This MCQ module is based on: Tropical Forest Types — Evergreen, Deciduous & Thorn
TOPIC 12 OF 17
Tropical Forest Types — Evergreen, Deciduous & Thorn
🎓 Class 11
Social Science
CBSE
Theory
Ch 5 — Natural Vegetation
⏱ ~28 min
🌐 Language: [gtranslate]
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Chapter 5 · Natural Vegetation — Forest Types & the Tropical Forests of India
Have you ever wondered why a wild mango tree in a Western Ghats forest looks utterly different from the same species growing in your village backyard? Why a Rajasthan landscape gives birth to thorny kikar while the slopes of Kerala bristle with towering rosewood? India is a botanical museum — its tropical evergreens, deciduous monsoon forests and thorn scrubs together hold one of the planet's richest plant assemblages. This part untangles the difference between natural and planted vegetation, the four climatic-and-edaphic factors that shape it, and the three great families of tropical forests of India.
5.1 Natural vs. Planted Vegetation — Reading the Difference
Have you ever been to a forest for a picnic? Or strolled through a mango, guava or coconut orchard close to your village? The same mango tree may grow wild in a Western Ghats forest and in your school garden — but the two are not the same kind of vegetation. The garden tree is planted, watered and pruned by humans; the forest tree has fought for its place in a community of plants over centuries.
📖 Core Definition
Natural vegetation? refers to a plant community that has been left undisturbed by humans over a long period of time, allowing each species to adjust itself to the prevailing climatic and soil conditions as fully as possible. Planted vegetation, in contrast, is selected, sown and maintained under human supervision.
India is genuinely a land of botanical diversity. The Himalayan heights wear a coat of temperate vegetation; the Western Ghats and the Andaman & Nicobar Islands shelter tropical rain forests; the deltaic regions are framed with tropical forests and mangroves; and the desert and semi-desert tracts of Rajasthan are famous for cacti?, thorny bushes and scrub. Depending on the variations in climate and soil, the vegetation of India shifts from one region to the next.
5.1.1 Why one species, two faces?
The same variety of plant can grow either as a wild forest tree or as a domesticated garden tree. The difference lies not in the species but in the conditions under which it grows: temperature, water, light, soil, and above all, the presence or absence of human intervention. Wild trees compete with neighbours for sunlight and nutrients; planted trees enjoy a tailor-made spot.
🌿 Quick Sketch
India's natural vegetation is so varied because the country sweeps from the equatorial zone (latitudinally) and from sea-level deltas to 8,000 m peaks (altitudinally). No two places have identical climate, soil and relief — and so no two places carry exactly the same forest.
5.2 Factors Affecting India's Vegetation
Why does a forest grow where it grows? The answer lies in the interplay of four broad sets of factors. Each one acts as a filter, allowing some species to thrive and quietly excluding others.
Climate
Temperature, rainfall, humidity, and the length of the growing season together decide which species can establish themselves. Evergreen forests need both heat and abundant moisture; thorn forests survive on heat alone with very little water.
Rainfall
Areas receiving more than 200 cm of annual rain support evergreen forests; 100–200 cm supports moist deciduous; 70–100 cm supports dry deciduous; and under 50 cm gives birth to thorn forests and scrub.
Soil
Soil type, depth, fertility and drainage decide what can root. Rich loamy soils carry teak and sal forests; sandy and saline soils carry only grasses or thorny scrub; lateritic soils support hardy evergreens.
Relief & Drainage
Slope and altitude control temperature and the speed of water runoff; well-drained slopes carry tall trees, while waterlogged deltas carry mangroves. Each 1,000 m climb in the Himalayas carries you to a fresh forest belt.
Activity 5.1 · LET'S EXPLORE — Map the Climate–Forest Link
- List the four rainfall belts in India: >200 cm, 100–200 cm, 70–100 cm and <50 cm.
- Beside each belt, write the dominant type of forest you would expect.
- Explain why a single species (say teak) shows up in two belts but is the dominant tree only in one.
Pointers: >200 cm = Tropical Evergreen and Semi-Evergreen forests (Western Ghats, NE India, A&N Islands); 100–200 cm = Moist Deciduous (Himalayan foothills, eastern Western Ghats, Odisha); 70–100 cm = Dry Deciduous (Peninsular interior, plains of UP and Bihar); <50 cm = Tropical Thorn (south-west Punjab, Haryana, Rajasthan, Gujarat). Teak is dominant in moist deciduous (100–200 cm) but appears as scattered trees in dry deciduous areas — proof that rainfall determines dominance, not mere presence.
