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Topic (2) Environment and Ecology
Sub Topic 1: Ecological characteristics of terrain, monsoon climate, and vegetation
A look at the physical map of the Indian subcontinent shows that the area can be divided into three wellmarked geoecological regions each having distinguishing character. These are (a) the central and
southern uplands of Indian peninsula lying to the south of the plains of the Indus and Ganges river systems;
(b) the northern mountain system comprising the Himalayan ranges and their extensions into Baluchistan in
the west and Burma in the east; and (c) the Indo-Gangetic alluvial lowland between the peninsular India
and Himalaya (Fig. 1 in Map Gallery)
The Peninsular India
The surface of Peninsular India is made up of plateaus seldom rising more than 2,000 feet. Several hills
rise from the plateau surface to heights of more than 3,000 feet and in the south the Nilgiri Hills rise to an
elevation of more than 8,000 feet. To the west of the plateau are Western Ghats, an unbroken chain of
hill-ranges extending south of Malabar. On the eastern side of the peninsula are the broken and
discontinuous line of hilly country, called the Eastern Ghats. The northernmost part of the peninsular
highlands is formed by the Aravalli Range which terminates south of Delhi. To the northeast the Chota
Nagpur Plateau of Bihar forms the eastern extremity of the peninsular highlands. The island of Sri Lanka
comprising complex hill land with broad coastal lowland has many characteristics similar to the uplands of
Peninsular India.
Geologically, the peninsula is an ancient plateau exposed for long ages to denudation and approaching
peneplanation. Its mountains are of relict type which have escaped weathering and removal. It is an area of
ancient rocks of diverse origin. Over these ancient rocks lie extensive sheets of horizontally bedded lavas
of the Deccan Trap. The peninsula represents a stable block of the earth’s crust which has remained
unaffected by mountain building movements since the close of the Pre-Cambrian era. It has experienced
block faulting which has sunk some areas down relative to others. Along the coastal regions there were
marine transgressions which have laid sedimentary beds.
The principal mountains of Peninsular India are the Western and Eastern Ghats, Vindhyas, Satpuras, and
the Aravallis. The Western Ghats, also known as Sahyadri, has an average elevation of about 4,000 feet,
and forms a well marked feature along the west coast of India from the Tapti Valley to Cape Comorin, a
distance nearly 1,000 miles. The western slopes are steeper and precipitous. The major rivers of peninsular
India (Godavari, Krishna,and Cauvery) rise in the Western Ghats and flow eastward to into the Bay of
Bengal. In the north, the Western Ghats consist of flat-topped ridges of resistant Deccan Traps where the
headwaters of Godavari, Bhima and Krishna rivers are located. Tapti and Godavari are separated by the
Satmala ridge, while the Mahadeo ridge lies between the Bhima and Krishna rivers. Mahabaleswar, a hill
station, is located near the source of the Krishna river. The southern section of the Western Ghats lies 30 to
50 miles from the coast. To the south of the Nilgiri hills is the Palghat Gap in the mountains linking the
coastal plain of Kerala with plains of southern Tamil Nadu. The Karnataka and Kerala parts of the Western
Ghats have large plantations of tea, coffee, cinchona, cardamom, while the coastal plain grows much black
pepper, coconut and cashew.
The Eastern Ghats form a series of detached hill ranges extending from Orissa through the coastal regions
of Andhra to Nilgiri in Tamil Nadu.
The Vindhyas form a fairly continuous group of hill ranges extending from southern Bihar to Gujarat. The
majority of the ranges are composed of sandstones and quartzite relics of the old mountains. Satpura
range runs parallel to the Vindhyas and separates the Narmada and Tapti valleys. Satpura encloses
several flat-topped lava plateaus.
The Aravalli Range, the oldest mountains in the Indian subcontinent, extends southwest to northeast
across Rajasthan separating the arid semi-desert of the Bikaner, Jodhpur, and Jaisalmer area on the west
from the more fertile region of Udaipur and Jaipur on the east. The small detached quartzite ridges near
Delhi are the northernmost part of the Aravalli mountains.
