Chapter 8 - Human Environment Interactions: The Tropical and Subtropical Region

• Humans live in almost all parts of the world and share the same basic needs of food, shelter and clothing.
• What we eat or wear depends on the environment around us.
• The most fertile regions in the world are the tropical and the sub-tropical regions.
• The Amazon Basin is in the tropical/equatorial region and is drained by the largest river in the world, the Amazon.
• The Ganga-Brahmaputra Basin is the largest sub-tropical region in Asia and number of people living here is more than anywhere else in the world.

Amazon Basin

• The Amazon River was discovered by Vicente Yanez Pinzon, a Spanish explorer.
• The tropical region lies very close to the equator; between 10°N and 10°S and therefore is referred to as the equatorial region. This is the region where the Amazon River flows in South America, starting from the mountains in the west to the Atlantic Ocean in the east.
• The place where the river flows into another water body, such as a sea or an ocean, is called the river's mouth.
• The Amazon is joined by many tributaries (small rivers that join the main river) that together make the huge area called the Amazon basin which covers parts of Brazil, Peru, Bolivia, Equador, Columbia, and Venezuela.
• The main river along with all its tributaries that drain an area forms a river basin.
• The Amazon Basin is the largest river basin in the world.

Climate

• The Amazon basin stretches along the equator so its climate is hot and wet all through the year.
• Days as well as nights are equally hot and humid.
• It rains almost every day and the day temperatures are high with high humidity while night temperatures are low but the humidity remains high.

 

Flora and Fauna

• Because of the heavy rains, thick forests grow and a roof made by leaves and branches is created that is so dense that sunlight cannot penetrate and reach the forest floor.
• Since the ground is always dark and damp only shade-tolerant or parasite plants such as orchids and bromeliads grow here. Bromeliads are special plants that store water in their leaves and these pockets of water are used by animals like frogs for laying eggs.
• The rainforest is rich in fauna with birds like toucans, humming birds, and birds of paradise that make loud noises and have brightly coloured plumage and over-sized beaks for eating.
• Animals like monkeys, sloths, crocodiles, ant-eating tapirs and reptiles like anacondas, boa constrictor, snakes and pythons are also found here.
• The forest is also home to thousands of species of insects and hundreds of species of fish including the flesh-eating Piranha.

 

People

• People grow most of their food in small areas after clearing the trees there.
• Men mostly hunt and fish along the river and women take care of the crops.
• Women grow and use fruits and vegetables like tapioca, pineapple and sweet potato to feed their families since hunting and fishing are uncertain.
• The main type of agriculture practiced here is 'slash and burn'; a way of cultivating land where farmers clear a piece of land by slashing or cutting down trees and bushes. These are then burnt, which releases the nutrients into the soil. Now crops are grown in this cleared field for a few years. After repeatedly using the patch of land, the soil loses its nutrients. So it is abandoned. Then they clear another plot of land to plant. In some time, young trees grow in the land and the soil fertility is restored enabling people to return and cultivate it again.
• Manioc or cassava which is an under-ground vegetable is the staple diet of people living here.
• People here also eat queen ants and egg sacs and grow cash crops like coffee, maize and cocoa.
• The rainforest provides a lot of wood to build houses. They can be
  • thatched houses shaped like beehives
  • apartment like houses (called 'Maloca') with steeply slanting roofs
• The construction of the Trans-Amazon highway has eased transportation in the region and removed the dependency on the river to travel to the heart of the basin.
• Airplanes and helicopters are also used for transportation.
• Modern development activities such as construction are destroying the rainforests and large areas of the rainforests are disappearing every year.
• As more and more trees are cut down, the top soil in the region gets washed away by the rains and the land becomes infertile (turns barren).

Ganga-Brahmaputra Basin

• The Ganga-Brahmaputra basin, in the Indian subcontinent, is formed by the tributaries of river Ganga and Brahmaputra together.
• It lies in the sub-tropical region, between 10°N and 30°N latitudes and is drained by the tributaries of the Ganga including the Ghagra, the Son, the Kosi, the Gandak, and the tributaries of the Brahmaputra.
• The main features of this basin include the plains of the Ganga and the Brahmaputra, the mountains and the foothills of the Himalayas and the Sundarbans delta.
• Many ox- bow lakes are found in this region.
• The Ganga-Brahmaputra plain has several big cities, like Allahabad, Kanpur, Varanasi, Lucknow, Patna and Kolkata, located along the River Ganga.
• The transport system in the basin is well developed. Railways and roadways connect important towns and villages and waterways connect towns that are on the banks of rivers.
• Kolkata is an important international port on the river Hooghly and there are also many airports in the plains.
• Tourism is a major activity in the plains.
• Important Tourism sites are the Taj Mahal on the banks of Yamuna in Agra, Allahabad on the confluence (meeting) of rivers Ganga and Yamuna, Buddhist stupas in Uttar Pradesh and Bihar, Imamabara in Lucknow, Kaziranga and Manas wildlife sanctuaries in Assam and the tribal villages in Arunachal Pradesh.

Climate

• The area is dominated by monsoon climate hence it rains from mid-June to mid-September.
• Summers are hot and winters are cool.

 

Flora and Fauna

• The vegetation in different areas of the basin differs depending on the types of landform.
• The Ganga and Brahmaputra plains are covered with tropical deciduous trees and trees such as teak, sal and peepal.
• Thick bamaboo groves are present in the Brahmaputra plain and the delta is covered with mangrove forests.
• Due to the cool climate and steep slopes, coniferous trees like pine, deodar, and fir are found in Uttarakhand, Sikkim and Arunachal Pradesh.
• Elephants, monkeys, tigers, deer, crocodiles and alligators are commonly found all across the basin.
• The one-horned rhinoceros is found in the Brahmaputra plain and the Royal Bengal tiger is found in the Sundarbans delta.
• A lot of aquatic life is found in the fresh river waters, lakes, and in the Bay of Bengal.
• The most popular varieties of fish found are rohu, catla and hilsa.
• A variety of dolphin is found in the fresh waters of River Ganga and River Brahmaputra. Their presence is an indication of the health of the river.

 

People

• The topography of the basin area is varied and the distribution of population in different areas depends highly on the types of environment in those areas.
• Mountain areas have steep slopes and rough terrain so very few people live there.
  • Terrace farming is done on hilly or mountainous terrain by creating flat surfaces on steep slopes. Crops are grown in these flat surfaces.
• The plain is the most suitable area for habitation.
  • land is flat and the soil is fertile making its population density very high.
  • Agriculture is the main occupation of the people living in these areas.
  • Rice paddy is the main crop of these regions because it rains a lot in these regions and growing rice requires a lot of water.
  • Wheat, sorghum, gram, millets, maize, and cash crops like sugarcane and jute are also grown here.
• There are plantations of bananas in the plains, tea plantations in West Bengal and Assam and cultivation of silk worms for silk in Bihar and Assam.
• Fish and rice is the staple diet of the people living in the areas near water bodies.