5.3 Five Forest Groups of India
On the basis of common features such as the predominant kind of vegetation and the prevailing climatic regime, the forests of India can be classified into five groups:
| # | Forest Group | Approx. Annual Rainfall | Indicator Species |
|---|---|---|---|
| (i) | Tropical Evergreen and Semi-Evergreen Forests | >200 cm | Rosewood, mahogany, ebony, white cedar |
| (ii) | Tropical Deciduous Forests (Moist & Dry) | 70–200 cm | Teak, sal, sandalwood, shisham |
| (iii) | Tropical Thorn Forests | <50 cm | Babool, ber, khair, khejri, palms |
| (iv) | Montane Forests | Variable; altitudinal control | Oak, deodar, silver fir, rhododendron |
| (v) | Littoral and Swamp Forests | Coastal & deltaic | Sundari, palm, mangrove species |
This part covers the first three groups — the tropical forests. Montane and littoral/swamp forests are covered in Part 2; wildlife and biosphere reserves form Part 3.
Figure 5.A: Schematic vegetation map of India by forest type — based on NCERT Figure 5.2.
5.4 Tropical Evergreen and Semi-Evergreen Forests
Where do the tallest, densest and most luxuriant Indian forests grow? The answer is on the rain-drenched western slopes of the Western Ghats, in the hills of the north-eastern region, and across the Andaman and Nicobar Islands. These are the lands of the tropical evergreen? forests — warm, humid, and green throughout the year.
5.4.1 Where are they found?
- Western slope of the Western Ghats — Karnataka and Kerala in particular.
- Hills of the north-eastern region — Assam, Meghalaya, Arunachal Pradesh, Nagaland and adjoining areas.
- The Andaman and Nicobar Islands — moist island ecosystems.
5.4.2 The climatic recipe
These forests need warmth and humidity. They are restricted to areas with an annual precipitation of over 200 cm and a mean annual temperature above 22°C. With water and warmth available year-round, there is no climatic compulsion for trees to shed their leaves all at once.
5.4.3 Architecture of an evergreen forest
Tropical evergreen forests are well stratified — they grow in clear vertical layers. Closer to the ground are shrubs, creepers and short, structured trees; above them rise tall trees that reach heights of 60 m or more. There is no fixed time for shedding leaves, flowering or fruition; some species drop a few leaves while neighbours flush new ones, so the canopy appears green throughout the year. Important species include rosewood, mahogany, aini and ebony.
5.4.4 Semi-Evergreen variant
The semi-evergreen forests grow in the slightly less rainy parts of the same regions. They form a transition between true evergreens and moist deciduous forests, holding a mixture of evergreen and moist-deciduous trees. The under-growth of climbers gives them an evergreen appearance even where the upper canopy is partly deciduous. Main species are white cedar, hollock and kail.
⚠️ The British Imprint
The British were keenly aware of the economic value of Indian forests and started large-scale exploitation. The structure of forests was changed: oak forests in Garhwal and Kumaon were replaced by chir pine needed for railway sleepers; many areas were cleared for tea, rubber and coffee plantations; timber was used for construction because it acts as a heat insulator. Thus, the protectional use of forests was replaced by their commercial use.
5.5 Tropical Deciduous Forests — The Monsoon Forests
The most widespread forests in India are not the evergreens; they are the tropical deciduous forests?, also called the monsoon forests. They cover regions that receive rainfall between 70–200 cm. On the basis of available water, these forests are subdivided into moist and dry deciduous types.
5.5.1 Moist Deciduous Forests
Moist deciduous forests are found in regions that record 100–200 cm of annual rainfall. They grow:
- Along the foothills of the Himalayas in the north-eastern states.
- On the eastern slopes of the Western Ghats.
- Across Odisha.
Main species include teak, sal, shisham, hurra, mahua, amla, semul, kusum and sandalwood. Teak and sal between them anchor most of central and peninsular India's commercial timber economy.
5.5.2 Dry Deciduous Forests
Dry deciduous forests cover much vaster tracts of the country wherever rainfall ranges between 70–100 cm. On their wetter margins they merge into the moist deciduous, and on their drier margins they fade into the thorn forests. They occupy the rainier parts of the Peninsula and the plains of Uttar Pradesh and Bihar. In the higher-rainfall stretches of the Peninsular plateau and the northern plain, these forests show a parkland landscape — open stretches with teak and other trees scattered amid patches of grass.
