Vegetation - Geography

Table of Contents
1. Tropical Evergreen or Rainforests
2. Tropical Deciduous Forests (Monsoon Forests)
3. Montane Forests
4. Scrub and Thorn Forests
5. Desert and Semi-desert Vegetation
6. Mangrove Forests (Tidal or Littoral)
7. Geographical Distribution of Major Forest Types in India
8. Exotic and Boreal Flora
9. Vegetation Zonation in the Himalayas
10. Vegetation Life Cycle, Ecological Balance and Adaptation
11. Depletion of Forests in India - Causes and Conservation
12. Benefits of Forests
13. Forest Policy of India
14. Afforestation Programmes
15. Social Forestry - Objectives
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Tropical Evergreen or Rainforests

Tropical evergreen forests, also called rainforests, are characterised by trees that do not have a distinct season of shedding leaves and therefore remain evergreen throughout the year. They occur where the mean annual temperature is about 25°C-27°C and annual rainfall exceeds 200 cm. These forests commonly grow on the windward or rainy slopes facing the monsoon currents.

Major Indian regions with tropical evergreen forests include the western parts of the Western Ghats (parts of Maharashtra, Karnataka and Kerala), the eastern Himalayas (Terai region), the north-eastern hills (Lushai, Garo, Khasi, Jaintia and other hills) and much of the Andaman Islands.

Rainforest

Tropical evergreen forests have a dense multi-layered canopy with tall trees often reaching up to 45 m, abundant climbers and epiphytes, and a rich undergrowth of bamboo and ferns. These forests yield valuable hardwoods such as rosewood, ebony and ironwood used for furniture, construction and railway sleepers.

Tropical Deciduous Forests (Monsoon Forests)

Also called monsoon forests, tropical deciduous forests form the bulk of natural forest cover across India. They occur where annual rainfall ranges roughly between 100 cm and 200 cm (areas commonly stated as 150-200 cm in many sources). Most trees here are deciduous: they shed their leaves for a short period (typically several weeks) during the hot, dry season. Leaf-shedding generally takes place between early March and the end of April, and because species shed at different times the forest is rarely entirely bare.

Deciduous forests are of two main types:

• Moist deciduous forests
• Dry deciduous forests

Moist deciduous forests occur where moisture conditions are higher (eastern slopes of the Western Ghats, much of the north-eastern peninsula around the Chhotanagpur plateau covering eastern Madhya Pradesh, South Bihar and West Odisha, and along the Shivaliks including bhabhar and terai). Teak (Tectona grandis) is an important species in these forests.

Dry deciduous forests occupy the drier portions of the deciduous belt (areas with rainfall closer to 100-150 cm). They have a more open, stunted and widely spaced tree cover, though many species are similar to moist deciduous forests.

Deciduous forest

Deciduous forests are economically important because they contain numerous commercially valuable timber species and often occur in gregarious (dense single-species) stands, which makes exploitation easier. Important trees and their uses include:

• Sal - very hard and heavy timber, resistant to termites; common in North, Central and North-East India (Bihar, Uttar Pradesh, Odisha, Madhya Pradesh, Tripura, Assam). Used for railway sleepers and house construction.
• Teak (Tectona grandis) - yields durable timber used in shipbuilding, furniture and house construction; seasoned teak resists termites and does not corrode iron nails. Found in Madhya Pradesh, Assam, Odisha, Bihar, Maharashtra and Tamil Nadu.
• Sandal - sandalwood for handicrafts and aromatic oil used in perfumery; mainly in Karnataka.
• Semul - soft white timber used for packing cases, matchboxes and toys; found in Assam, Bihar and Tamil Nadu.
• Myrobalan - used in tanning leather and dyeing textiles.
• Mahua - flowers are edible and used for distillation of alcohol; khair provides material used as a chewing substance with betel leaves.

Montane Forests

In mountainous regions vegetation is arranged in a vertical succession of belts - from tropical types in the lowlands to tundra near the snowline - compressed into a relatively short altitude range. Local factors such as aspect (sunny versus shaded slopes) and relief cause variations in vegetation at the same altitude.