Centuries ago, southern part of Peninsular India was the center of old Hindu empires and a civilization, that
in many pockets, never fell under the control or influence of the Islamic conquerors from the Northwest
Frontier or their descendants, who conquered most of India. This is a land of Dravidian temples, old towns
where fresh spices perfume the evening air, tropical beaches, and shaded inland waterways. Though
predominantly Hindu, it remains a successfully polyglot region spiritually and linguistically. Strong and
growing Christian churches were established well in advance of the arrival of foreign missionaries .
According to history that slips into legend, St. Thomas the Apostle brought Christianity to India in the first
century, long before most Europeans practiced the new faith. Jewish settlements sprang up too. The British
Empire in India began here in the 17th century, with the establishment of a trading post in Madras, now
renamed Chennai.
The Himalaya
The second ecological region, the mountainous area of the Himalaya comprises a series of several more
or less parallel ranges intersected by enormous steep-sided valleys and gorges. Their width is between 100
and 250 miles, comprising many minor ranges, and the length of the central axial range, the Great
Himalaya is about 1500 miles. The Great Himalaya and associated ranges form one of the most formidable
topographic barriers to communications in the world. Although crossed by numerous caravan routes, the
highest passes are nearly three miles in height; new highways now pierce the mountain wall from Tibet to
Nepal, and Sinkiang to Pakistan. The mountains are continued to the west in Pakistan and Afghanistan. In
Afghanistan the Hindu Kush mountains comprise a complex rugged region close to the borders of Republic
of Tajikistan. South of the Hindu Kush is the narrow alluvial plain of Kabul River, in which the city of Kabul,
the capital of Afghanistan is located. Beyond this, to the south, lies the complex mountainous region of
Hazara. The famous Khyber Pass (3,450 feet) in the mountains provides the route between the city of
Kabul and the plains of Pakistan.
Geologically, this is a region of folded and overthrust mountain chains of recent origin. Its rivers are youthful
and are actively eroding their beds in their precipitous courses and carving out deep and steep-sided
gorges. It is predominantly a region in which sediments laid down in a vast geosyncline continously from
the Cambrian to early Tertiary have been compressed, overthrust and elevated into dry land only since the
end of the Mesozoic times. The core of the mountains is composed of granitic intrusions of presumably
Tertiary age. The southern fringe of the mountains bordering the plains consists of fresh-water and
estuarine deposits of the Mio-Pliocene age derived largely from the erosion of the rising Himalaya. The
area has undergone earth movements of stupendous magnitude. Its strata are marked by complex folds,
reverse faults, overthrusts and nappes of great dimensions. These movements have not completely died
down, for this region is still unstable and is frequently visited by earthquakes of varying intensities. The last
major earthquake was on October 8, 2005 in Pakistani-controlled Kashmir which killed 73,338 people,
seriously injured 69,000 and left an estimated 2.5 million homeless.
The Himalaya is generally divided into four zones: (1) the foothills, (2) the middle Himalayan ranges. (3) the
Great Himalaya, and (4) the trans-Himalayan zone north of the Great Himalaya. To the west in Pakistan the
mountains are called Safed Koh Range along the Afghan border, Sulaiman Range, Margala hills and the
Salt Range. The Sulaiman Range runs from the Gumal river to Quetta in a large loop. South of Quetta is
the Kirthar Range which forms the boundary between Sind and Baluchistan. To the west of Kirthar is the
Makran Range which turns westward in a broad curve into southern Iran. In eastern part of the
subcontinent the Himalaya turns sharply to the south and forms a conspicuous arc along the India/Burma
border. The ranges continue forming the Andaman and Nicobar Islands and the Indonesian archipelago.
The Indo-Gangetic Plain
The third ecological division, the great alluvial plain of the Indus, Ganges, and Brahmaputra, stretches from
the Indus delta in Pakistan in a contiguous belt across northern India to the Ganges-Brahmaputra delta in
Bangladesh. This region is made up of layers of sands, clays and organic debris of very recent date
(pleistocene and recent) filling up a deep depression between the peninsula and the Himalaya. The plains
owe their origin to sag in the crust of the earth, probably formed contemporaneously with the uplift of the
Himalaya. This sag or depression was filled up by sediments derived from both sides, especially from the
Himalaya which are actively being eroded by the many rivers traversing the ranges.
