13 Forest ecosystem: Forest Types of India

J. S. Laura

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Module 25: Forest ecosystem: Forest Types of India

Learning Objectives:

  • Forest Cover of India
  • Main forest types of India
  • Distribution of different Forest types
  • Characteristics and composition of Forests

25.1. Introduction

 

Forests in India are very diverse in their composition with a long evolutionary and geological history, occurring under diverse climatic and edaphic conditions. The forests represent a very unique assemblage of both Indo-Malayan and Australian species indicating the geological and paleo-botanical value of these forests. The forest types of India were classified for the first time in 1936 by Sir HG Champion and compiled his monumental work ‘Preliminary Survey of Forest Type of India and Burma’ (Champion 1936). Champion and Seth classified India’s forests into 16 major types and about 221 sub-type groups; published ‘A Revised Survey of the Forest type of India’ in 1968. The detailed classification of forest types in India is based on climate, physiognomy, species composition, phenology, topography, soil factors, altitude, aspect, and biotic factors (Champion and Seth, 1968). The forests have been classified into six “major groups “, ranging from tropical to alpine These major groups have been further classified into 16 sub-groups on the basis of temperature and moisture regimes, and more than 200‘group categories’( see, Singh and Chaturvedi, 2017).

 

25.2 Major Forest Types

 

At the beginning of the 20th century about 30% of land in India was covered with forests. But by the year 2015 the forest cover has been reduced to 21.34%. In 2015, of the existing forests, about 2.61% are very dense forests (canopy cover 70% or more), 9.59% moderately dense forests (canopy cover 40% or more but less than 70%), 9.14% open forests (canopy cover 10% or more but less than 40%), and 1.26% scrub forests (canopy cover less than 10%) (FSI 2015). Mizoram, with 88.93 % of forest cover has the highest forest cover in percentage terms, followed by Lakshadweep (84.56%). Madhya Pradesh is having largest total forest cover (77, 462 km2) in India, followed by Arunachal Pradesh (67,248 km2) and Chhattisgarh (55,586 km2) (FSI 2015).

The forest types of India have been described on the basis of Champion and Seth (1968). The major forest types are given in Table 25.1.

 

 

 

25.2 I. MOIST TROPICAL FORESTS

 

Group 1: Tropical Wet Evergreen Forest

 

These forests are dense and show 30-45m tall canopy structure with four or five strata, generally found in regions having rainfall in the range of 2000 to > 3000 mm per year. The diversity of tree species is high in these forests. The forests are discontinuously distributed mainly along the Western Ghats, north-eastern India and Andaman and Nicobar. The northern and southern wet tropical evergreen forests are described in Table 25.2.

Group 2: Tropical Semi-Evergreen Forest

 

These forests occur in areas adjoining tropical wet evergreen, and form a transition between the evergreen and moist deciduous forests. Lower canopy is evergreen, whereas canopy species are deciduous for short periods during the dry seasons. Tropical Semi-evergreen Forest type comprises 13.79% of the Indian forest types.

These are dense, multi-strata, 24-36m in height. Rainfall ranges from 1500-2500mm per year. The canopies are not continuous and species richness lower as compared to evergreen forests. Buttressed stems occur in the case of both evergreen and deciduous trees ( e.g. Elaeocarpus spp, and Salmalia sp) Bamboos, canes, ferns, climbers are common. Epiphytes are abundant including many ferns and orchids.These are not climate climax formations, but occur as edaphic sub climax on shallow poor soils.The northern and southern tropical Semi-evergreen forests are described in Table25.3.

Group 3: Tropical Moist Deciduous Forest

 

These forests are common in areas where rainfall is 1000 to 2000 mm with a dry season of three to four months. Dominant trees are deciduous, lower storey trees are usually evergreen. The trees shed their leaves in winter months, again become flushed in March-April. These forests comprise 19.73% of India’s forest types (FSI 2011). These forests are widely distributed covering both in southern and northern states including Tamil Nadu, Arunachal Pradesh, Assam, Meghalaya, Mizoram, Bihar, West Bengal, Odisha, and Uttarakhand.

