Natural Vegetation and Biogeography of India

Vegetation, flora and biogeography

Natural vegetation is the plant cover that grows without direct human help and has been left undisturbed for a long time. Flora means the plant species of a region, fauna its animals. Biogeography studies why living things are distributed the way they are – across climate zones, relief and history. India is one of the world's 17 megadiverse countries: with about 2.4 per cent of the world's land, it holds roughly 7–8 per cent of recorded species, including about 45,000 plant and over 1,00,000 animal species. It also contains parts of four of the world's 36 biodiversity hotspots: the Himalaya, the Indo-Burma region, the Western Ghats–Sri Lanka, and Sundaland (the Nicobar Islands).

What controls vegetation

• Rainfall is the single most important factor – the amount and the length of the dry season decide whether forest is evergreen, deciduous or thorny.
• Temperature and altitude – in the Himalaya, vegetation changes with height just as it does with latitude.
• Soil – mangroves on saline tidal mud, thorn scrub on sandy desert soils.
• Sunlight and relief – south-facing slopes of the Himalaya are warmer and support different forests from north-facing ones.

Forest cover: the numbers

According to the India State of Forest Report (ISFR) 2023, released in December 2024, India's forest cover is about 7.15 lakh sq km (21.76 per cent) of geographical area, and forest plus tree cover is about 25.17 per cent. Madhya Pradesh has the largest forest area, followed by Arunachal Pradesh and Chhattisgarh; Mizoram has the highest share of its area under forest. The National Forest Policy of 1988 aims for 33 per cent of area under forest or tree cover.

Major vegetation types of India

1. Tropical evergreen and semi-evergreen forests

• Where: rainfall over 200 cm with a short dry season – the western slopes of the Western Ghats, the north-east hills and the Andaman and Nicobar Islands.
• Features: dense, multi-layered, trees up to 60 m tall; no single season for shedding leaves, so they look green all year.
• Species: rosewood, mahogany, ebony, aini, cinchona, and rubber in plantations. Semi-evergreen forests in slightly drier margins mix in white cedar, hollock and kail.
• Fauna: elephants, lion-tailed macaque, hornbills, the one-horned rhinoceros in the north-eastern grasslands nearby.

2. Tropical deciduous (monsoon) forests

The most widespread forests of India.

• Moist deciduous (100–200 cm rain): the north-east foothills, the Shiwalik and Terai belt, Jharkhand, Odisha, Chhattisgarh and the eastern slopes of the Western Ghats. Main trees: teak, sal, shisham, bamboo, sandalwood, khair, mahua.
• Dry deciduous (70–100 cm rain): large parts of the peninsula and the Ganga plain; open forests of teak, sal, peepal and neem, often cleared for farming.
• Trees shed leaves for six to eight weeks in the dry summer to save water.

3. Tropical thorn forests and scrub

• Where: rainfall below 70 cm – Rajasthan, Gujarat, south-west Punjab and Haryana, the rain-shadow of the Deccan.
• Species: acacia, babool, khejri, ber, cactus and euphorbia – deep roots, thick fleshy stems and small or spiny leaves to cut water loss. The khejri is sacred to the Bishnoi community of Rajasthan.
• Fauna: the great Indian bustard, blackbuck, chinkara, Indian wild ass (Rann of Kachchh).

4. Montane (mountain) forests

Vegetation changes with height in the Himalaya:

In the Nilgiris, Anaimalai and Palani hills, montane forests above about 1,500 m are called sholas, patches of stunted evergreen forest set amid rolling grasslands.

5. Littoral and swamp (mangrove) forests

India has about 4,992 sq km of mangroves (ISFR 2023), roughly 3 per cent of the world's total. West Bengal's Sundarbans hold the largest share, followed by Gujarat and the Andaman and Nicobar Islands. Mangroves such as sundari (which gives the Sundarbans their name), *Rhizophora* and *Avicennia* grow in salty, waterlogged tidal mud, using stilt roots and breathing roots (pneumatophores). They protect the coast from cyclones and storm surges, are nurseries for fish, and store large amounts of blue carbon. The Royal Bengal tiger of the Sundarbans is adapted to swim. India launched the MISHTI scheme in 2023 to restore mangroves.

