Natural Vegetation

Written and reviewed by Subhra Gupta, Humanities faculty at UniDrill (M.A. Sociology, University of Delhi · 7 years teaching Humanities). Based on NCERT Geography Class XI (India: Physical Environment), Chapter 5.

Is the mango tree in your garden "natural vegetation"?

Not quite. The same mango species may grow wild in a forest and also stand in your garden, but the garden tree was planted and is looked after by people. Natural vegetation is a plant community that has been left undisturbed for a long time, so that its species could adjust as fully as possible to the climate and soil of the place. In India that adjustment produces a remarkable range: temperate vegetation on the Himalayan heights, tropical rainforests in the Western Ghats and the Andaman and Nicobar Islands, mangroves in the deltas, and cacti, bushes and thorny plants in the deserts of Rajasthan.

The five forest types at a glance

Indian forests are grouped by predominant vegetation and climatic region into five types. Rainfall is the master key: more rain gives thicker, taller, greener forest.

Tropical evergreen and semi-evergreen forests

These grow in warm, humid areas. The forest is well stratified, meaning it has layers: shrubs and creepers close to the ground, short trees above them, then tall trees reaching 60 m or more. There is no fixed time when trees shed leaves, flower or fruit, so the forest looks green all year round.

The semi-evergreen forests grow in the less rainy parts of the same regions. They are a mixture of evergreen and moist deciduous trees, and climbers growing below give them an evergreen character.

Why evergreen forests stay green. With rain through most of the year and no cold or dry season to cause water stress, trees do not need to drop their leaves together. Each tree sheds and renews leaves at different times, so the canopy as a whole is never bare.

Colonial use of forests. The British saw the economic value of the forests and began large-scale exploitation, which changed their structure. Oak forests in Garhwal and Kumaon were replaced by pine (chir) that was needed for railway lines, and forests were cleared for tea, rubber and coffee plantations. Timber was also used in construction. The forests' protective use was thus replaced by commercial use.

Tropical deciduous forests

These are the most widespread forests of India and are also called monsoon forests. They grow in areas with 70 to 200 cm of rainfall and are divided by water availability into moist and dry types.

In the western and southern parts of Rajasthan the vegetation cover is very scanty because of low rainfall and overgrazing.

Pause and predict: why do the trees of the dry deciduous forest drop all their leaves when the dry season starts?

Check your answer: leaves lose water. Dropping them cuts the loss of water when little is available, and the tree waits for the monsoon to bring new leaves. This is why the forests are called monsoon forests.

Tropical thorn forests

Where rainfall is below 50 cm, vegetation turns into scrub. Plants stay leafless for most of the year, and the forest gives the impression of scrub, with a variety of grasses and shrubs. Tussocky grass grows up to 2 m as undergrowth. Thorns and few leaves are signs of adaptation to dryness.

Montane forests

In the mountains, the fall of temperature with height changes the natural vegetation in a pattern of belts. Mountain forests are of two types: northern and southern.

Alpine pastures are used for transhumance, the seasonal movement of herds, by tribes such as the Gujjars, Bakarwals, Bhotiyas and Gaddis. The southern slopes of the Himalayas have thicker vegetation than the drier north-facing slopes because of higher rainfall.

Southern mountain forests. These are found in the Western Ghats, the Vindhyas and the Nilgiris. They are near the tropics and only about 1,500 m above sea level, so the vegetation is temperate in the higher parts and sub-tropical in the lower parts of the Western Ghats, especially in Kerala, Tamil Nadu and Karnataka. The temperate forests of the Nilgiri, Anaimalai and Palani hills are called Sholas. Economically important trees are magnolia, laurel, cinchona and wattle. Similar forests exist in the Satpura and Maikal ranges.

Pause and predict: why does the Himalayan south-facing slope carry thicker forest than the north-facing slope?

Check your answer: the southern slopes catch more of the monsoon rain, and so they carry more moisture-loving vegetation. The north-facing slopes are drier.

Beyond the textbook. For the exam: the Himalayas show a succession of vegetation from tropical at the base to tundra at the top as altitude increases. In reality: climbing 1,000 m cools the air by roughly 6 to 6.5°C, which is why a short climb replaces tropical forest with oak, then conifers, then bare alpine meadow, as if you had travelled thousands of kilometres towards the pole. Why it matters: this is the same logic as the latitude zones in the world climate chapters, compressed into a few kilometres of height.