 

These forests are usually 2 to 3 strata with a much lower number of species as compared with the tropical evergreen and semi evergreen forests. The canopy trees are light demanding, middle ones are shade tolerant species of shrubs and young trees, and on ground floor are present herbs and saplings. Climbers are abundant. The northern and southern tropical moist deciduous forests are described in Table 25.4.

Group 4: Littoral and Swamp Forests

 

These forests consist of evergreen species of varying densities and height, usually associated with mesic habitats. These forests are mostly in their developmental stage and are seral in nature.

  1. The littoral forests occur along the coast in the Andaman and Nicobar, Andhra Pradesh, Odisha, and Tamil Nadu. The most characteristic species is tall and evergreen Casuarina on  sandy beaches and dunes along the sea face. In Andaman, the forests are dominated by Manilkara littoralis.
  2. The tidal and swamp forests (mangrove scrub) are dominated by several evergreen and semi-evergreen species in deltas of the Ganga and the Brahmaputra rivers.
  3. Mangroves are found along the east and west coasts of India, the Andaman and Nicobar Islands, the Gulf of Kachchh and Khambat (Gujarat). Sundarban (40% in West Bengal) is the largest mangrove in the world. Mangrove forests are generally dominated by trees of the genera – Rhizophora, Avicennia, Sonneratia, Bruguiera, and Ceriops. Some genera like Heritiera and Xylocarpus. On the drier areas within the salt water mangrove scrub/forest are found palm swamp.
  4. Tropical fresh water swamps such as Myristica swamp forest occur in Travancore, Kerala, contain species such as Myristica spp., Lagerstroemia speciosa.
  5. The species like Baringtonia spp, and Syzygium cumini, are found in swamps forests of UP and West Bengal.

 

25.2.2. II. DRY TROPICAL FORESTS

 

Group 5: Tropical Dry Deciduous Forests

 

These are largest forest type of India covering about 38.2% of the forest area of the country. Tropical dry forests occur in climates exhibiting a marked seasonality in rainfall and prolonged drought period over the annual cycle. These forests consist of trees less than 25m high, with a light demanding canopy consisting of deciduous trees. These forests occur from Kanyakumari to the foothills of the Himalaya in low rainfall areas of 800 to 1200mm; large areas of these forests are suitable habitats for wildlife.

 

Dry teak and dry sal communities predominate in the southern and northern regions, respectively. In some areas a mixture of trees like Anogeissus pendula, Boswellia serrata, Hardwickia binata,Acacia nilotica, Madhuca indica, and Butea monosperma occupy the area. Acacia catechu and Dalbergia sissoo are conspicuously present on newly formed soils. The northern and southern tropical Dry Deciduous forests are described in Table 25.5.

Group 6: Tropical Thorn Forests

 

These forests are found in low rainfall areas (200 to 800mm) of northern India, peninsular India and central India. Moisture availability is limiting for plant growth. The trees experience prolonged dry periods. The tree height ranges from six to nine meters.

 

Southern Tropical Thorn Forests Occur in Maharashtra, Tamil Nadu and AP. In south India, important species are Acacia chundra , Acacia planifrons and Acacia catechu..

Northern Tropical Thorn Forests occur in semiarid regions of Rajasthan, Punjab, Haryana, northern Gujarat, MP, UP, and Delhi.

 

  1. These forests are open, consisting of short trees, generally belonging to thorny tree species. The desert thorn type consist of Acacia senegal, Prosopis spicigera, Prosopis cineraria, Acacia leucophloea, Acacia nilotica, Ziziphus spp, and Salvadora spp. Acacia tortilis and Prosopis chilensis have been widely planted in this region.
  2. The desert dune scrub are very open, irregular formations of stunted trees and bushes, these are sparse and thorny. The main species are Acacia senegal, Prosopis spicigera, Acacia Arabica, Tamarix aphylla, Salvadora oleoides.