As soon as the dry season sets in, the trees shed all their leaves and the forest looks like a vast grassland with naked trees — a sight that returns every winter and gives the deciduous forest its name. Common trees include tendu, palas, amaltas, bel, khair and axlewood. In the western and southern parts of Rajasthan, vegetation is very scanty due to low rainfall and overgrazing.
Tropical Evergreen
Dense, multi-layered. Trees up to 60 m tall, never fully leafless. Western Ghats, NE India, A&N Islands.
Moist Deciduous
Teak, sal, sandalwood. Sheds leaves once a year in the dry season. NE foothills, eastern Ghats, Odisha.
Dry Deciduous
Naked trees in dry season — looks like grassland. Tendu, palas, bel, khair. Peninsular interior, UP and Bihar plains.
Tropical Thorn
Babool, ber, khair, palms. Plants leafless most of the year. South-west Punjab, Haryana, Rajasthan, Gujarat.
Activity 5.2 · THINK ABOUT IT — Why "monsoon" forests?
- List two facts that justify the name "monsoon forest" for the deciduous group.
- Why does sandalwood from Karnataka belong to the moist deciduous category and not to the evergreen?
- If a region with 90 cm rainfall slowly receives less rain over 30 years, which forest type would replace its current cover?
Pointers: (1) These forests grow only where the south-west monsoon delivers 70–200 cm of rain, and they shed leaves in the rain-less dry season — both signatures of monsoon dependence. (2) Sandalwood thrives in the 100–200 cm belt with a defined dry season, so it is moist deciduous, not evergreen. (3) A drop from 90 to ~60 cm would push the area from dry deciduous toward the tropical thorn forest belt; teak and sal would give way to babool, ber and khair.
5.6 Tropical Thorn Forests
What grows where rain is scarce, soil is sandy, and the sun is unforgiving? Tropical thorn forests — the vegetation cover of India's semi-arid? tracts.
5.6.1 Where are they found?
Tropical thorn forests occur in areas that receive rainfall less than 50 cm. Their reach covers the semi-arid lands of:
- South-west Punjab
- Haryana
- Rajasthan
- Gujarat
- Madhya Pradesh
- Uttar Pradesh (drier western parts)
5.6.2 What the forest looks like
The thorn forest consists of a variety of grasses and shrubs. Plants stay leafless for most of the year; what one sees is essentially scrub vegetation, with thorny stems that store water and deter grazing animals. Important species include babool, ber, wild date palm, khair, neem, khejri and palas. Tussocky grass grows up to a height of 2 m as the under-growth.
🌵 Adapted for Drought
Plants of the thorn forest carry classic xerophytic adaptations: small or absent leaves, deep tap roots that reach deep groundwater, thick waxy stems that store moisture, and thorns instead of leaves to reduce transpiration loss. The khejri tree, sacred to the Bishnoi community of Rajasthan, can survive on virtually no rainfall for years at a stretch.
Figure 5.B: Rainfall belts and the dominant forest type they support — the higher the rain, the taller and denser the forest.
5.7 Putting It All Together — A Quick Reckoner
| Forest Type | Rainfall | Region | Key Species |
|---|---|---|---|
| Tropical Evergreen | >200 cm | Western Ghats (W. slope), NE Hills, A&N Islands | Rosewood, mahogany, aini, ebony |
| Semi-Evergreen | 200–220 cm (less rainy parts of evergreen belt) | Same belt as evergreen, drier fringes | White cedar, hollock, kail |
| Moist Deciduous | 100–200 cm | NE foothills of Himalayas, eastern slopes of Western Ghats, Odisha | Teak, sal, shisham, sandalwood, mahua |
| Dry Deciduous | 70–100 cm | Peninsular interior, UP & Bihar plains | Tendu, palas, amaltas, bel, khair, axlewood |
| Tropical Thorn | <50 cm | SW Punjab, Haryana, Rajasthan, Gujarat, MP, UP (W) | Babool, ber, khair, khejri, neem, palas |
Activity 5.3 · MAP IT — Identify Forests on India's Outline
- On an outline map of India, shade in three different colours: tropical evergreen (Western Ghats, NE region, A&N Islands), tropical deciduous (most of the Peninsular plateau and Gangetic plain) and tropical thorn (Rajasthan, Gujarat, SW Punjab, Haryana).
- Mark these locations specifically: Cherrapunji, Mawsynram, Coorg, Kanpur, Jaisalmer.
- Beside each, write the rainfall range and the forest type expected.
