10 ° C; in winter the minimum drops to -83 ° C, and even at lower temperatures.

In the Arctic region the winter temperature reaches up to -45 ° C or -68 ° C. During the summer the average temperature is 0 ° C.

Precipitation

Both in Antarctica and in the Arctic there is a low rate of precipitation in the form of snow, in a range of 3 mm per year of liquid water equivalent in the inner continental areas and about 50 mm per year of liquid water equivalent in areas close to the coasts.

Most of the time water in a liquid state is not biologically available and the low humidity conditions in the air favor the evaporation of any rainwater and sublimation (passage from solid to gas) of snow.

Winds

Other climatic characteristics are strong winds of up to 97 km / h and very low relative humidity.

Solar irradiation

Solar radiation strikes obliquely, steeply with respect to the surface and uninterruptedly for six months (spring and summer) of "polar day". The other six months of the year (autumn and winter) are of total darkness and cause the so-called "polar night".

Floors

The soils are usually infertile, formed by granites, sandstones, dolerites or black granite. These soils present alternation of freezing and thawing, they are of high salinity, pH between neutral and alkaline and with very little organic matter. The ground may be frozen, which is often called permafrost.

Topography

It is dominated by glaciers, rocks, boulders, rock fragments, snow dunes, lakes covered in a perennial way by ice and very low flow, scarce and ephemeral streams of water.

Flora

The vegetation is sparse and generally dominated by cryptogams (plants that do not reproduce using seeds, such as mosses, liverworts, and lichens).

Coverage is poor (2%). This type of vegetation is particularly developed in Antarctica.

The diversity of flowering plants in the Arctic is much higher than in Antarctica, where there are only 2 species of phanerogams.

In the Arctic region there are extensive and dense covers, which in some areas are enriched with nutrients - such as the parts that are under the cliffs and rocks where birds nest. This vegetation has no equivalent in Antarctica.

In the Arctic region there is a tundra zone and includes habitats dominated by small vascular plants, without significant growth of trees or grasses, except for the prostrate dwarf forms, such as the Arctic willow (Salix arctica), which is supported by permafrost.

In Antarctica there are herbs up to 2 m and mega herbs such as Stilbocarpa polaris and Pringlea antiscorbutica.

Arctic flora

In the Arctic region there are creeping dwarf shrubs such as the polar willow (Salix polaris), one of the smallest willows in the world that only reaches 2 to 9 cm in height. Also present are the arctic willow (Salix arctica), the miniature willow (Salix herbacea, grass 1 to 6 cm tall) and the shrub Salix lanata.

Figure 2. Polar willow (Salix polaris). Source: Victor M. Vicente Selvas, from Wikimedia Commons There are several species of the genus Saxifraga: Saxifraga flagellaris, a small plant of 8 to 10 cm in size, endemic to the Arctic; Saxifraga bryoides, a very low-growing species that exceptionally exceeds 2.5 cm in height; Saxifraga cernua, small shrub 10 to 20 cm in size; and another small shrub Saxifraga cespitose.

The dwarf birch (Betula nana), a 1 m tall shrub, are also described; the small shrub Dryas octopetala; Micranthes hieracifolia, small phanerogam 10-20 cm tall; and the dwarf species Polemonium boreale.

Likewise, it presents the following herbs: Astragalus norvergicus, 40 cm high; Draba lactea, which grows between 6 and 15 cm; Oxyria digyna, 10 to 20 cm in size; the arctic poppy Papaver radicatum; Arctic sweet coltsfoot Petasites frigidus, 10-20 cm tall; and the Potentilla chamissonis, which reaches between 10 to 25 cm in height, among others.

Flora

In Antarctica, the scene of more extreme conditions, the vegetation is much smaller, due to the very low temperatures and the long periods without light, of total darkness.

Among the approximately 100 species of mosses reported, the endemic mosses Schistidium antarctici, Grimmia antarctici and Sarconeurum glaciale stand out.

75 species of fungi have been reported to develop in Antarctica; of these there are 10 macroscopic species that grow sporadically alongside mosses in the summer. There are also 25 species of liverworts, such as the alga Prasolia crispa, among other 700 green and blue-green algae.

