THE MAJOR BIOCLIMATIC ZONES: THE FRIGID ZONE AND MOUNTAINS

THE FRIGID ZONE.

 

Geographical distribution.

Location: between the polar circles and the poles.

Characteristics: harsh cold, limited light and low precipitation levels.

We can distinguish two different zones: 

• the glacial environment (ice caps), located between the 75th parallel and the poles. In the North, Greenland and in the south Antarctica.
• the periglaciar environment or the edges of the polar regions (tundra). Includes the far northern regions of North America, Europe an Asia and in the southern hemisphere the far southern regions of Argentine and Chile.

The polar climate: dominant cold.

Main characteristics:

• Low temperatures all year around (never above 10ºC). We have to distinguish between the:

1. Ice caps, always bellow zero degrees.
2. Tundra, during the summer temperatures rise above 0ºC.

• Scarce precipitations, generally as snow.

1.  Ice caps, almost no precipitation.
2. Tundra, below 250-300 mm per year.

• Most of water apperars in solid form (ice). There are differences:

1. Ice caps, only ice.
2. Tundra, liquid water during the sumer. Large acumulations of ice on the permantly frozen subsoil (permafrost).

Marie Byrd Land, Antarctica.

Permafrost, Tundra.

Polar vegetation.

In the polar caps there is no vegetation.

In the tundra, vegetation is adapted to the very harsh conditions:

1. little light.
2. low temperature.
3. strong winds
4. poor soils.

We are goint to find:

1. low-lying plants, such as mosses (in spanish, musgo) and lichens (in spanish, liquen).
2. Shrubs, such as dwarf willows.

Mosses, Tundra

Dwarf willows

MOUNTAIN BIOCLIMATE.

Location.

Mountain bioclimate is azonal, it can be found at any latitude.
We can distinguish two zones:

• low mountain 
• high mountain or alpine. Here average temperature does not rise above 10ºC and there are no trees.

Characteristics:

High altitude determine the climatic elements:

• Low temperatures: temperature drops 0.6ºC for every 100 metres above sea level.
• High precipitacion levels until you reach 1.000 to 2.000 metres. Then starts to decrease.
• Rivers are irregular

In the temperate zone we have to distinguish between two aspects (aspect: direction that a topographic slope faces):

• sunlit aspect (in spanish, solana), faces the Sun directly: higher temperatures with greater daytime and thermal contrasts.
• shaded aspect (in spanish, umbría): lower temperatures, lower thermal contrasts.

 

Mountain vegetation.

Vegetation has to adapt to harsh conditions.
We can distinguish several altitudinal zones according to the distance from the base of the mountains:

• Woodlands. We have to distinguish between:

1. Equatorial rainforest and tropical woodland in the torrid zone.
2. Deciduous woodland (oak trees and beeches) and coniferous woodland (pine and fir trees).

Deciduous Woodland. Alps.

Source: By Gabriel HM - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=50473707

Tropical Woodland, Himalaya (2.000 m).

Source:

https://www.flickr.com/photos/38019504@N04/6271593046/

• Scrubland and pastures.
• Moos and lichens.

External links:

http://earthobservatory.nasa.gov/Experiments/Biome/biotundra.php