Fundamentals of the soil science. Arctic Soils

Размещено на http://allbest.ru

Fundamentals of the soil science. Arctic Soils

1.Scope, area, geographical spread

soil island arctic

Arctic soils common islands in the Arctic latitudes. They formed in cold dry climate and permafrost in poor vegetation. The humus content in them very little.

Within the polar zone highlighted two areas: the North American and Eurasian. Each region is divided into two soil zones - arctic and subarctic (tundra).

Arctic desert zone limited 5 ° C isotherm of the warmest month. It occupies the southern part of the Canadian Archipelago, Greenland (except southern regions), the island of Svalbard, an archipelago Franz Josef Land and Severnaya Zemlya.

Total area - 7.16 million hectares.

Pic (1). Arctic

The conditions of soil formation (parent material, climate, relief ).

Arctic climate zone is very harsh, cold and dry. During the year falls here 150-300 mm rainfall, usually in the form of snow. Snow cover is low, but on the improvement does not. The average annual temperature is -10-14 ° C, the average temperature in the winter months - 25-31 ° C, and the warmest summer - +8-9 ° C. Duration of the frost-free period only 12-14 days. The entire area of ??common permafrost, which is the dominant factor in soil formation. Thaw loamy soil to a depth of thirty-40 cm, sand - by 75-100 cm permafrost slows all geochemical and microbiological processes. In these conditions prevail frosty physical weathering, thus forming cover gravelly small-earth. For the water regime of arctic soil moisture characteristic contrast throughout the year. Spring melt water stagnate on the frozen horizon and re-moisturize soil. In summer, under the influence of clock insolation and high winds and dry soil cracks.

Processes of soil formation: kriohenez - soil under the influence of permafrost (mainly physical weathering of minerals, clays neosynthesis absent, accumulation of water-soluble compounds). There - the accumulation of iron, due to its cryogenic pulling in seasonal changes AFP.

Arctic soils are formed in the foothills and marine terraces. The main bedrock is gravelly and stony rocks that blocked loose Quaternary sediments of marine and water-glacial origin. Most of them are sandy or easily-loam composition.

Capacity of arctic soil profile determined by the depth of seasonal thawing and averages 40 cm soils are fragmentary. Profile poorly differentiated, skeletal:

But - moss or lichen litter;

H - humus, brown-brown, granular, fractured, capacity 4-10 cm;

HP - brown, boulderily, fractured, lumpy, capacity of 35-45 cm, often - thixotropic;

P - parent rock fragments brownish color.

Relief: dominated by glacial abrasive and accumulative forms, marine terraces (hollow, circuses, hilly moraine formation, etc.). Microrelief polygon.

Typical topography in the area is moraine hills, mutton foreheads, fjords polygonal soils, and in the mountains - circuses penalty troughs.

Vegetation zone consists mainly of mosses and lichens. Plants settle in clumps and hollows along the cracks between polygons. Come across here as fungi, algae, and several species of flowering. The degree of coverage of the soil does not exceed 25%. Annual growth of biomass is 2,7-7,0 kg / ha.

2.Properties and structure

Soil cover arctic zone - a complex arctic soils, stains and arctic soils under vegetation. Due to the shallow thawing Arctic soils have a short profile.

Sub arctic typical soils common in the southern part of the zone under moss-differently-May-grass vegetation, which is confined to frost cracks. This subtype has the following structure.

O Horizon - moss-lichen pillow 2-3 cm

Horizon A - humus, brown-brown, power up to 10cm, structure small-clotted or granular, fractured, compacted, loam texture.

Horizon B - transitional, light brown, dark brown down, power 35-45 cm, dense, fractured, loam.

Horizon C - bedrock permafrost, with lenses and crystals of ice.

Sub-Arctic desert soils common in northern areas in equal parts of islands under moss-lichen clumps. Capacity of arctic soil profile determined by the depth of seasonal thawing and averages 40 cm surface arctic desert broken vertical grid frost cracks in polygonal form size 10-20cm. On their surface a salt crust.

In soils of this subtype isolated following horizons:

A - Humus, capacity up to 4 inches, dark-brown, easily-loam, fragile granular structure contains many plant residues.

B - transitional, power up to 30-40 cm, light brown, sandy loam, structureless.

C - bedrock, sandy, frozen mass.

3.Level of fertility

soil island arctic

Arctic soils contain little humus (1-2%, sometimes up to 6%), the reaction of the soil solution acidulated or neutral (pH = 6,0-6,5), the amount eaten cations does not exceed 12-15 mg per 100 g soil degree of base saturation 96-99%. As part of the organic matter is dominated by fulvic acids. The ratio of Cr: Sf = 0.4-0.5. In many areas soils mobile forms of iron. In the upper part there is little accumulation of Fe2O3 silt dominated sand fraction.

There are two subtypes of arctic soils: desert and typical humus. Desert arctic soils distributed in the northern zone under very sparse vegetation, often with salt and algal crust, neutral or slightly alkaline medium humus discrete, capacity of about 4 cm

Typical arctic humus soils are much more powerful humus horizon, higher humus content, lack of salt accumulation weakly acidic environment.

Skeletal soils, ohleyennya absent due to low rainfall and light parent rock, fracturing and schebenyuvatistyu. Arctic soils in agriculture are not used, but they can organize hunting grounds and reserves.

Ohleyennya profile arctic soils weakly expressed. A small amount of precipitation, chadility bedrock and draining role cracks cause aerobic process of soil formation.

Primitive soil-spots are formed on the central part of the grounds, which are covered with blue-green algae. Lichens and higher plants in these soils there.

In lower areas of relief from stagnant waters under moss-grass marsh vegetation formed arctic soils include a clay and nonclay.

In low-lying shores of islands that flooded at high tide, forming Marching saline soils. In the upper horizon they contain about 1% water-soluble salts.

4.The use and protection

Arctic soils are unsuitable for use in agriculture. However, they can be used for organizing hunting grounds and reserves in order to maintain and increase the number of rare species of animals (polar bear, musk oxen, birds, etc.).

Размещено на Allbest.ru