The montane forests of India are commonly discussed under two regional headings:

Montane (Southern)

The Nilgiri and Palni hills and other southern highlands have wet hill forests between about 1,070 m and 1,525 m. Below these wet hill forests occur stunted rainforest types and above them temperate forests (locally called sholas) develop. Shola forests are dense but low, with rich undergrowth including many epiphytes, mosses and ferns. Characteristic species include magnolia, laurel, rhododendron, elm and prunus. Several exotic species such as eucalyptus, cinchona and wattle have been introduced in parts of the southern montane region.

Montane forest

Montane (Northern)

The foothills of the Himalayas (Shivaliks) have tropical moist deciduous flora, with sal often dominant and bamboo common. Wet hill forests in the Himalaya occur roughly between 1,000 m and 2,000 m, with evergreen oaks, chestnut species, ash and beech, together with numerous climbers and epiphytes.

In the northeastern hills at similar altitudes, where rainfall is heavy, sub-tropical pine forests with chir (Pinus roxburghii) dominate; chir is valuable for resin extraction and timber.

Between about 1,600 m and 3,300 m are the moist temperate or coniferous forests: pine, cedar, silver fir and spruce form the canopy, with an understorey of oak, rhododendron, laurel and some bamboo. In the inner Himalaya and in drier regions where rainfall falls below ~100 cm, trees such as deodar and chilgoza (pine producing edible seeds) are common.

From approximately 2,881 m to 3,640 m a dense shrubby belt of alpine forests exists, including silver fir, juniper, pine, birch and rhododendron. Alpine forests grade into alpine grasslands and pastures as altitude increases.

Scrub and Thorn Forests

Scrub and thorn forests occur where annual rainfall is scanty (generally less than 100 cm) and is insufficient to support tall tree growth. They extend across the north-western parts of India from Saurashtra southwards and across the Punjab plains to the north. Eastwards they reach northern Madhya Pradesh (Malwa plateau) and south-west Uttar Pradesh covering parts of Bundelkhand. Characteristic trees include khair, kikar, babul and date palms (khajur). Trees are typically stunted, widely spaced and often thorny; these forests gradually give way to scrubs and thorny bushes typical of arid regions.

Desert and Semi-desert Vegetation

Desert and semi-desert vegetation occurs where rainfall is very low (often below 25 cm) and mean annual temperatures are high (about 25°C-27°C). Vegetation is dominated by hardy, drought-adapted species such as thorny bushes, acacia, wild berries, babul and kikar. Plants are generally low (6-10 m), have long roots and are armed with thorns or spines to reduce herbivory and transpiration. Such vegetation is found in Rajasthan, Kutch, Saurashtra, south-western Punjab and parts of the Deccan.

Mangrove Forests (Tidal or Littoral)

Mangrove forests are tidal forests found along coasts and in river deltas where vegetation tolerates alternating salt and fresh water conditions. Mangrove trees have specialised aerial or stilt roots that support the plants in soft, shifting mud and allow gas exchange during high tide and low tide - an important adaptation to the tidal environment.

Mangrove forest

In India, mangroves occur in almost continuous stretches along the deltas of the Ganga, Mahanadi, Godavari, Krishna and Cauvery, and around the Andaman and Nicobar islands. On the east coast the mangrove belt is extensive; the Sundarbans (the Ganga delta) are the most famous mangrove tracts, dominated by the sundari tree. Other important species include nagarajan and hintal. Mangroves provide fuel, wood and protect coasts against erosion and storm surges.

Geographical Distribution of Major Forest Types in India

• West Tropical Evergreen Forests - found where annual rainfall exceeds 250 cm (Western Ghats and parts of Assam). Representative species: rubber, mahogany, ironwood and other tropical hardwoods.
• Monsoon (Deciduous) Forests - occupy regions with 150-250 cm rainfall (Chota Nagpur Plateau, parts of Assam and southern slopes of the Himalayas). Key species: tea (in plantations) and sal in natural forests.
• Dry Forests - occur in broad belts with less than ~100 cm annual rainfall (Punjab, Haryana, Uttar Pradesh, Deccan Plateau). Useful trees include khair and sheesham.
• Coniferous Forests - occupy upland Himalayan regions (variable with altitude and rainfall) and constitute about 6% of India's forest area. Important softwoods: deodar, pine, fir and spruce.
• Tidal (Mangrove) Forests - found in coastal deltas (Ganga, Mahanadi, Godavari, Krishna, Cauvery); the Sundarbans are the most extensive mangrove tract in India.