The Indus and the Brahmaputra rise within a short distance of each other from the same mountain knot in
the neighborhood of the Manasarowar Lakes (14,000 feet) and flow along the northern limits of the
Himalaya, the one to the northwest and the other to the southeast and east. Both rivers break through the
mountains in profound gorges and issue on to the plains. The Brahmaputra bends back westward along the
foot of the Himalaya for some distance and joins the chief spill channel of the Ganges. The two rivers unite
to form the Padma in Bangladesh. The Ganges also rises in the Himalaya and flows eastward. Its main
tributary is the Jamuna. The chief affluents on the left bank of the Ganges are Gogra, Gandak, and Kosi.
The Indus flows along the structural trough between Kailas and Ladakh ranges for 180 miles; it then cuts
across the Ladakh range for another 300 miles and continues its course northwestwards for another 100
miles. At Bunji it pierces the Ladakh range for the third time in a 17,000-feet gorge, and heads for the lofty
peak of Nanga Parbat; and winds across Gilgit and Swat before emerging on the plains at Attock. The total
length of the Indus is 1,800 miles and the area of the basin is about 373,000 square miles. The Jhelum,
Chenab, Ravi, Beas and Sutlej are major tributaries of the Indus.
The Indo-Gangetic plain is of great historic and economic importance; it has been the principal theatre of
Indian history and its cultivated land supports bulk of the population of India, Pakistan and Bangladesh.
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Box: Field Report - Change Comes to a Village in Sunderbans Tide Country
For the boatmen (majhi) of the Ganges delta life ebbs and flows with the rhythms of the tide country. They
ferry back and forth from the village ghat. Hemmed in on all sides by the swirling waters surrounding the
delta, Rakhalpur is a village on the island of L-Plot in the Patharpratima block. For the boatmen life has
hardly been easy. There are many things they have to keep in mind – the timing of the tides, the possibility
of storms and how much load their vessels is carrying. And it is boatmen that the people of the village
depend on for survival.
From the mainland, Rakhalpur is about one and a half hours by bhutbhuti, the onomatopoetic name given
to the motorized boats of the Sunderbans. The boats serve as a lifeline, bringing in supplies, medicines and
other essentials to the island. But even in this heart of the tide country, life changed swiftly in spring of
2005. Take for example the single lamp post that stands at the head of the ghat. It runs on solar power and
every evening from dusk to idnight, throws a circle of light on the gloomy waters, helping boatmen to row
their dinghies safely to and fro. Miles away from the reach of main grid power because of the rivers
separating them, Rakhalpur is part of a grand plan that aims to bring alternative energy to all 53 inhabited
islands of the Sunderbans by 2010. Once completed, it will be an international demonstration project with
the highest concentration of renewable energy users in the world in an off-grid area. Each island will have
its own rural energy society, which will settle the all-important matter of tariff and handle distribution of
power at the micro-level.
At Rakhalpur, which got solar power in mid-April 2005, the benefits are already becoming apparent. The
traditional village economy used to draw upon agriculture and on breeding livestock and catching meen
(tiger-prawn hatchlings), for subsistence. But now, with uniterrupted solar lighting in over 50 shops, the
Rakhalpur market has become the center of new activity. The village has one of the biggest markets on the
island, and brighter lights everu evening mean more curious people, more hours of business – and of
course, better trade.
The local village council chief (panchayat pradhan) feels that the ancillary benefits of the project are just
round the corner. The village will soon procure machines to de-husk rice and grind spices, and plans are
afoot to set up a photocopier in the market. The local carpenters can look forward to electric tools to
improve their craft. Telephone booths and fridges dot the shopfronts and there is an increased clamor for
cable TV connections. Starry-eyed villagers also hope that video parlors will soon run late into the night.
No one knows how the village has changed better than a local resident, who has spent over 30 years of her
life in Rakhalpur. “Earlier the village would get flooded almost every year in the monsoons. There were no
roads and doctors never came here,” she remembers. But then she donated the huge plot of land on which
the solar plant has been set up. And resourceful villagers are already making full use of it – a local young
man wants to utilize the refrigeration facilities at the plant to make ice lollies, which go by the name of
‘Pepsi’ locally and have huge market in the summer months. But for boatmen, all that matters right now is
the light that stands on the ghat every evening to guide them home.