 

Group 7: Tropical Dry Evergreen Forests

 

The forests are restricted in distribution to Karnataka coast, also reported from the east coast in AP. These are low growing forests; trees are of 9-12 m height, and form a complete canopy. Most conspicuous trees are Manilkara hexandra, Memecylon edule along with Diaspyros, Eugenia, Chloroxylon, Albizzia amara. There is a high diversity of trees, shrubs and herbs in these forests.

 

25.2.3. (III) MONTANE SUBTROPICAL FORESTS

Group 8: Subtropical Broad Leaved Hill Forests

 

These forests are of the following types:

 

  1. Southern Subtropical Broad Leaved Hill Forests

 

In south India, these forests are found in the hill slopes and tops at about 1000 to 1700m height in Nilgiri, Palani, Tirunelveli, and Mercara hills. Main trees are Calophyllum elatum, Eugenia spp., Dalbergia latifolia, Anogeissus latifolia, Emblica officinalis, Olea dioca, and Phoenix humilis.

  1. Central Indian Subtropical Hill Forests

Hill top forests occur above 1200m in Madhya Pradesh (Pachmarhi), Bihar, Odisha. In Pachmarhi hills, Manilkara hexandra, Mangifera, Syzygium cumini are conspicuous trees.

 

  • Northern Subtropical Broad Leaved Hill Forests

 

Occur in Arunachal Pradesh, Manipur, Mizoram, Meghalaya, Nagaland Sikkim, and west Bengal represented by east Himalayan subtropical wet hill forest, Altitude 1000-to 2000m, Occur in Khasi, Jainti and adjacent hills, dense evergreen forests , rarely exceeding 20m height. Important tree species are Quercus, Castanopsis, Alnus, Prunus, Betula and Schima. There is heavy growth of epiphytic mosses, ferns and phanerogams. Subtropical broad leaved hill forest dominated by Quercus serrata, Eugenia praecox, Schima wallichii,Rhus succidanea located located at Imphal, Manipur is shown in Fig.25.3.

 

Group 9: Sub-Tropical Pine Forests

 

Sub-tropical chir pine (Pinus roxburghii) forests occur throughout the central and western Himalaya between 1000 to 1800m; distributed in Haryana, Himachal Pradesh, Jammu and Kashmir, Punjab and Uttrakhand. Pinus roxburghii along with broad leaved species is the main characteristics of these forests. Climbers and bamboos are absent. A view of Sub-tropical chir pine (Pinus roxburghii) forest in Morni hills in north-east Haryana is shown in Fig.25.4.

 

Fig25.4. A view of Sub-tropical chir pine (Pinus roxburghii) forest in Morni hills in north-east Haryana, northern India ( Photo SR Gupta)

 

The forests of Pinus keysia along with Schima wallichii occur in Khasi and Naga Hills, and Manipur hills, in eastern Himalaya (Fig.25.5). Pinus kesiya is often a pioneer in deforested secondary vegetation, especially if fire has been a factor in the disturbance.

These forests are distributed in Bhabar tract, Shiwalik hills, and the foothills of western Himalaya. In Punjab, Uttrakhand, and Himachal Pradesh, Olea cuspidata is found on alluvial ground of wider valleys. In Jammu and Kashmir, the dominant species of these scrub forests are Olea cuspidate, Acacia modesta, and Dodonaea viscosa

 

25.2.4 IV. MONTANE TEMPERATE FORESTS

 

Group 11: Montane Wet Temperate Forest

 

The southern Montane wet temperate forests are closed evergreen forest, trees are mostly short boled (not exceeding 6m), and highly branched. The branches are clothed with mosses, ferns and other epiphytes, woody climbers are common. The northern Montane wet temperate forests are a characteristic feature of the eastern Himalaya and are found between 1800 m and 3000 m elevation in high rainfall areas ( >2000mm rainfall);

 

The northern and southern Montane wet temperate forests  of India are described in Table25.6.