Exotic and Boreal Flora

Nearly 40% of plant species found in India originated outside the subcontinent and are termed exotic plants. Many were introduced from the Sino-Tibetan region, Africa and the Indo-Malaysian region as ornamental or economic plants. Under hot, wet tropical conditions some exotic species become invasive weeds and rapidly spread, reducing useful land cover, displacing native economic plants and sometimes spreading disease.

Examples of problematic exotics include lantana and water hyacinth. Water hyacinth has been called the "Terror of Bengal" for clogging rivers, tanks, canals and other watercourses.

The term boreal is used for plant species or flora originating from cooler temperate zones (often referring to species that came from or are similar to those in the Sino-Tibetan regions) and established in parts of India.

Vegetation Zonation in the Himalayas

The Himalayas show a vertical succession of vegetation zones from tropical types in the southern foothills up to alpine and tundra-like communities at high altitude. The main belts are:

• Tropical West Deciduous Forests - up to about 1,000 m on the southern foothills; dense sal forests occur where rainfall is high.
• Temperate Forests - wet temperate forests up to around 2,000 m with evergreen oaks, chestnut and some pines.
• Broad-leaved Evergreen Forests - between roughly 2,000 m and 3,000 m with oaks, laurels and chestnuts (regional variation applies).
• Coniferous Forests - up to about 3,500 m; include pine, cedar, silver fir, spruce and deodar (valuable for timber and railway sleepers).
• Alpine Pastures - beyond about 3,500 m; short grasses used for seasonal grazing (transhumance) by nomadic pastoralists such as the Gujjars.

Vegetation Life Cycle, Ecological Balance and Adaptation

Vegetation communities are closely linked to their environment. Each plant species grows as part of a community adapted to particular soil, climate, temperature and slope conditions. The development of vegetation follows a sequence of life stages - young, mature and old - and the timing and duration of these stages vary among species. Life cycles and community structure are controlled by environmental factors such as water availability, rainfall patterns, sunlight, soil properties and topography.

Climax communities develop where vegetation reaches a relatively stable, self-sustaining state under the prevailing environmental conditions. For example, teak often forms dense stands in which other species may not regenerate easily - a form of climax community adapted to local conditions.

Depletion of Forests in India - Causes and Conservation

A country ideally needs roughly one-third of its land under forest for a healthy ecological balance; India's forest cover has historically been lower. At present India's recorded forest area is substantially less than one-third (commonly cited figures are in the low-20% range), and high-quality natural forests have been reduced in extent due to multiple causes:

• Clearing of extensive forest areas for agriculture and settlement
• Practice of shifting cultivation (slash-and-burn)
• Heavy soil erosion and denudation in catchment areas
• Overgrazing of pastures
• Cutting of trees for timber, fuel and other uses
• Human occupancy and land conversion for non-forest uses

Population pressure increases demand for arable land, fuelwood and pastures, and forests are heavily exploited for industrial and domestic needs. Conservation measures therefore include afforestation, reforestation, grassland regeneration, improved silviculture, use of fast-growing species, and expansion of area under forests through planned programmes.

Benefits of Forests

Forests provide both indirect (ecological) and direct economic benefits.

Indirect (ecological) benefits

• Influence on local and regional climate, moderation of temperature and humidity.
• Conservation of soil and reduction of erosion; regulation of moisture and streamflow.
• Maintenance of perennial flow in hill streams and reduction of flood intensity downstream.
• Carbon recycling and maintenance of atmospheric gas balance (oxygen and carbon dioxide).

Direct (economic) benefits

• Raw materials for forest-based industries: pulp and paper, newsprint, rayon, saw-milling, wood-panel products, matches, resins, medicinal herbs, lac and other products.
• Specific timbers (e.g., fir and spruce) suitable for pulp, rayon and newsprint.
• Minor forest products: tanning material, honey, dyes, essential oils, fodder and grasses.
• Exportable forest goods (teak, rosewood, paper products, gums and seeds) earning foreign exchange.
• Revenue from forest leases and employment opportunities linked to forest industries and management.

