Major Soil Types of India: Alluvial Soils & Black Soil

Table of Contents

• Major Soil Types of India
• Alluvial Soils
  • Characteristics of Alluvial Soils
  • Chemical properties of Alluvial Soils
  • Distribution of Alluvial Soils in India
  • Crops in Alluvial Soils
  • Geological divisions of alluvial soils
    • Bhabar
    • Terai
    • Bhangar
    • Khadar
• Black Soils
  • Characteristics of Black Soils
  • Colour of Black Soils
  • Chemical Composition of Black Soils
  • Distribution of Black Soils
  • Crops in Black SoilsShareWhatsAppTweetEmail

Soil Types of India – Alluvial Soils – Black Soils – Characteristics, Chemical properties, Distribution, Divisions: Bhabar, Terai, Bhangar, Khadar.

Major Soil Types of India

• Geologically, Indian soils can broadly be divided into soils of peninsular India and soils of extra-peninsular India.
• The soils of Peninsular India are formed by the decomposition of rocks in situ, i.e. directly from the underlying rocks.
• Soils of Peninsular India are transported and re-deposited to a limited extent and are known as sedentary soils.
• The soils of the Extra-Peninsula are formed due to the depositional work of rivers and wind. They are very deep. They are often referred to as transported or azonal soils.

Major groups:

• Alluvial soils,
• Black soils,
• Red soils,
• Laterite and Lateritic soils,
• Forest and Mountain soils,
• Arid and Desert soils,
• Saline and Alkaline soils and
• Peaty and Marshy soils.

Alluvial Soils

• Alluvial soils are formed mainly due to silt deposited by Indo-Gangetic-Brahmaputra rivers. In coastal regions some alluvial deposits are formed due to wave action.
• Rocks of the Himalayas form the parent material. Thus the parent material of these soils is of transported origin.
• They are the largest soil group covering about 15 lakh sq km or about 46 per cent of the total area.
• They support more than 40% of the India’s population by providing the most productive agricultural lands.

Characteristics of Alluvial Soils

• They are immature and have weak profiles due to their recent origin.
• Most of the soil is Sandy and clayey soils are not uncommon.
• Pebbly and gravelly soils are rare. Kankar (calcareous concretions) beds are present in some regions along the river terraces.
• The soil is porous because of its loamy (equal proportion of sand and clay) nature.
• Porosity and texture provide good drainage and other conditions favorable for agriculture.
• These soils are constantly replenished by the recurrent floods.

Chemical properties of Alluvial Soils

• The proportion of nitrogen is generally low.
• The proportion of Potash, phosphoric acid and alkalies are adequate
• The proportion of Iron oxide and lime vary within a wide range.

Distribution of Alluvial Soils in India

• They occur all along the Indo-Gangetic-Brahmaputra plains except in few places where the top layer is covered by desert sand.
• They also occur in deltas of the Mahanadi, the Godavari, the Krishna and the Cauvery, where they are called deltaic alluvium (coastal alluvium)
• Some alluvial soils are found in the Narmada, Tapi valleys and Northern parts of Gujarat.

Crops in Alluvial Soils

• They are mostly flat and regular soils and are best suited for agriculture.
• They are best suited to irrigation and respond well to canal and well/tube-well irrigation.
• They yield splendid crops of rice, wheat, sugarcane, tobacco, cotton, jute, maize, oilseeds, vegetables and fruits.

Geological divisions of alluvial soils

• Geologically, the alluvium of the Great plain of India is divided into newer or younger khadar and older bhangar soils.

Bhabar

• The bhabar belt is about 8-16 km wide running along the Shiwalik foothills. It is a porous, northern most stretch of Indo-Gangetic plain.
• Rivers descending from the Himalayas deposit their load along the foothills in the form of alluvial fans. These alluvial fans (often pebbly soils) have merged together to build up the bhabar belt.
• The porosity of bhabar is the most unique feature. The porosity is due to deposition of huge number of pebbles and rock debris across the alluvial fans.
• The streams disappear once they reach the bhabar region because of this porosity. Therefore, the area is marked by dry river courses except in the rainy season.
• The area is not suitable for agriculture and only big trees with large roots thrive in this belt.