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Monsoon Climate
Everywhere in the Indian subcontinent the climate is dominated by the seasonal shift of winds - an inflow of
warm, water-saturated winds from the Indian Ocean in summer and an outflow of cold, dry winds from the
land in winter - which determines the seasonal rhythm of rains known as the monsoon. The region
alternates between the luxuriant green during the monsoon rain from mid-June to October and drab brown
of the dry season (March to May). The latitudinal range from south to north provides broad temperature
differences and the east-west extent affects the influence of the Arabian Sea and Bay of Bengal as a
source of moisture for rainfall. The northwestern part of India and Pakistan have least rainfall (varying from
less than 10 inches in the Thar Desert to 15 inches in some favored areas), and much of Deccan plateau of
Peninsular India receives only an average of 20 inches annually. The Indira Gandhi Canal, which taps the
water of the Sutlej, was completed in 1987 to irrigate 1.4 million hectares of cultivated land in the Thar
Desert of India along the India-Pakistan border. Rains in excess of 80 inches a year fall in the Ganges delta
of Bangladesh and eastern India, along the west coast of India, and in southwestern Sri Lanka.
The monsoon is characterized by the seasonal reversal of the wind system. During the summer monsoon
moist winds blow from the Arabian Sea and Bay of Bengal towards the landmass of the subcontinent. In the
winter season dry monsoon winds blow from land towards the Arabian Sea and Bay of Bengal.The
southwest or summer monsoon starts at the end of May and continues through October. It is the rainy
season. The northeast or winter monsoon lasts from December to March, which is generally dry season
over most of the subcontinent except along the Tamil Nadu coast and Sri Lanka, where the northeast winds
pick up moisture over the Bay of Bengal. Cyclonic storms from the Mediterranean traveling eastwards bring
winter rains in northwest India and Pakistan.
The seasonal reversal of the wind system is caused by changes in temperature and atmospheric pressure.
During the summer high temperatures over the subcontinent produces low pressure, and the winds move
from the relatively high pressure over the
Surrounding seas to the land bringing precipitation. During the winter months cold temperatures produce
high pressure, and the wind blows offshore towards the relatively low pressure over the surrounding seas.
Most of the rains in the subcontinent comes from the moist summer monsoon winds coming from the sea.
At the peak of the summer, nature seems to be frozen in time, holding its breath in anticipation. As the
Indian summer chugs on, painting everything with a pale, dusty palette; all is bronze and tan. A seesaw
between a parched, dried out existence and a hopefully wet future, adequately dehydrated, takes control of
India’s live, mind, and conversation. The temperature climbs and the collective Indian hope follows, taking it
as an omen, a premonition that the blazing heat can have but one final climactic ending, as in the past
centuries – the monsoon rain. Then it arrives. Settling the dust, flooding the rivers, making the peacocks
dance, the fish spawn, the trees green, and making India smile. A clap of thunder, a streak of lightning, jet
clouds rolling across the sky .. all herald the tempestuous rain showers that reach the plains and wooded
hillsides of India. Mother nature sheds her summery mantle to don an ebony cloak. The parched brown
earth, watered by manna from heaven, turns to a brilliant, verdant green. The monsoon is a mixed blessing:
whimsical, unpredictable and unmistakably Indian.
Natural Vegetation
Through centuries of settlement, clearing for agriculture, and unregulated grazing much of the original
forest cover of the subcontinent has been lost. Gross forest cover continues to decline in all the countries
of the subcontinent. Forest cover has declined 12 percent in India between 1973 and 1982. Bangladesh
has less than 15 for its area under forests. Tropical deciduous forests formed the original vegetation cover.
The use of forest products, biodiversity and sustainability of agricultural production are important in most of
the hilly areas of the subcontinent. Primary agricultural activities in the Himalaya and peninsular India are
based on crops and livestock, while forestry and forest resource management are secondary supporting
activities. Local people are dependent on forest resources in the hilly areas for fodder, fuelwood, food,
building materials, medicinal plants, and fertilizers. This strong dependency of agriculture and livestock on
forest resources is one of the main characteristics of rural production system in the subcontinent. The main
impacts of deforestation and forest degradation are soil erosion,compromise of the sustainability of
agricultural production systems, and diminishing biodiversity.