Biogeographic zones of India

The Wildlife Institute of India (Rodgers and Panwar) divides the country into 10 biogeographic zones:

1. Trans-Himalaya – cold desert of Ladakh and Lahaul–Spiti; snow leopard, Tibetan wild ass.
2. Himalaya – red panda, musk deer, Himalayan monal.
3. Desert – Thar and Kachchh.
4. Semi-arid – Punjab to Gujarat; the Asiatic lion of Gir.
5. Western Ghats – high endemism, especially amphibians.
6. Deccan Peninsula – the largest zone; tiger, gaur, sloth bear.
7. Gangetic Plain – swamp deer, Gangetic dolphin.
8. North-East – richest in species; hoolock gibbon.
9. Coasts – mangroves, turtles (Olive Ridley nesting at Gahirmatha).
10. Islands – Andaman and Nicobar, Lakshadweep; very high endemism such as the Nicobar megapode.

Threats and conservation

Threats include habitat loss to farms, mines, dams and roads; invasive species such as *Lantana camara* and *Prosopis juliflora*; forest fires; poaching; and climate change, which pushes alpine species upslope.

Conservation tools:

• Protected areas under the Wildlife (Protection) Act, 1972 – about 1,000+ protected areas (national parks, wildlife sanctuaries, conservation and community reserves) covering about 5.3 per cent of India.
• Project Tiger (1973) – India's tiger count was about 3,682 in 2022 (mean estimate), around 75 per cent of the world's wild tigers; there are now 58 tiger reserves (as of 2025).
• Project Elephant (1992), Project Cheetah (cheetahs from Namibia and South Africa in Kuno, Madhya Pradesh, from 2022), and the Great Indian Bustard recovery programme.
• Biosphere reserves – 18, of which 12 are in UNESCO's network; e.g. Nilgiri (India's first, 1986), Sundarbans, Gulf of Mannar, Nanda Devi.
• Ramsar sites – India has about 90+ wetlands of international importance, the highest number in Asia.
• Community efforts – the Chipko movement (1973), the Bishnoi tradition, sacred groves (*devrais, kavus, sarnas*), and Joint Forest Management.
• Green India Mission and compensatory afforestation (CAMPA).

Grasslands, wetlands and the value of ecosystems

Not all of India's natural vegetation is forest. Grasslands such as the Banni of Kachchh, the terai grasslands of Kaziranga and Dudhwa, the high-altitude bugyals of Uttarakhand and the shola grasslands of the Nilgiris support grazing herders and species like the rhino, swamp deer, Nilgiri tahr and the great Indian bustard. They have often been wrongly classed as "wasteland" and planted with trees, which harms the species that need open land. Wetlands – lakes, marshes, floodplains, mangroves and coral reefs – purify water, recharge groundwater, absorb floods and support fisheries; Chilika, Keoladeo and Loktak are among the best known Ramsar sites.

Ecosystems provide services worth far more than the timber they yield: forests hold soil, regulate rivers, store carbon and provide food, fodder, fuel and medicine to about 300 million forest-dependent people. The Forest Rights Act, 2006 recognises the rights of tribal and traditional forest dwellers, and the Forest (Conservation) Amendment Act, 2023, which changed which lands count as "forest", has been debated for its effect on protection.

Mains practice question

"Rainfall is the main determinant of India's natural vegetation." Examine this statement with suitable examples, and discuss the threats to India's forests. (250 words)

Answer framework

• Intro: forest cover data (ISFR 2023), megadiverse status.
• Rainfall link: evergreen (>200 cm), moist and dry deciduous, thorn (<70 cm).
• Other factors: altitude (montane), soil (mangroves).
• Threats: habitat loss, invasive species, fires, climate change.
• Conclusion: protected areas plus community participation.