Terai

• Terai is an ill-drained, damp (marshy) and thickly forested narrow tract (15-30 km wide) to the south of Bhabar running parallel to it.
• The underground streams of the Bhabar belt re-emerge in this belt. It is a swampy lowland with silty soils.
• The terai soils are rich in nitrogen and organic matter but are deficient in phosphate.
• These soils are generally covered by tall grasses and forests but are suitable for a number of crops such as wheat, rice, sugarcane, jute etc..
• This thickly forested region provides shelter to a variety of wild life.

Bhangar

• The Bhangar is the older alluvium along the river beds forming terraces higher than the flood plain (about 30 metres above the flood level).
• It is of a more clayey composition and is generally dark colored.
• A few metres below the terrace of the bhangar are beds of lime nodules known as “Kankar”.

Khadar

• The Khadar is composed of newer alluvium and forms the flood plains along the river banks.
• The banks are flooded almost every year and a new layer of alluvium is deposited with every flood. This makes them the most fertile soils of Ganges.
• They are sandy clays and loams, more dry and leached, less calcareous and carbonaceous (less kankary). A new layer of alluvium is deposited by river flood almost every year.

Black Soils

• The parent material for most of the black soil are the volcanic rocks that were formed in the Deccan Plateau (Deccan and the Rajmahal trap).
• In Tamil Nadu, gneisses and schists form the parent material. The former are sufficiently deep while the later are generally shallow.
• These are the region of high temperature and low rainfall. It is, therefore, a soil group typical to the dry and hot regions of the Peninsula.

Characteristics of Black Soils

• A typical black soil is highly argillaceous [Geology (of rocks or sediment) consisting of or containing clay] with a large clay factor, 62 per cent or more.
• In general, black soils of uplands are of low fertility while those in the valleys are very fertile.
• The black soil is highly retentive of moisture. It swells greatly on accumulating moisture. Strenuous effort is required to work on such soil in rainy season as it gets very sticky.
• In summer, the moisture evaporates, the soil shrinks and is seamed with broad and deep cracks. The lower layers can still retain moisture. The cracks permits oxygenation of the soil to sufficient depths and the soil has extraordinary fertility.

Colour of Black Soils

• The black colour is due to the presence of a small proportion of titaniferous magnetite or iron and black constituents of the parent rock.
• In Tamil Nadu and parts of Andhra Pradesh, the black colour is derived from crystalline schists and basic gneisses.
• Various tints of the black colour such as deep black, medium black, shallow black , a mixture of red and black may be found in this group of soils.

Chemical Composition of Black Soils

• 10 per cent of alumina,
• 9-10 per cent of iron oxide,
• 6-8 per cent of lime and magnesium carbonates,
• Potash is variable (less than 0.5 per cent) and
• phosphates, nitrogen and humus are low.

Distribution of Black Soils

• Spread over 46 lakh sq km (16.6 per cent of the total area) across Maharashtra, Madhya Pradesh, parts of Karnataka, Telangana, Andhra Pradesh, Gujarat and Tamil Nadu.

Crops in Black Soils

• These soils are best suited for cotton crop. Hence these soils are called as regur and black cotton soils.
• Other major crops grown on the black soils include wheat, jowar, linseed, virginia tobacco, castor, sunflower and millets.
• Rice and sugarcane are equally important where irrigation facilities are available.
• Large varieties of vegetables and fruits are also successfully grown on the black soils.
• This soil has been used for growing a variety of crops for centuries without adding fertilizers and manures, with little or no evidence of exhaustion
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Factors that influence soil formation in Indian Conditions

Table of Contents

• Factors that influence soil formation in Indian Conditions
  • Parent Material
    • Ancient crystalline and metamorphic rocks
    • Cuddapah and Vindhyan rocks
    • Gondwana rocks
    • Deccan basalts
    • Tertiary and Mesozoic sedimentary rocks
  • Relief
  • Climate
  • Natural VegetationShareWhatsAppTweetEmail

Soil formation in Indian Conditions – Factors that influence soil formation: Parent Material – Gondwana rocks & Deccan basalts, Relief, Climate & Natural Vegetation.