Pointers: Cherrapunji and Mawsynram both fall in the >200 cm zone — tropical evergreen. Coorg sits on the Western Ghats — also evergreen. Kanpur lies in the 70–100 cm belt — dry deciduous. Jaisalmer receives <10 cm — barely supports thorn forest at all; the area is dominated by sandy desert with scattered xerophytic shrubs.
📋
Competency-Based Questions — Tropical Forests of India
Case Study: Aarav is preparing a poster on India's tropical forests. He has these data points: Mawsynram receives 1,080 cm of rain a year; the Konkan coast receives 250 cm; Bhopal lies in a 100 cm belt; Kanpur in a 90 cm belt; Jaisalmer in a 9 cm belt. He is asked to assign the dominant forest type to each location and justify each choice.
Q1. Sandalwood is a typical species of:
L1 RememberAnswer: (B) — Sandalwood occurs in the moist deciduous (100–200 cm) forests, alongside teak, sal, shisham and mahua.
Q2. The Konkan coast (250 cm rainfall) on the western slope of the Western Ghats would primarily carry which forest type?
L3 ApplyAnswer: (C) — Annual rainfall above 200 cm and warm humid conditions on the western slope of the Western Ghats are precisely the climatic recipe for tropical evergreen forests dominated by rosewood, mahogany and ebony.
Q3. Aarav notices that Kanpur (90 cm) supports trees that shed all their leaves in the dry season — they look like a vast grassland in summer. The forest type is:
L4 AnalyseAnswer: (C) — The 70–100 cm rainfall belt and the parkland-like appearance with naked trees during the dry season are diagnostic of dry deciduous forests. Tendu, palas, bel and axlewood are the typical species here.
Q4. Match the species with its characteristic forest type:
L2 UnderstandAnswer: (A) — Khejri is the iconic xerophytic tree of Rajasthan's thorn forest. Sundari belongs to the mangroves; mahogany to evergreens; teak to moist deciduous.
HOT Q. Imagine you are a forest officer in eastern Rajasthan. The annual rainfall has increased from 35 cm to 65 cm over twenty years. Sketch a one-page plan describing: (i) which species would you encourage to plant, (ii) which existing thorn species are likely to decline, and (iii) what new economic opportunities might arise for local communities.
L6 CreateHint: A jump from 35 cm to 65 cm pushes the area from thorn forest territory into the lower edge of dry deciduous. (i) Encourage hardy deciduous species such as khair, axlewood, palas; consider sandalwood plots in the wettest pockets. (ii) Babool and pure khejri stands may face crowding from broadleaf colonisers; pure xerophytes will retreat. (iii) Opportunities: minor forest produce (tendu leaves, mahua flowers), beekeeping, fuelwood plantation, agro-forestry plots; new water availability also opens scope for community-based farm forestry.
⚖️ Assertion–Reason Questions — Forest Types & Their Climatic Triggers
Options:
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is NOT the correct explanation of A.
(C) A is true, but R is false.
(D) A is false, but R is true.
(A) Both A and R are true, and R is the correct explanation of A.
(B) Both A and R are true, but R is NOT the correct explanation of A.
(C) A is true, but R is false.
(D) A is false, but R is true.
Assertion (A): Tropical evergreen forests appear green throughout the year.
Reason (R): In these forests there is no fixed time for trees to shed leaves, flower or bear fruit, so the canopy never becomes simultaneously bare.
Answer: (A) — Both A and R are true, and R is the correct explanation. Year-round warmth and rainfall above 200 cm remove any compulsion for synchronised leaf-fall, so different individuals shed leaves at different times.
Assertion (A): Tropical deciduous forests are also called monsoon forests.
Reason (R): They grow in regions where the south-west monsoon delivers between 70 cm and 200 cm of rainfall and they shed leaves in the dry season that follows the rains.
Answer: (A) — Both A and R are true and R correctly explains A. The very rhythm of the deciduous forest — green in monsoon, leafless in dry season — depends entirely on the seasonal pulse of monsoon rainfall.
Assertion (A): The British altered the structure of Indian forests dramatically.
Reason (R): They replaced oak forests in Garhwal and Kumaon with chir pine to lay railway sleepers and converted forest tracts into tea, rubber and coffee plantations.
Answer: (A) — Both A and R are true, and R is the correct explanation. The shift from protectional to commercial use of forests under colonial rule is one of the deepest legacies in Indian forest management.
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Class 11 Geography — India: Physical Environment
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