 

Group 12: Himalayan Moist Temperate Forests

 

These forests extend the whole length of the Himalayan region between the sub-tropical pine forest and sub-alpine forests. Altitude ranges from 1500m to 3300m. These are concentrated in the central and western Himalaya, except in areas where rainfall is below 1000 mm. Distributed in Kashmir, Himachal Pradesh, Punjab, Uttrakhand, Darjeeling district of west Bengal, Assam, and Sikkim.

  1. Several species of oak predominate in the temperate forests including Quercus leucotrichophora, Quercus. Floribunda, Quercus incana, Quercus semecarpifolia, Quercus dilatata, Q. larginosa. All oak species in Himalayan region are evergreen showing leaf fall in summer, but are never leafless. There are four strata, 25-30m height, tree canopy is dense, herbaceous layer not well developed, grasses generally lacking, and rich in epiphytes. A view of temperate oak forest at Munsiyari Pithoragarh, Uttarakhand in Kumaun Himalaya is shown in Fig.25.7.
  2. Most Cedrus deodara forests form pure stands, canopy is fairly complete, boles are straight and tall (30-40m), There are scattered oaks and Rhododendron under the conifers. The evergreen Cedrus deodara forest surrounding the Khajjiar lake located at 1920 m above mean sea level in Khajjair, Chamba district, Himachal Pradesh in western Himalaya is shown in Fig.25.8.
  3. As the altitude increases, the upper form consisting of Abies pindrow, Picea smithiana, and Quercus semecarpifolia becomes dominant.
  4. The eastern Himalayan hills are occupied by Quercus. lineata, Quercus lamellosa, Quercus pachyphylla, Rhododendron spp., Tsuga dumosa, Picea spinulosa and Abies densa.
  5. Cupressus torulosa is a conspicuous species found on limestone rocks from Chamba (Himachal Pradesh) to the Aka hills at 1800 to 2800 m.

Group 13: Himalayan Dry Temperate Forests

 

Conifers predominate, distributed on 1700 to 3000m altitude, in the inner ranges of Himalaya, rainfall usually less than 1000mm mostly received as snow in winter months. Distributed in Kashmir, Ladhakh, Lahaul, Chamba, inner Garhwal, and Sikkim.

 

  • Coniferous forests are tall (30-35m) and have evergreen canopy.
  • These forests consist of both coniferous and broad-leaved species. In the western Himalaya, the characteristic species are Pinus gerardiana, Cedrus deodara and Juniperus. At higher elevation, Abies pindrow, and Pinus wallichiana are found.
  • In the eastern Himalaya, the common species are from Abies and Picea. In higher hills, Juniperus wallichiana is common.
  • Locally, between 2500 and 4000 m elevation, a few other species like Larix griffithiana, Populus eupheretica, Salix spp., Hippophoe spp. and Myricaria spp. also occur.

 

25.2.5. (V) SUB-ALPINE FORESTS

Group 14: Sub-Alpine Forests

 

The subalpine forests occur throughout the Himalaya above 3000 m elevation up to the tree limit., rainfall 83-600mm. The forests are mainly evergreen, Rhododendron is common constituent. Tall trees are conifers; Betula utilis is present as the largest deciduous tree and associated with genera like Quercus semecarpifolia, Sorbus, and Rhododendron sp.

  • Western Himalaya sub-alpine forests reported from Jammu and Kashmir, Himachal Pradesh, and Uttrakhand. In the western Himalaya, there are two types of forests (i) Abies spectabilis and Betula utilis , (ii) west Himalayan sub-alpine birch/fir forest.
  • In the eastern Himalaya, these forests occur above 3000m. These forests are distributed in Arunachal Pradesh, Sikkim, and west Bengal. There is predominance of Abies densa and Betula utilis, and Rhododendron spp. These are climax formations, self generating with marked resilience.