Factors that influence soil formation in Indian Conditions

• Parent Material
• Relief
• Climate
• Natural Vegetation

Parent Material

• The rocks from which soils are formed are called parent materials.
• In most of the cases, the parent material determines the colouration, mineral composition and texture of the soil.
• In some cases, the soil formed may or may not have the same physical properties of the parent rock.
• Climatic factors induce chemical changes which also affect physical properties of the soil.
• The surface rocks are exposed to the process of weathering. In this process, the rocks are converted into fine grains and provide a base for the soil formation.
• In Indian Conditions, parent material is generally categorized into:

1. Ancient crystalline and metamorphic rocks
2. Cuddapah and Vindhyan rocks
3. Gondwana rocks
4. Deccan basalts
5. Tertiary and Mesozoic sedimentary rocks of extra peninsular India {Rock System}

Ancient crystalline and metamorphic rocks

• They are the Oldest rocks [(pre-Cambrian era)(formed due to solidification of molten magma about 4billion years ago)].
• They form the ‘Basement Complex’ of peninsular India.
• They are basically granites, gniesses and schists.
• These rocks are rich in ferromagnetic materials and give rise to red soils on weathering.
• The red colour of these soils is due to the presence of iron oxide.

Cuddapah and Vindhyan rocks

• They are ancient sedimentary rocks (4000 m thick).
• On weathering they give calcareous [containing calcium carbonate; chalky] and argillaceous [consisting of or containing clay] soils.
• The soil is mostly devoid of metalliferous minerals.

Gondwana rocks

• These rocks are also sedimentary in nature and they are much younger.
• On weathering they give rise to comparatively less mature soils.
• The soil is more or less of uniform character but of low fertility.

Deccan basalts

• Volcanic outburst over a vast area of the Peninsular India many hundred million years ago gave rise to Deccan Traps.
• Basaltic lava flowed out of fissures covering a vast area of about ten lakh sq km.
• Basalts are rich in titanium, magnetite, aluminium and magnesium.
• Consequently the weathering of these rocks has given rise to soils of darker colour.
• The is fertile with high moisture holding capacity and is popularly known as ‘regur’ or black cotton soil.

Tertiary and Mesozoic sedimentary rocks

• Rocks of extra peninsular (plains and Himalayas) India have given rise to soils with high porosity.
• These soils are generally immature recent and sub recent rocks, result in alluvial soils on weathering.
• Alluvial fertile soils consist of fine silts and clay. These soils have little relation with the original rocks.
• On the other hand, the soils of peninsular plateau are generally coarse-grained and are closely related to the parent rocks. The peninsular soils are generally less fertile.

Relief

• The relief is the most important factor for soil formation in places with steep slopes like the hilly regions, edges of plateaus etc.
• Soil erosion on barren slopes is rampant and it hinders soil formation. Example: Chambal ravines, higher reaches of Himalayas where there is minimal or no forest cover (most on the steep southern slopes) etc.
• The areas of low relief or gentle slope generally experience deposition and have deep soils. Example: Indo-Gangetic plain.
• The exceptions in the plateau are river basins where the soil layers are sufficiently deep.

Climate

• Temperature and rainfall are the most important factors in soil formation.
• They determine the effectiveness of weathering of the parent material, the quantity of water seeping through the soil and the type of micro-organisms present therein.
• Two different parent materials may develop the same soil in the same type of climate. Similarly, the same parent material may produce two different types of soils in two different types of climates.
• The crystalline granites produce laterite soil in relatively moist parts of the monsoonal region and non-laterite soil in drier areas.
• Hot summer and low rainfall develops black soil as is found in some parts of Tamil Nadu irrespective of the parent rock.
• In Rajasthan, both granite and sandstone give birth to sandy soil under arid climate.
• In arid and semi-arid regions, evaporation always exceeds precipitation. There is little vegetation and the soils badly lack humus content. Hence the soils are invariably of light colour.
• In Rajasthan and the adjoining arid and semi-arid regions, excess of evaporation makes soils lime accumulating. Hence the soil is pedocal in nature [Pedocal is a subdivision of the zonal soil order. It is a class of soil which forms in semiarid and arid regions. It is rich in calcium carbonate and has low soil organic matter].
• In cold climates of the Himalayan region, the process of vegetation decay is very slow and the soils are acidic in nature.

In areas of heavy rainfall and high temperature, the soils are red or lateritic. Why?

• Torrential rainfall during the rainy season washes the upper soil and leaches the materials into deeper horizon.
• During the dry summer season the evaporation exceeds precipitation and through capillary action iron and aluminium oxides are transported to the surface making the soil red.
• In areas of alternate wet and dry climate, the leached material which goes deep down in the horizon is brought up and the blazing sun bakes the top soil so hard that it resembles a brick. Therefore, this soil is called lateritic which literally means brick.