Vascular plants

Among the woody plants there are a few conifers belonging to the Podocarpaceae and Araucariaceae families; these are species of the Cunoniaceae and Atherospermataceae families. The southern beech trees (Nothofagus antarctica) also stand out.

There are two endemic or native Antarctic phanerogamic vascular species: a grass, Antarctic grass, Antarctic hair grass or Antarctic hair grass (Deschampsia antartica); and the Antarctic pearl, Antarctic carnation or pearl grass (Colobanthus quitensis), with small white flowers. These are small and grow among the mosses.

Figure 3. Antarctic pearl grass (Colonbathus quitensis). Source: Antarctic_Pearlwort.jpg: Liam Quinnderivative work: Bff, via Wikimedia Commons

Fauna

Invertebrates

The invertebrate fauna of the soil of the two terrestrial polar zones is distributed in patches. Includes protozoa, tardigrades, rotifers, nematodes, worms, mites, and collembola.

The Antarctic is home to a much smaller diversity of insects than just two species of flies, while the Arctic has a variety of flies and beetles. Spiders also exist in the Arctic.

Most polar insects are not herbivores; They feed on microorganisms and detritus (decomposing organic matter).

Vertebrates

The presence of herbivorous vertebrates in the Arctic is a very important distinguishing factor between the two polar regions.

In the Arctic there are herbivores such as the small rodent or arctic lemming (Dicrostonix torquatus) and the arctic hare (Lepus arctica), as well as larger species such as reindeer (Rangifer tarandus) and musk oxen (Ovibus moschatus).

Large populations of migratory birds - such as snow geese (Chen caerulescens), ptarmigan (Lagopus muta), snow bunting (Plectrophenax nivalis), and Arctic gulls (Sterna paradisaea) - use the upper Arctic during the warm season to feed.

Figure 4. The arctic fox with summer fur (in winter they turn white), one of the most beautiful and well-adapted animals in this area. Source: Claudia.Garad, from Wikimedia Commons Hunter vertebrates - such as the polar bear (Ursus maritimus) and the Arctic wolf (Canis lupus arctos) - are present throughout the year in the Arctic region. The musk ox is the largest herbivore, with good coverage of insulating coat from the cold.

On the other hand, a particular factor in coastal Antarctic ecosystems is the concentration of seabirds and mammals in the reproductive, rearing or resting stages. The transfer of nutrients from these animal concentrations can fertilize and accelerate the development of vegetation and associated arthropod communities.

The fauna of the polar regions has adaptation mechanisms like those of mammals that develop dense coats and accumulate fat in the subcutaneous zone. Others live sheltered from the cold in galleries and underground tunnels, and some migrate during the months of lower temperatures.

Arctic fauna

Land mammals

The Arctic is home to polar bears (Ursus maritimus), arctic wolves (Canis lupus arctos), arctic foxes (Vulpes lagopus), musk ox (Ovibos moschatus), caribou or reindeer (Rangifer tarandus), arctic hare (Lepus articus) and the arctic lemming (Dicrostonix torquatus).

Figure 5. Polar bear (Ursus maritimus), whose white fur serves as camouflage in the snowy landscape to protect itself and to go unnoticed when preparing to hunt. Source: Alan Wilson, via Wikimedia Commons

Marine fauna

Among the Arctic marine fauna there are fish, mollusks and mammals such as baleen whales (Mysticeti spp.), Belugas (Delphinapterus leucas), seals (Phocidae family) and walruses (Odobenus rosmarus).

Herbivorous primary consumers are the arctic hare, musk ox, and caribou. The secondary consumers that prey on these herbivores are the arctic wolf and the fox. The polar bear is a predator of seals and fish.

Birds

In the Arctic there are few birds, and these are migratory, such as the Arctic tern or Arctic tern (Sterna paradisaea) -which migrates between the Arctic and Antarctica- and the snowy owl (Bubo candiacus).

Fauna of Antarctica

The fauna of Antarctica is characterized by the low number of species (little diversity), but by a great richness in individuals. There are no terrestrial mammals or walruses like in the Arctic, nor amphibians or reptiles, but the marine fauna is the most abundant and varied on the continent.