 

25.2.6. (VI) ALPINE FORESTS

Group 15: Moist- Alpine Scrub

 

Moist Alpine Scrub occurs throughout Himalaya, above timber line to 5,500m altitude, composed entirely of species of Rhododendron with some birch (Betula) and other deciduous trees. The tree trunks are short and highly branched, moss and ferns cover the ground. A thick layer of humus is present and soil is generally wet.

  • In Kumaun, Uttrakhand, Betula utilis and Rhododendron campanulatum scrub forest occur. Rhododendron- Lonicera association occurs in Uttrakhand, in inner Himalaya.
  • In eastern Himalaya, dense Rhododendron thickets occur at 3350-4600m altitude. These forests are reported from Arunachal Pradesh, Sikkim and west Bengal.

 

Group 16: Dry- Alpine Scrub

It is a xerophytic formation, having predominance of dwarf shrubs; rainfall < 370mm per year. Characteristic plants are Juniperus wallichiana, Lonicera spp, Potentilla spp. Vegetation along the streams is composed of Salix, Myricaria, and Hippophae rhamnoides. These scrub forests are distributed in Jammu and Kashmir, Himachal Pradesh, Uttrakhand, and Arunachal Pradesh. In eastern Himalaya, Juniperus recurva and Juniperus wallichiana occur at an altitude ranging from 3000 to 4600m.

 

25.3. New Classification of Forest Types of India

 

Recently, the new classification of forest types has been proposed reflecting the present ecological, climatic, bio-geographic and edaphic influences on the vegetation composition and stand formation  (see ICFRE 2013; Bahuguna et al. 2016). India’s forest types are very diverse in their compositions with a long evolutionary and geological history, occurring under many climatic and edaphic conditions. They have been undergoing significant changes in the composition of forests since the forest types were revised by Champion and Seth (1968).

 

The revised classification of forests has been based on the field survey covering more than 200 forest types and subtypes representing very diverse climatic and edaphic conditions throughout the country. Data were collected from the field surveys in terms of forest types, basal area, importance value index, stem density and diversity indexes including similarity indexes. Impact of climate change on the vegetation has been critically examined. The new classification of forest types reflects the present ecological, climatic, bio-geographic and edaphic influences on the vegetation composition and stand formation. In the proposed new classification, 10 major groups and 48 sub-groups have been were identified (ICFRE 2013; Bahuguna et al. 2016). The study has reported many changes occurring at species and forest subtypes levels. There are some positive and negative changes in different forest types. Some trends in the new classification of forest types are summarized as follows:

 

  1. The species level changes were observed largely in Shorea robusta (Sal), Tectona grandis (Teak) and Bamboo forests with regard to their distribution and species density. The study has revealed that teak is found absent from very moist and moist teak sub-type, and occurrence of many moist deciduous and semi-evergreen species.
  2. In central India, the decline of Shorea robusta (Sal) and occurrence of dry deciduous species, fragmentation and changes in the species composition due to anthropogenic and climate changes.
  3. The vegetation composition, particularly on the alpine flora is experiencing the effect of climate change.
  4. There are changes in species composition of Shola forests and evergreen forests.
  5. The forests in Andhra Pradesh, Karnataka and Gujarat have shown positive changes in the forest composition and density.
  6. Analysis based on national level data showed change in temperature and rainfall patterns reveal that many forests are moving towards drier conditions, particularly the temperate forests. There are changes in the pattern of distributions of Oaks and Conifers.
  7. The blue pine (Pinus wallichiana) found in the higher elevations up to 1700 m is now found in still higher elevations up to 2700 m showing a the shift in the tree lines towards higher elevations.