Natural Vegetation

• Natural vegetation reflects the combined effects of relief and climate.
• The formation and development of soil is very much influenced by the growth of vegetation.
• The decayed leaf material adds much needed humus to soil thereby increasing its fertility.
• The densely forested areas contain some of the best soils in India. There is a close relationship between the vegetation types and soil types in India
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Soil Types: Sandy, Clayey & Loamy | Soil Profile (Soil Horizon)

Table of Contents

• Soil
• Soil Types – Sandy-Clayey-Loamy
  • O Horizon
  • A Horizon or Surface soil
  • E horizon
  • B Horizon or Subsoil
  • C Horizon or Parent rock
  • R Horizon or BedrockShareWhatsAppTweetEmail

Soil – Soil Types: Sandy – Clayey – Loamy. Soil Profile – Soil Horizon: O horizon, A Horizon, E horizon, B Horizon, C Horizon or Parent rock, R Horizon or Bedrock.

Soil

• Soil is the thin top layer on the earth’s crust comprising rock particles mixed with organic matter.
• Pedology is the study of soils in their natural environment. Pedogenesis is the natural process of soil formation that includes a variety of processes such as weathering, leaching, calcification etc..
• The Soil formation is mainly related to the parent rock material, surface relief, climate and natural vegetation.
• The soil is formed by the breaking down of rocks by the action of wind, water and climate. This process is called

Soil Types – Sandy-Clayey-Loamy

• The soil is classified on the basis of the proportion of particles of various sizes.
• If soil contains greater proportion of big particles it is called sandy soil.
• If the proportion of fine particles is relatively higher, then it is called clayey soil.
• If the amount of large and fine particles is about the same, then the soil is called

1. Water can drain quickly through the spaces between the sand particles. So, sandy soils tend to be light, well aerated and dry.
2. Clay particles, being much smaller, pack tightly together, leaving little space for air. Unlike sandy soil, water can be held in the tiny gaps between the particles of clay. So clay soils have little air. But they are heavy as they hold more water than the sandy soils.
3. The best topsoil for growing plants is Loamy soil is a mixture of sand, clay and another type of soil particle known as silt. Silt occurs as a deposit in river beds. The size of the silt particles is between those of sand and clay. The loamy soil also has humus in it. It has the right water holding capacity for the growth of plants.

• Clayey and loamy soils are both suitable for growing cereals like wheat, and gram. Such soils are good at retaining water.
• For paddy, soils rich in clay and organic matter and having a good capacity to retain water are ideal.
• For lentils (masoor) and other pulses, loamy soils, which drain water easily, are required.
• For cotton, sandy loam or loam, which drain water easily and can hold plenty of air, are more suitable.

• A vertical section through different layers of the soil is called the soil profile.
• Each layer differs in feel (texture), colour, depth and chemical composition. These layers are referred to as
• A soil horizon is a layer generally parallel to the soil surface, whose physical characteristics differ from the layers above and beneath.
• Horizons are defined in most cases by obvious physical features, chiefly colour and texture.
• The uppermost horizon is generally dark in colour as it is rich in humus and minerals. The humus makes the soil fertile and provides nutrients to growing plants.
• This layer is generally soft, porous and can retain more water. It is called the topsoil or the A-horizon.
• The next layer has a lesser amount of humus but more of minerals. This layer is generally harder and more compact and is called the B-horizon or the middle layer.
• The third layer is the C-horizon, which is made up of small lumps of rocks with cracks.

O Horizon

• Layers dominated by organic material.
• Some O layers consist of undecomposed or partially decomposed litter (such as leaves, needles, twigs, moss, and lichens).
• They may be on top of either mineral or organic soils.

A Horizon or Surface soil

• It is the part of top soil.
• In this layer, organic matter is mixed with mineral matter.
• It is the layer of mineral soil with the most organic matter accumulation and soil life.
• This layer is depleted of (eluviated of) iron, clay, aluminum, organic compounds, and other soluble constituents.
• When depletion is pronounced, a lighter colored “E” subsurface soil horizon is apparent at the base of the “A” horizon.

E horizon

• “E” stands for eluviated layer.
• It is the horizon that has been significantly leached of clay, iron, and aluminum oxides, which leaves a concentration of resistant minerals, such as quartz, in the sand and silt sizes.
• These are present only in older, well-developed soils, and generally occur between the A and B horizons.

B Horizon or Subsoil

• It is subsurface layer reflecting chemical or physical alteration of parent material.
• This layer accumulates all the leached minerals from A and E horizon.
• Thus iron, clay, aluminum and organic compounds accumulate in this horizon [illuviation (opposite of eluviation)].