Forest Policy of India

India was among the first countries to adopt a national forest policy. The forest policy was formulated in 1952 and revised in 1988. The key objectives of the revised forest policy of 1988 included:

• Preservation of ecological balance and conservation of the country's natural heritage.
• Control of soil erosion, prevention of denudation in catchment areas, and prevention of extension of sand dunes in north-west deserts and along coasts.
• Meeting the basic requirements of rural and tribal populations for fuelwood, fodder and minor forest produce.
• Optimising utilisation of forestry products and increasing forest productivity through afforestation.
• Increasing overall forest cover by afforestation and reforestation programmes.
• Involving local communities and people's participation in forest conservation and management.

The Forest (Conservation) Act, 1980 was amended in and around 1988 to strengthen protection against deforestation and to regulate diversion of forest land for non-forest purposes; penalties for violations were enhanced. To prevent and control forest fires, a Modern Forest Fire Control Project was started in 1984 with assistance from the UNDP.

Afforestation Programmes

Various schemes have been undertaken to increase, preserve and maintain forest cover and to conserve fragile ecosystems such as hill slopes, catchment areas and canal banks. Major approaches include:

• Social forestry to produce fuelwood, fodder, fruit, fibre and fertiliser (the "5F") outside reserved forests and on community or degraded lands.
• Block plantations, strip plantations and farm forestry promoted under central and state plans.
• Creation of a National Wasteland Development Board to reclaim wastelands through afforestation with people's participation.
• Decentralised people's nurseries (begun in 1986-87) to encourage seedling production for local plantations.
• Research to improve planting stock and silvicultural techniques, and programmes to plant fast-growing species to meet fuelwood and fodder needs of rural communities.

Social Forestry - Objectives

Social forestry was given emphasis from the Sixth Plan onwards with the objective of meeting local needs without destroying natural forests. India's National Commission on Agriculture (1976) outlined the objectives of social forestry:

• To provide fuelwood and thus free cowdung for use as manure.
• To increase fruit production and add to potential food resources.
• To help conservation of soil and prevent further deterioration of soil fertility.
• To create shelterbelts around agricultural fields and improve productivity.
• To provide leaf fodder for cattle and reduce grazing pressure on reserved forests.
• To provide shade and ornamental trees for landscape improvement.
• To provide small timber and poles for agricultural implements, house construction and fencing.
• To promote tree-consciousness and love of trees among people.
• To popularise planting and tending of trees in farms, villages and public lands for their aesthetic, economic and protective value.

Relation Between Social Forestry and Environment

Social forestry is closely linked to environmental improvement and socio-economic upliftment. When implemented effectively and extensively, social forestry can generate several environmental benefits, including improved hydrological balance, better soil physical properties for infiltration and retention, replenishment of groundwater tables, reduction of surface runoff and sedimentation of reservoirs and streams, carbon recycling, and creation of favourable microclimates conducive to higher agricultural productivity.

Key environmental components addressed through social forestry include:

• Protection and afforestation of degraded forests near habitations.
• Creation of village woodlands on community lands and government wastelands.
• Block plantations in tank beds and foreshore lands.
• Agroforestry on marginal and sub-marginal farmlands.
• Tree planting along homesteads, field boundaries and diffused planting within fields, especially in arid and semi-arid zones.
• Pasture and silvi-pasture development.
• Urban and industrial tree planting for aesthetics, air purification and noise control.
• Control of water and wind erosion using shelterbelts, green belts and strip plantations along roadsides, canal banks and railway lines.

Successfully carried out, these programmes can meet rural needs for fuel, fodder, fibre and small timber while enhancing ecological security and protecting soil, water and air quality.

Problem Areas and Challenges in Social Forestry

While social forestry opens avenues for people's participation in forestry management, its success depends on addressing several problem areas:

• Stopping illicit felling and illegal extraction of forest produce.
• Controlling grazing pressure to allow regeneration.
• Managing productive forests for sustained yield and meeting both economic and ecological objectives.
• Protecting wildlife and integrating wildlife conservation with forestry plans.
• Rehabilitation of degraded forests and soils.
• Soil and water conservation measures linked to afforestation.
• Designing and implementing afforestation programmes with meaningful community participation.

Conclusion

Vegetation types in India reflect the wide climatic, altitudinal and soil variations across the country. Each forest type has characteristic structure, species composition and economic uses, while also playing a vital role in ecological stability. Sustainable management - combining conservation of natural forests with planned afforestation, social forestry and community participation - is essential to restore forest cover, meet local needs and maintain environmental services such as soil conservation, water regulation and climate moderation.