 

25.4. Summary

 

  1. Champion and Seth (1968) gave the detailed classification of forest types in India based on climate, physiognomy, species composition, phenology, topography, soil factors, altitude, aspect, and biotic factors.
  2. The forests have been classified into six major forest types and 16 major groups on the basis of temperature and moisture regimes.
  3.  The tropical wet evergreen forests are dense and show 30-45m tall canopy structure with four or five strata, generally found in the Western Ghats, north-eastern India and Andaman and Nicobar having rainfall in the range of 2000 to > 3000 mm.
  4. The tropical semi-evergreen forests occur in areas adjoining tropical wet evergreen, and form a transition between evergreen and moist deciduous forests.
  5. Tropical Moist Deciduous Forests are common in areas where rainfall is 1000 to 2000 mm with a dry season of three to four months, widely distributed covering both southern and northern states.
  6. Mangroves are found along the east and west coasts of India, the Andaman and Nicobar Islands. Sundarban (is the largest mangrove in the world).
  7. Tropical Dry Deciduous Forests are largest forest type of India covering about 40% of the
  8. forest area of the country, dry teak (Tectona grandis)and dry sal (Shorea robusta) forests predominate in the southern and northern regions of India, respectively.
  9. Tropical thorn forests are found in low rainfall areas of northern India, peninsular India and central India, moisture availability is limiting for plant growth, the trees experience prolonged dry periods.
  10. Subtropical Broad Leaved Hill Forests occur in the hill slopes and tops at about 1000 to 1700m height in south India and northern India.
  11. Sub-tropical chir pine (Pinus roxburghii) forests occur throughout the central and western Himalaya between 1000 to 1800m. The forests of Pinus keysia occur in Khasi and Naga Hills and Manipur hills in eastern Himalaya.
  12. The southern Montane wet temperate forests Occur in high hills of Tamil Nadu and Kerala on the, Anamalai, Palni and Tiruneveli hills from about 1,500 m upwards. Tiruneveli
  13. Northern Montane wet temperate forests are a characteristic feature of the eastern Himalaya and are found between 1800 m and 3000 m elevation in high rainfall areas ( >2000mm rainfall).
  14. Himalayan Moist Temperate Forests are distributed in northern India at altitude ranging from 1500m to 3300m. Several species of oak predominate in the temperate forests
  15. The Himalayan Dry Temperate Forest: Conifers predominate, 1700 to 3000m altitude, in the inner ranges of Himalaya, rainfall usually less than 1000mm.
  16. Sub-Alpine Forests occur throughout the Himalaya above 3000 m elevation up to the tree limit.
  17. The new classification of forest types has been proposed reflecting the present ecological, climatic, bio-geographic and edaphic influences on the vegetation composition and stand formation.
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References

 

  • Bahuguna,V.K.. Swaminath, M.H,    Tripathi, S. ,     Singh, T.P. ,     Rawat V.R.S.,     and Rawat, R.S.. (2016). Revisiting forest types of India. International Forestry Review 18:135-145.
  • Champion, H.G. (1936). A preliminary survey of the forest types of India and Burma. Indian Forest Records (n.s.) Silva. X (I).
  • Champion, H.G. and Seth, S.K. (1968). A Revised Survey of the Forest Types of India. The Manager of Publications, Delhi-6.
  • FSI (2011). Atlas Forest Types of India. Forest Survey of India, Ministry of Environment of Forests, Dehradun.
  • FSI (2015). India State of Forest Report. Forest Survey of India, Ministry of Environment of Forests, Dehradun.
  • ICFRE 2013. Forest Types of India. Revisited. 2013. Indian Council of Forestry Research and Education, Dehradun.
  • Myers,  N.,  Mittermeier,  R.  A.,  Mittermeier,  C.  G.,  da  Fonseca,  G.A.B.  and  Kent,  J.  (2000). Biodiversity hotspots for conservation priorities. Nature 403: 853-856.
  • Pascal,JP, , Ramesh, BR and Dario DE Franceschi. (2004). Wet evergreen forest types of the southern Western Ghats, India. Tropical Ecology 45: 281-292.
  • Singh,  J  S  and  Chaturvedi,  R.K.  (2017).  Diversity  of  Ecosystem  Types  in  India:  A  Review. Proceedings of the Indian National Science Academy 83: 569-594