C Horizon or Parent rock

• Weathered parent material accumulates in this layer, i.e. the parent material in sedimentary deposits.
• It is a layer of large unbroken rocks.
• This layer may accumulate the more soluble compounds (inorganic material).

R Horizon or Bedrock

• This layer denotes the layer of partially weathered bedrock at the base of the soil profile.
• Unlike the above layers, R horizons largely comprise continuous masses of hard rock.
• Soils formed in situ will exhibit strong similarities to this bedrock layer.
• These areas of bedrock are under 50 feet of the other profiles
  .

Natural Vegetation of India: Moist Tropical, Dry Tropical, Montane Sub-tropical, Montane Temperate & Alpine Forests

Table of Contents

• Forests – Natural Vegetation of India
• Classification of Natural Vegetation of India
• Moist Tropical Forests
  • Tropical Wet Evergreen Forests or Rain Forests
  • Tropical Semi-Evergreen Forests
  • Tropical Moist Deciduous Forests
  • Littoral and Swamp Forests
• Dry Tropical Forests
  • Tropical Dry Evergreen Forests
    • Casuarina plantation
  • Tropical Dry Deciduous Forests
  • Tropical Thorn Forests
• Montane Sub-Tropical Forests
  • Sub-tropical Broad-leaved Hill Forests
  • Sub-tropical Moist Pine Forests
  • Sub-tropical Dry Evergreen Forests
• Montane Temperate Forests
  • Montane Wet Temperate Forests
  • Himalayan Moist Temperate Forests
  • Himalayan Dry Temperate Forests
• Alpine ForestsShareWhatsAppTweetEmail

Forests – Natural Vegetation of India – Classification of Natural Vegetation of India: Moist Tropical, Dry Tropical, Montane Sub-tropical, Montane Temperate, Alpine Forests.

Forests – Natural Vegetation of India

• Climate, soil and topography are the major factors that influence Natural Vegetation of a place.
• The main climatic factors are rainfall and temperature. The amount of annual rainfall has a great bearing on the type of vegetation.

Annual Rainfall	Type of Vegetation
200 cm or more	Evergreen Rain Forests
100 to 200 cm	Monsoon Deciduous Forests
50 to 100 cm	Drier Deciduous or Tropical Savanna
25 to 50 cm	Dry Thorny Scrub (Semi-arid)
Below 25 cm	Desert (Arid)

• Temperature is the major factor in Himalayas and other hilly regions with an elevation of more than 900 metres.
• As the temperature falls with altitude in the Himalayan region the vegetal cover changes with altitude from tropical to sub-tropical, temperate and finally alpine.
• Soil is an equally determining factor in few regions. Mangrove forests, swamp forests are some of the examples where soil is the major factor.
• Topography is responsible for certain minor types e.g. alpine flora, tidal forests, etc..

Classification of Natural Vegetation of India

• Classification of Natural Vegetation of India is primarily based on spatial and annual variations in rainfall. Temperature, soil and topography are also considered.
• India’s vegetation can be divided into 5 main types and 16 sub-types as given below.

A. Moist Tropical Forests

• Tropical Wet Evergreen
• Tropical Semi-Evergreen
• Tropical Moist Deciduous
• Littoral and Swamp

B. Dry Tropical Forests

• Tropical Dry Evergreen
• Tropical Dry Deciduous
• Tropical Thorn

C. Montane Sub-tropical Forests

• Sub-tropical broad leaved hill
• Sub-tropical moist hill (pine)
• Sub-tropical dry evergreen

D. Montane Temperate Forests

• Montane Wet Temperate
• Himalayan Moist Temperate
• Himalayan Dry Temperate

E. Alpine Forests

• Sub-Alpine
• Moist Alpine scrub
• Dry Alpine scrub

Forest Type in India	% of Total Area
Tropical Moist Deciduous	37
Tropical Dry Deciduous	28
Tropical Wet Evergreen	8
Sub-Tropical Moist Hill	6
Tropical Semi-Evergreen	4
Rest below 4 %

Moist Tropical Forests

Tropical Wet Evergreen Forests or Rain Forests

Climatic Conditions

• Annual rainfall exceeds 250 cm
• The annual temperature is about 25°-27°C
• The average annual humidity exceeds 77 per cent and
• The dry season is distinctly short.

