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The Ecology of the Himalayas

Soil of the Himalayas

Flora

Fauna

Climate of the Himalayas

Title:Soil of the Himalayas
Credit:Compiled from multiple sources by Pragya
The soils found in the Himalayas are diverse in character depending upon altitude, vegetation cover, slope, structure and stage. The major soil groups in the Himalayas are brown hill soil, sub-mountain soils, mountain meadow soil and red loamy soils, apart from other less significant types. Most of the soils in this region are acidic in nature. Acidic soils are found in high altitude areas of the western Himalayas, at mid and high altitude regions of the central Himalayas and across all altitudinal ranges in the eastern Himalayas. The main types of soils are discussed below.
  • Himalayan foothill/terai soil: This type of soil is found in the sub-mountain and foothill tracts of the Himalayas ranging from the western regions in Jammu and Kashmir to the eastern most stretches in Arunachal Pradesh. While this soil type is extensively found in the foothills of Himachal Pradesh, it is only present in a narrow zone in Uttarakhand from Dehradun to Deori. This soil has a high content of organic matter and nitrogenous compounds, but lacks phosphate compounds. The soil is also found in the foothills of Darjeeling, where it has been transported by hilly rivers and streams at altitudes as high as 1500 m. Here, this soil is acidic and poor in plant nutrients and is made up of sandy material and raw humus.
  • Forest soil: This soil category is found across the Himalayas under coniferous and deciduous forests in the lower Siwalik range. This soil type is formed either under conditions of high acidic content (where there is acidic humus) or under mildly acidic conditions. The top soil of the soil profile is very rich in humic matter formed by twigs, bark, leaves and needles. An important variety of forest soil is brown forest soil, which occurs under dense deciduous forests. Organic debris from the dense canopy contributes to the topsoil in the form of a thick layer of humus. This soil can be classified into mildly acidic with high base content and acidic with low base content.
  • Podzols: Podzols are found in the western Himalayas and in few areas in Nepal, Sikkim and Arunachal Pradesh. They are a class of infertile acidic soils that develop under coniferous forests in humid temperate conditions, where the rate of precipitation exceeds the rate of evaporation. A continuous percolation of water causes leaching of minerals like iron and alumina from upper layers, resulting in the formation of a grey bleached zone on the upper surface. This makes the layer look like ash, giving the underlying soil its name: podzol (pod=under, zola=ash in Russian). The lack of nutrients and acidic nature of podzols make them poor agricultural soils. The percolated minerals often form an impermeable layer at the lower end of the soil profile, which restricts water drainage. These soils occur in high altitude areas near snowline areas. The parent rock over which it develops varies from quartzite to granite, schist and gneissic rocks. The depth of the soil ranges from a few centimeters to a meter. However, sesquioxides or iron oxides usually found in podzols are generally absent in the podzolic soils of the Himalayas. Podzols found in the Himalayas can be divided into two groups: iron podzols (common in Garhwal-Kumaon) and humic podzols.
  • Red and black soils: These soils are found in isolated areas in Nepal, Bhutan, Uttarakhand (Garhwal region) and Himachal Pradesh. These are formed from acid and basic igneous rocks like granite and basalt. They are further grouped into red soil dominant type, which is lime deficient, carbonate free and light textured and black soil dominant type which is comparatively less clayey and deficient in lime. Red and black soils are deficient in nutrients like phosphate, nitrogen, lime and humus. Their depths vary from 1-70 cm and may be light to dark brown in colour. These soils support coniferous and mixed deciduous forests of Pinus and Quercus species as well as scrublands.
  • Desert (arid) soils: These soils are found in the cold desert areas of Ladakh (Jammu and Kashmir), Lahaul, Spiti, Kinnaur and Bharmour (Himachal Pradesh) and pockets of northern Uttaranchal and Sikkim. These regions have a unique physical, biological, hydrological and anthropological setting that is markedly different from that of the adjoining regions. These soils are sandy to loamy in texture with clay content of less than 15%. Desert soils are pale brown to yellowish brown in colour and are infertile, lacking nutrients like nitrogen, phosphorous, potassium, sulfur and zinc.
  • Mountain and hill soils: It is a collective name given to a number of soil types occurring at very high altitude areas under sub-tropical and temperate conditions under a wide variety of forests. These soils have been termed as dabar soils in some parts of Garhwal-Kumaon. Mountain and hill soils are very thin, fertile and may be less than a centimeter deep on steep slopes. These may occur at elevations above 2750 m in the western Himalayas, over 2500 m in Nepal and over 2400 m in the eastern Himalayas. These soils are mixed with pebbles and gravel in many regions. The texture varies from sandy to sandy loam. The soil reaction varies from acidic to neutral and the organic matter content of these soils ranges from 1 to 5 percent.
  • High altitude meadow soil: This soil type is found in high altitude meadows found near the snowline in all parts of the higher and trans Himalayas. Negligible rainfall occurs in these areas and the main form of precipitation is snow. The soil found here is very thin and fragile. Since the texture of the soil is very coarse with high gravel content, they are prone to displacement due to slides and avalanches. These soils are dark in colour and have a high content of humus.
Apart from the above-mentioned soils, traces of alluvial soil are found in parts of Uttarakhand and lateritic soils are found in some parts of Arunachal Pradesh. Erosion due to wind and water is a common problem in the Himalayan belt, especially on steep slopes. In recent times, several anthropogenic factors like indiscriminate grazing and deforestation has negatively affected the quality of Himalayan soils.
Contents:
Himalayan foothill/terai soil
Forest soil
Podzols
Red and black soils
Desert (arid) soils
Mountain and hill soils
High altitude meadow soil