Penguins

Antarctic penguins of 5 species live in Antarctica. These include the emperor penguin (Aptenodytes forsteri) and the adelia penguin (Pygoscelis adeliae). Both permanently inhabit this area.

There are also three migratory species: the gentoo penguin (Pygoscelis papua), the king penguin (Aptenodytes patagonicus), and the chinstrap penguin (Pygoscelis antartica), which travel to less adverse climates during the winter.

Figure 6. Emperor penguin (Aptenodytes forsteri). Source: Hannes Grobe / AWI, from Wikimedia Commons

Flying birds

The other birds of Antarctica are flying, such as the traveling or wandering albatross (Diomedea exulans), the polar skua (Catharacta maccormiki), the Antarctic cormorant (Phalacrocorax bransfieldensis), the Dominican or kitchen gull (Larus dominicanus) and the brown gull or skúa (Catharacta skua).

There are also petrels such as the checkerboard or cape pigeon (Daption capense), which has black and white plumage; and the Antarctic giant petrel (Macronectes giganteus). The Antarctic pigeon (Chionis alba) lives permanently in Antarctica.

Fish and crustaceans

Marine aquatic fauna is made up of some fish such as Antarctic cod (Notothenia corliceps and Dissostichus mawsoni) and toothfish (Dissostichus eleginoides), krill crustaceans (Euphasia superba), seals and whales.

Seals

Several species of seals exist in Antarctica: the Ross seal (Ommatophoca rossi), the Weddell seal (Leptonychotes weddellii), the southern elephant seal (Mirounga leonina), the crabeater seal (Lobodon carcinophagus), the Antarctic fur seal (Arctocephalus gazella) and the sea leopard or leopard seal (Hydrurga leptonyx).

Whales

Among the species of whales that live in Antarctica are the blue whale (Balaenoptera musculus), the fin whale or fin whale (Balaenoptera physalus), the Antarctic fin whale (Balaenoptera borealis) and the minke whale (Balaenoptera bonaerensis).

Also noteworthy are the humpback whale (Megaptera novaeangliae), the southern whale (Eubalaena glacialis) and the toothed whales: sperm whale (Physeter macrocephalus, Physeter catodon), the orca (Orcinus orca) and the bottlenose whale or southern pilot whale (Hyperodon planifio).).

References

1. Ball, A. and Levy, J. (2015). The role of water tracks in altering biotic and abiotic soil properties and processes in a polar desert in Antarctica. Journal of Geophysical Research: Biogeosciences. 120 (2): 270-279. doi: 10.1002 / 2014JG002856
2. Goordial, J., Davila, A., Greer, C., Cannam, R., DiRuggiero, J., McKay, C., and Whyte, L. (2017). Comparative activity and functional ecology of permafrost soils and lithic niches in a hyper-arid polar desert. Environmental Microbiology. 19 (2): 443-458. doi: 10.1111 / 1462-2920.13353
3. Hoffmann, MH, Gebauer, S. and von Rozycki, T. (2017). Assembly of the Arctic flora: Highly parallel and recurrent patterns in sedges (Carex). American Journal of Botany. 104 (9): 1334-1343. doi: 10.3732 / ajb.1700133
4. Johnston, V., Syroechkovskiy, E., Crockford, N., Lanctot, RB, Millington, S., Clay, R., Donaldson, G., Ekker, M., Gilchrist, G., Black, A. and Crawford, JB (2015). Artic migratory birds initiative. AMBI. Ministerial meeting in Iqualuit, Canada, April 24-25 2015.
5. Nielsen, UN, Wall, DH, Adams, BJ, Virginia, RA, Ball, BA, Gooseff, MN and McKnight, DM (2012). The ecology of pulse events: insights from an extreme climatic event in a polar desert ecosystem. Ecosphere. 3 (2): 1-15. doi: 10.1890 / ES11-00325
6. Rosove, MH (2018). Who discovered the emperor penguin? A historical survey from James Cook to Robert F. Scott. Polar Record. 54 (1): 43-52.