Characteristics

• Evergreen: Due to high heat and high humidity, the trees of these forests do not shed their leaves together.
• Mesosphytic: Plants adopted to neither too dry nor too wet type climate.

What are mesophytes? Unlike hydrophytic plants, such as water lily or pondweed, that grow in saturated soil or water, or xerophytic plants, such as cactus, that grow in extremely dry soil, mesophytes are ordinary plants that exist between the two extremes. Mesophytic environments are marked by average to hot temperatures and soil that is neither too dry nor too wet.

• Lofty: The trees often reach 45 – 60 metres in height.
• Thick Canopy: From the air, the tropical rain forest appears like a thick canopy of foliage, broken only where it is crossed by large rivers or cleared for cultivation.
• All plants struggle upwards (most ephiphytes) for sunlight resulting in a peculiar layer arrangement. The entire morphology looks like a green carpet when viewed from above.

Epiphytes

• Less undergrowth: The sun light cannot reach the ground due to thick canopy. The undergrowth is formed mainly of bamboos, ferns, climbers, orchids, etc.

Distribution

• Western side of the Western Ghats (500 to 1370 metres above sea level).
• Some regions in the Purvanchal hills.
• In the Andaman and Nicobar Islands.

Timber

• Hardwood: The timber of these forests is fine-grained, hard and durable.
• It has high commercial value but it is highly challenging to exploit due to dense undergrowth, absence of pure stands and lack of transport facilities [Read previous posts on Climatic regions to understand how lumbering industry works in Equatorial Rainforests (hardwood) and Taiga Climatic (softwood) conditions].
  
• The important species of these forests are mahogany, mesua, white cedar, jamun, canes, bamboo etc.

Tropical Semi-Evergreen Forests

• They are transitional forests between tropical wet evergreen forests and tropical deciduous forests.
• They are comparatively drier areas compared to tropical wet evergreen forests.

Climatic Conditions

• Annual rainfall is 200-250 cm
• Mean annual temperature varies from 24°C to 27°C
• The relative humidity is about 75 per cent
• The dry season is not short like in tropical evergreen forests.

Distribution

• Western coast
• Assam
• Lower slopes of the Eastern Himalayas
• Odisha and
• Andamans.

Characteristics

• The semi-evergreen forests are less dense.
• They are more gregarious [living in flocks or colonies – more pure stands] than the wet evergreen forests.
• These forests are characterized by many species.
• Trees usually have buttressed trunks with abundant epiphytes.

Buttressed Trunks

• The important species are laurel, rosewood, mesua, thorny bamboo – Western Ghats, white cedar, Indian chestnut, champa, mango, etc. – Himalayan region.

Timber

• Hardwood: Similar to that in tropical evergreen forests except that these forests are less dense with more pure stands (timber industry here is better than in evergreen forests).

Tropical Moist Deciduous Forests

Climatic Conditions

• Annual rainfall 100 to 200 cm.
• Mean annual temperature of about 27°C
• The average annual relative humidity of 60 to 75 per cent.
• Spring (between winter and summer) and summer are dry.

Characteristics

• The trees drop their leaves during the spring and early summer when sufficient moisture is not available.
• The general appearance is bare in extreme summers (April-May).
• Tropical moist deciduous forests present irregular top storey [25 to 60 m].
• Heavily buttressed trees and fairly complete undergrowth.
• These forests occupy a much larger area than the evergreen forests but large tracts under these forests have been cleared for cultivation.

Distribution

• Belt running along the Western Ghats surrounding the belt of evergreen forests.
• A strip along the Shiwalik range including terai and bhabar from 77° E to 88° E.
• Manipur and Mizoram.
• Hills of eastern Madhya Pradesh and Chhattisgarh.
• Chota Nagpur Plateau.
• Most of Odisha.
• Parts of West Bengal and
• Andaman and Nicobar islands.

Timber

• These provide valuable timer like Teak.
• The main species found in these forests are teak, sal, laurel, rosewood, amla, jamun, bamboo, etc.
• It is comparatively easy to exploit these forests due to their high degree of gregariousness (more pure stands).

