Life in The Tropical and Subtropical Regions Chapter Notes - Footprints

The Amazon Basin

The Amazon Basin is the largest river basin in the world covering an area of about 7 million sq km. This basin, or Amazonia, is the world's largest equatorial rainforest wherein resides a wealth of life richer than anywhere else on Earth.

Location

• Located in South America, it extends between:
  • the Brazilian Highlands in the south and the Guiana Highland in the north
  • the Andes Mountains form its western boundary
  • the Atlantic Ocean is to the east
• River Amazon or Solimoes, rising in the snow-covered Andes, flows east into the Atlantic Ocean. It is the world's largest river in terms of water volume and the second longest river at about 6,400 km. The basin is drained by the river Amazon and its tributaries such as Madeira, Rio Negro, and Xingu.

Climate

• The Amazon basin, being in the equatorial region, receives the vertical rays of the Sun year-round.
• The climate is hot and wet throughout the year with average temperatures ranging between 25°C and 30°C.
• Annual rainfall exceeds 250 cm, with rain almost every day, typically in the afternoon.

Natural Vegetation

• The Amazon Basin is covered by dense, evergreen, tropical rainforests known as the selva.
• These forests are difficult to penetrate and have limited commercial value.
• They contain broadleaved hardwood trees such as mahogany, rubber, ebony, and rosewood, providing resources for construction and furniture making.

Wildlife

• The region is home to a wide variety of wildlife including monkeys, big cats, reptiles, and colorful birds.
• Endangered species due to persistent hunting.
• More than 2,000 fish species inhabit the region's waters.

Life of the People

• Tribal people inhabit the forest, practicing hunting, gathering, and fishing.
• Some engage in shifting cultivation, raising crops like manioc, yam, and cassava.
• Commercial activities include rubber tapping, mining, and agriculture.

In recent years, rapid deforestation in the Amazon Basin has led to the loss of biodiversity, emphasizing the need to curb this practice for the future's sake.

The Ganga-Brahmaputra Basin

• The Ganga-Brahmaputra Valley, situated in the subtropical region, is an exceptionally fertile riverine plain formed over millennia by sediment deposition from the Ganga and Brahmaputra rivers along with their tributaries.
• Extending across regions like Delhi, Uttar Pradesh, Uttarakhand, Bihar, Jharkhand, West Bengal, Assam, and Arunachal Pradesh in India, as well as parts of Nepal, Bhutan, Bangladesh, Tibet, and China, the basin is bordered by the Himalayas to the north, the Peninsular Plateau to the south, and the Purvanchal Hills to the east. It merges with the Indus Plain in the west.
• The valley experiences a monsoon climate with hot, dry summers and cool, dry winters, ideal for agriculture due to a well-defined rainy season brought by the southwest monsoon winds, resulting in ample rainfall, particularly in the delta region and the Brahmaputra Valley.
• The natural vegetation in the region includes tropical monsoon deciduous forests with trees like teak, sal, and mahua, bamboo in the Brahmaputra valley, and sundari trees in the deltaic tracts, adapted to saline and tidal conditions.
• Wildlife, concentrated in the Sundarbans region and parts of the Brahmaputra Valley, includes species such as elephants, rhinoceroses, tigers, deer, monkeys, various fish like rohu, catla, hilsa, crocodiles, alligators, Royal Bengal Tigers in the Sundarbans forest, and one-horned rhinos in the Brahmaputra plains.
• The Ganga-Brahmaputra Basin, a key agricultural region globally, supports crops like rice, jute, wheat, maize, millets, sugar cane, tea, oilseeds, and pulses through intensive farming practices, irrigation systems, and a variety of agricultural techniques leading to high yields per acre.
• In addition to agriculture, the region engages in commercial fishing, tea plantations in West Bengal and Assam, agro-based industries, and various small to medium-scale industrial activities, facilitated by a network of roads, railways, waterways, and airports.
• The densely populated region faces challenges of rapid urbanization, including issues like river pollution, slums, water and power shortages, crowded cities, housing deficits, and unemployment, necessitating efforts to restore the balance between human development and environmental conservation.