Notes of Ch 8 Human Environment Interactions: The tropical and subtropical regions| Class 7th Geography

Study Material and Notes of Ch 8 Human Environment Interactions: The tropical and subtropical regions Class 7th Geography

Topics in the Chapter

• Life in the Amazon Basin
• Climate 
• Rainforests
• People of the Rainforests
• Life in the Ganga-Brahmaputra Basin

Life in the Amazon Basin

• The river Amazon flows through the tropical region lies very close to the equator; between 10°N and 10°S.
→ It is referred to as the equatorial region.

• The place where a river flows into another body of water is called the river’s mouth.

• Numerous tributaries join the Amazon River to form the Amazon basin. 

• The river basin drains portions of Brazil, parts of Peru, Bolivia, Ecuador, Columbia and a small part of Venezuela.

Climate of Amazon Basin

• The Amazon Basin is characterized by hot and wet climate throughout the year as it is present on the equator.

• Both day and nights are almost equally hot and humid. 

• The skin feels sticky. 

• It rains almost everyday, that too without much warning. 

• The day temperatures are high with very high humidity. 
→ At night the temperature goes down but the humidity remains high.

Rainforests in Amazon Basin

• Thick forests grow due to heavy rains.
→ These forests are so thick that the dense roof created by leaves and branches does not allow the sunlight to reach the ground.

• The ground remains dark and damp which and only shade tolerant trees may grow here.
→ Orchids, bromeliads grow as plant parasites.

• The rainforest is rich in fauna.
→ Birds such as toucans, humming birds, bird of paradise are found. 
→ Animals like monkeys, sloth and ant-eating tapirs are found here.
→ Various species of reptiles and snakes such as Crocodiles, snakes, pythons, Anaconda and boa constrictor also thrive in these jungles.
→ Several species of fishes including the flesh-eating Piranha fish is also found in the river.

People of the Rainforests

• Men hunt and fish along the rivers, women take care of the crops.
→ As hunting and fishing are uncertain it is the women who keep their families alive by feeding them the vegetables they grow.

• People practice “slash and burn agriculture”.

• The staple food is manioc, also known as cassava that grows under the ground like the potato.
→ They mainly grow tapioca, pineapple and sweet potato.
→ They also eat queen ants and egg sacs.

• Cash crops like coffee, maize and cocoa are also grown.

• The rainforests provide a lot of wood for the houses.
→ Some families live in thatched houses shaped like beehives while other large apartment-like houses called “Maloca” with a steeply slanting roof.

• Life of the people of the Amazon basin is slowly changing.
→ Amazon highway made all parts of the rainforest accessible. 
→ Aircrafts and helicopters are also used for reaching various places. 
→ The indigenous population was pushed out from the area and forced to settle in new areas where they continued to practice their distinctive way of farming.

•  The developmental activities are leading to the gradual destruction of the biologically diverse rainforests.

Life in the Ganga-Brahmapura Basin

• The tributaries of rivers Ganga and Brahmaputra together form the Ganga-Brahmaputra basin in the Indian subcontinent.
→ The basin lies in the sub-tropical region that is situated between 10°N to 30°N latitudes.

• The tributaries of the River Ganga like the Ghaghra, the Son, the Chambal, the Gandak, the Kosi and the tributaries of Brahmaputra like Dibang River, Lohit River, Teesta, Manas drain it.

• Main features of the basin: The plains of the Ganga and the Brahmaputra, the mountains and the foothills of the Himalayas and the Sundarbans delta.


• The area is dominated by monsoon climate. 
→ The monsoon brings rains from mid-June to mid-September.

• The summers are hot and the winters cool.


• The basin area has varied topography.

• The mountain areas with steep slopes have inhospitable terrain therefore, less number of people in the mountain area.

• Agriculture is the main occupation of the people in the plains because soil is fertile.
→ The density of population of the plains is very high.

• Paddy is the main crop while other crops grown are wheat, maize, sorghum, gram, millets, jute and sugarcane.
→  Cash crops like sugarcane and jute are also grown.
→ In West Bengal and Assam tea is grown. 
→ Silk is produced through the cultivation of silk worms in parts of Bihar and Assam.
→ Crops are grown on terraces in the mountains and hills.


• The vegetation cover of the area varies according to the type of landforms.

• In the Ganga and Brahmaputra plain tropical deciduous trees grow, along with teak, sal and peepal.
→ Thick bamboo groves are common in the Brahmaputra plain.

• In parts of Uttarakhand, Sikkim and Arunachal Pradesh, coniferous trees like pine, deodar and fir can be seen because the climate is cool and the slopes are steep.


• Elephants, tigers, deer and monkeys are common. 

• The one-horned rhinoceros is found in the Brahmaputra plain. 

• In the delta area, Bengal tiger, crocodiles and alligator are found.

• The most popular varieties of the fish are the rohu, catla and hilsa. 

• Fish and rice is the staple diet of the people living in the area.

Towns and Cities

• The cities of Allahabad, Kanpur, Varanasi, Lucknow, Patna and Kolkata all with the population of
more than ten lakhs are located along the River Ganga.

• The wastewater from these towns and industries is discharged into the rivers which pollute the rivers.


• All the four ways of transport are well developed in the Ganga-Brahmaputra basin. 
→ In the plain areas the roadways and railways transport the people from one place to another. 
→ The waterways, is an effective means of transport particularly along the rivers. 
→ The plain area also has a large number of airports.

Tourism Centres

• Tourism is another important activity of the basin.

• Some important places are: Taj Mahal on the banks of River Yamuna in Agra, Buddhists stupas in Uttar Pradesh and Bihar etc.

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