Littoral and Swamp Forests

• They can survive and grow both in fresh as well as brackish water (The mixture of seawater and fresh water in estuaries is called brackish water and its salinity can range from 0.5 to 35 ppt).
• Occur in and around the deltas, estuaries and creeks prone to tidal influences (delta or tidal forests).
• Littoral (relating to or on the shore of the sea or a lake) forests occur at several places along the coast.
• Swamp forests are confined to the deltas of the Ganga, the Mahanadi, the Godavari, the Krishna and the Cauvery.
• Dense mangroves occur all along the coastline in sheltered estuaries, tidal creeks, backwaters, salt marshes and mudflats. It provides useful fuel wood.
• The most pronounced and the densest is the Sunderban in the Ganga delta where the predominant species is Sundri (Heriteera).

Timber

• It provides hard and durable timber which is used for construction, building purposes and making boats.
• The important species found in these forests are Sundri, agar, rhizophora, screw pines, canes and palms, etc.

Dry Tropical Forests

Tropical Dry Evergreen Forests

Distribution

• Along the coasts of Tamil Nadu.

Climatic Conditions

• Annual rainfall of 100 cm [mostly from the north-east monsoon winds in October – December].
• Mean annual temperature is about 28°C.
• The mean humidity is about 75 per cent.
• The growth of evergreen forests in areas of such low rainfall is a bit strange.

Characteristics

• Short statured trees, up to 12 m high, with complete canopy.
• Bamboos and grasses not conspicuous.
• The important species are jamun, tamarind, neem, etc.
• Most of the land under these forests has been cleared for agriculture or casuarina plantations.

Casuarina plantation It resembles feathery conifer in general appearance. They are rapid-growing, carefree species for sites and climates as varied as coastal sand dunes, high mountain slopes, hot humid tropics, and semi-arid regions. They have the ability to fix atmospheric nitrogen. It grows 15 to 25 metres in height on an average. Casuarina plantation Distribution Casuarina is the most popular farm forestry in the states of Andhra Pradesh, Tamil Nadu, West Bengal, Odisha, Maharashtra, Gujarat, and Karnataka. Benefits Reduces damage in the event of natural calamities. Line planting in the coastal areas helps in controlling the wind force. It is also used for tourism promotion in view of its ornamental appearance. It provides top quality firewood. The wood is suitable for paper pulp and useful raw material for the manufacture of paper for writing, printing, and wrapping. It is got some serious medicinal values as well. Wasteland development The characteristics which make it a suitable species for wasteland development include adaptability to wide range of habitats, fast growth, salt tolerant, drought resistant, ability to reclaim land and stabilize sand dunes. Intercrops such as groundnut, cucumber, watermelons, sesamum, and pulses can also be raised along with the plantation.

Tropical Dry Deciduous Forests

Climatic Conditions

• Annual rainfall is 100-150 cm.

Characteristics

• These are similar to moist deciduous forests and shed their leaves in dry season.
• The major difference is that they can grow in areas of comparatively less rainfall.
• They represent a transitional type – moist deciduous on the wetter side and thorn forests on the drier side.
• They have closed but uneven canopy.
• The forests are composed of a mixture of a few species of deciduous trees rising up to a height of 20 metres.
• Undergrowth: Enough light reaches the ground to permit the growth of grass and climbers.

Distribution

• They occur in an irregular wide strip running from the foot of the Himalayas to Kanniyakumari except in Rajasthan, Western Ghats and West Bengal.
• The important species are teak, axlewood, rosewood, common bamboo, red sanders, laurel, satinwood, etc.
• Large tracts of this forest have been cleared for agricultural purposes.
• These forests have suffer from over grazing, fire, etc.

Tropical Thorn Forests

Climatic Conditions

• Annual rainfall less than 75 cm.
• Humidity is less than 50 per cent.
• Mean temperature is 25°-30°C.

Characteristics

• The trees are low (6 to 10 metres maximum) and widely scattered.
• Acacias and Euphorbias are very prominent.
• The Indian wild date is common. Some grasses also grow in the rainy season.

Distribution

• Rajasthan, south-western Punjab, western Haryana, Kachchh and neighbouring parts of Saurashtra.
• Here they degenerate into desert type in the Thar desert.
• Such forests also grow on the leeside of the Western Ghats covering large areas of Maharashtra, Karnataka, Telangana, Andhra Pradesh and Tamil Nadu.
• The important species are neem, babul, cactii, etc.

Montane Sub-Tropical Forests

Sub-tropical Broad-leaved Hill Forests

Climatic conditions

• Mean annual rainfall is 75 cm to 125 cm.
• Average annual temperature is 18°-21°C.
• Humidity is 80 per cent.