Littoral and swamp forests

India has many wetland habitats, of which about 70 per cent are areas under paddy. The total wetland area is 3.9 million hectares. Two sites, Chilika Lake (Odisha) and Keoladeo National Park (Bharatpur), are protected as water-fowl habitats under the Ramsar Convention on wetlands of international importance. The country's wetlands are grouped into eight categories.

Mangroves grow along coasts in salt marshes, tidal creeks, mud flats and estuaries. They contain salt-tolerant plants, are criss-crossed by creeks of stagnant water and tidal flows, and shelter a wide variety of birds. In India they spread over 4,992 sq. km, which is 7 per cent of the world's mangroves. They are best developed in the Andaman and Nicobar Islands and the Sunderbans of West Bengal, and are also important in the Mahanadi, Godavari and Krishna deltas. These forests are being encroached upon and need conservation.

Beyond the textbook. For the exam: mangroves are littoral and swamp forests of coasts, creeks and deltas. In reality: their tangled roots slow down waves and trap silt, so a belt of mangroves helps protect a coast from storm surges and erosion, and it is also a nursery for fish. Why it matters: it explains why mangrove loss is treated as a coastal-safety issue and not only as a loss of trees.

Conserving forests

Forests are linked with life and environment in many ways, so their conservation is vital. The Government of India adopted a forest policy in 1952, modified in 1988. The new policy stresses sustainable forest management, expanding the forest reserve while meeting the needs of local people.

Social forestry means the management and protection of forests and afforestation on barren lands to help environmental, social and rural development. The National Commission on Agriculture (1976) classified it into three categories.

Community forestry lets landless people take part in tree-raising and share in benefits that otherwise go only to landowners.

Forests and life. For many tribal communities the forest is a home and livelihood, giving food, fruits, honey, roots, materials for houses and for their arts. The textbook says their age-old knowledge can help develop forests and that they should be made growers of minor forest produce and encouraged to take part in conservation, rather than being treated only as collectors.

Two views. For the exam: tribal communities depend on the forest and should be partners in conservation. Another reading: scholars and policy makers debate how best to protect forests and wildlife, with some stressing strictly protected areas for species and others stressing community management that also secures livelihoods. The two positions are usually seen as needing balance rather than a single winner.

Beyond the textbook. For the exam: a goal of 33 per cent forest cover is the policy target. In reality: forest officials separate forest area (land recorded as forest in government records, whether or not it has trees) from forest cover (land that actually has tree canopy). The two figures differ, and the gap shows how much recorded forest land has lost its trees. Why it matters: this distinction is a question in the chapter's own exercise.

Wildlife

India holds 4 to 5 per cent of all known plant and animal species of the earth, because of the great variety of its ecosystems. Their habitat has been disturbed and numbers have fallen sharply. The reasons for decline are listed below.

The law. A comprehensive Wildlife Act was enacted in 1972. It gives the main legal framework for protecting wildlife. Its two main objectives are to protect endangered species listed in its schedules and to give legal support to conservation areas such as national parks, sanctuaries and closed areas. It was comprehensively amended in 1991 to make punishments more stringent and to protect specified plant species. The country has 107 national parks and 573 wildlife sanctuaries.

Biosphere reserves

A Biosphere Reserve is a unique and representative ecosystem of terrestrial and coastal areas that is internationally recognised under UNESCO's Man and Biosphere (MAB) Programme. There are 18 biosphere reserves in India, and twelve of them are recognised on the UNESCO World Network of Biosphere Reserves.

Beyond the textbook. For the exam: a biosphere reserve is an internationally recognised ecosystem under the MAB Programme with three objectives. In reality: these are conservation, sustainable development and logistic support, and reserves are usually planned in three zones: a protected core, a buffer around it and an outer transition area where people live and work. Why it matters: the zoning is what separates a biosphere reserve from a national park, which protects only its own area.

Exam traps

60-second revision

Where this chapter connects

• Previous: Climate supplies the rainfall and temperature zones that decide each forest type.
• Related: Biodiversity and Conservation covers biosphere reserves, hotspots and conservation at the world level.
• Back to basics: Structure and Physiography explains the Western Ghats, Himalayas, deltas and islands where these forests grow.