Distribution

• Eastern Himalayas to the east of 88°E longitude at altitudes varying from 1000 to 2000 m.

Characteristics

• Forests of evergreen species.
• Commonly found species are evergreen oaks, chestnuts, ash, beech, sals and pines.
• Climbers and epiphytes [a plant that grows non-parasitically on a tree or other plant] are common.
• These forests are not so distinct in the southern parts of the country. They occur only in the Nilgiri and Palni hills at 1070-1525 metres above sea level.
• It is a “stunted rain-forest” and is not so luxuriant as the true tropical evergreen.
• The higher parts of the Western Ghats such as Mahabaleshwar, the summits of the Satpura and the Maikal Range, highlands of Bastar and Mt. Abu in the Aravali Range carry sub-types of these forests.

Sub-tropical Moist Pine Forests

Distribution

• Western Himalayas between 73°E and 88°E longitudes at elevations between 1000 to 2000 metres above sea level.
• Some hilly regions of Arunachal Pradesh, Manipur, Naga Hills and Khasi Hills.

Timber

• Chir or Chil is the most dominant tree which forms pure stands.
• It provides valuable timber for furniture, boxes and buildings.
• It is also used for producing resin and turpentine.

Sub-tropical Dry Evergreen Forests

Distribution

• Found in the Bhabar, the Shiwaliks and the western Himalayas up to about 1000 metres above sea level.

Climatic Conditions

• Annual rainfall is 50-100 cm (15 to 25 cm in December-March).
• The summers are sufficiently hot and winters are very cold.

Characteristics

• Low scrub forest with small evergreen stunted trees and shrubs.
• Olive, acacia modesta and pistacia are the most predominant species.

Montane Temperate Forests

Montane Wet Temperate Forests

Climatic Conditions

• Grows at a height of 1800 to 3000 m above sea level
• Mean annual rainfall is 150 cm to 300 cm
• Mean annual temperature is about 11°C to 14°C and the
• Average relative humidity is over 80 per cent.

Distribution

• Higher hills of Tamil Nadu and Kerala, in the Eastern Himalayan region.

Characteristics

• These are closed evergreen forests. Trunks have large girth.
• Branches are clothed with mosses, ferns and other epiphytes.
• The trees rarely achieve a height of more than 6 metres.
• Deodar, Chilauni, Indian chestnut, birch, plum, machilus, cinnamomum, litsea, magnolia, blue pine, oak, hemlock, etc. are important species.

Himalayan Moist Temperate Forests

Climatic Conditions

• Annual rainfall varies from 150 cm to 250 cm

Distribution

• Occurs in the temperate zone of the Himalayas between 1500 and 3300 metres.
• Cover the entire length of this mountain range in Kashmir, Himachal Pradesh, Uttarakhand, Darjeeling and Sikkim.

Characteristics

• Mainly composed of coniferous species.
• Species occur in mostly pure strands.
• Trees are 30 to 50 m high.
• Pines, cedars, silver firs, spruce, etc. are most important trees.
• They form high but fairly open forest with shrubby undergrowth including oaks, rhododendrons and some bamboos.

Timber

• It provides fine wood which is of much use for construction, timber and railway sleepers.

Himalayan Dry Temperate Forests

Climatic Conditions

• Precipitation is below 100 cm and is mostly in the form of snow.

Characteristics

• Coniferous forests with xerophytic shrubs in which deodar, oak, ash, olive, etc are the main trees.

Distribution

• Such forests are found in the inner dry ranges of the Himalayas where south-west monsoon is very feeble.
• Such areas are in Ladakh, Lahul, Chamba, Kinnaur, Garhwal and Sikkim.

Alpine Forests

• Altitudes ranging between 2,900 to 3,500.
• These forests can be divided into: (1) sub-alpine; (2) moist alpine scrub and (3) dry alpine scrub.
• The sub-alpine forests occur lower alpine scrub and grasslands.
• It is a mixture of coniferous and broad-leaved trees in which the coniferous trees attain a height of about 30 m while the broad leaved trees reach only 10 m.
• Fir, spruce, rhododendron, etc. are important species.
• The moist alpine scrub is a low evergreen dense growth of rhododendron, birch etc. which occurs from 3,000 metres and extends upto snowline.
• The dry alpine scrub is the uppermost limit of scrub xerophytic, dwarf shrubs, over 3,500 metres above sea level and found in dry zone. Juniper, honeysuckle, artemesia etc. are important species
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