Ch-8 Tropical and Subtropical Regions

Part I - Tropical region: Amazon Basin
Lies in the equatorial region, at 10°N and 10°S of the Equator
Amazon river--> starts from the Andes Mountains of Peru, going eastwards and draining into the Atlantic Ocean. It has over 1,100 tributaries from the main river. It is the largest river basin in the world.
Areas covered--> Parts of Brazil, Peru, Bolivia, Ecuador, etc.
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Section I - Climate
Hot & wet climate, with the daytime being intolerable from the direct sunlight and high humidity. Nights are cooler but still humid.
Temperature range- 25°C to 30°C.
Annual rainfall- 250mm throughout the year
Rainfall type- convectional rainfall that Occurs mostly during the afternoons, hence it is called 4 o' clock rain.
Humidity is high because the cloud cover is more throughout the year.
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Section II - Natural vegetation and Wildlife
The amazon rainforest is also known as selvas.
They are called the lungs of the earth, as they take in carbon dioxide and release oxygen. 20% of oxygen is produced by the Amazon rainforest.
The hardwood trees are placed together with broad leaves, which form a canopy over the forest floor and block sunlight from entering the lower levels of the forest. Resulting in a damp, humid, and dark region
The soil is highly infertile and acidic, due to the large amount of rainfall, which washes the nutrients away.
Plants and animals have adapted to this harsh climate by methods-
--> Surviving on other plants rather than on the forest floor. Eg. Ferns, mosses, orchids,
--> Vines such as Lianas wrap around other trees for nutrients and survival.
--> Many plants have leaves with pointed tips which allow water to fall easily
--> Epiphytes - Plants that thrive on the upper branches of trees, taking nutrients from the air and water instead of the soil. Eg. lichens, ferns, mosses, etc.
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Commonly found species of plants-

Cacao
Palm
Rubber
Halsa
Cane
Cinchona
Carnauba palm trees
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Wildlife
Mammals--> Monkeys, Jaguars, Sloths, Pumas, Tapirs, etc.
Wildlife--> Pythons, species of birds, butterflies, frogs; crocodiles, etc.
Fishes--> over 2000, including species like piranhas, pirarucu, tambaqui, etc.
others--> Amazon rainforest Dolphins, Amazon manatee, etc.
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Adaptations
Monkeys like spider monkeys, have strong limbs which allow them to climb tree easily.
The flying frog has fully webbed feet at a flap of loose skin which allows them to glide around easily.
Three toed sloths have tan fur, while two toed sloths have brown fur, which allows excellent camouflaging.
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Section III - Life of the People
Tribes like Yanomami, Tikanu, Akuntsu, etc. Live here
Tribal people practice hunting, gathering, agricultural methods likes shifting agriculture or slash and burn agriculture
Shifting agriculture/slash and burning agriculture--> cutting and burning of trees and plants, then using their ashes in another plot of soil, to provide nutrients for growing crops.
Crops- yam, banana, beans, pineapple, sweet potato, etc.
Cash crops- cocoa, coffee, rubber, maize, etc.
Minerals and ores, such as iron, gold, copper, etc. Are abundantly found here, making mining an important industry in the region.
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Houses
People live in huts with thatched roofs shaped liked beehives.
Some houses are built on stilts to prevent flooding of the house.
Malocas--> Apartment-like houses with steep slanting roofs which allows water to flow down easily.
Materials used--> Wood, Mud, and Clay.
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Problems - deforestation
Large amounts of trees are being cut for more pastoral farming.
Implementations of mines for iron, gold, etc. have resulted in the cutting of trees.
Roads made for miners, farmers, and loggers mean more cutting of rainforest.
The trans-Amazonian highway has made the forest accessible to the outside world, which poses a threat to the natives of the rainforest.
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Section IV - Transport and Cities
The dense forests and swamps make it hard for roads to be constructed.
Rivers are the mot vital source of transportation, by using boats, rafts, etc.
The trans-Amazonian highway built in 1970 is transforming the lifestyle of the people. It connects the Atlantic port of Recife to Peru, and passes through significant towns.
--> Manaus, a rubber collection center with an international Airport.

--> Belém, located at the mouth of the amazon river, is a Great trading town and the primary port of the region.

Sub tropical region: Ganga-Brahmaputra Basin
This region lies 10°N and 30°N of the equator, just south of the Himalayas.
This basin includes the Ganga and Brahmaputra rivers' plains, the foothills of the Himalayas, and the Sundarbans.
Countries- Tibet, China, India, Bangladesh, and Bhutan.
States of India- Meghalaya, Uttarakhand, Uttar Pradesh, Bihar, Jharkhand, west Bengal, etc.
These plains form a large part of the Indo-Gangetic-Brahmaputra plains, which are very fertile by the alluvial deposits from the two rivers— Ganga and Brahmaputra.
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Ganga
Source of the river--> Gangotri Glacier
Formed by--> Two headstreams merging together at the Devprayag.
Flows eastwards after entering the Haridwar Plains, and is joined by Tributaries of Yamuna, Gomti, Son, etc.
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Brahmaputra
Source--> the Chemayungdung glacier near Mansarovar. It is called Tsangpo
Path--> Arunachal Pradesh ―> Assam ―> Bangladesh. Many tributaries of Lohit, Teesta, etc. Are joined in.
Together, Ganga and Brahmaputra meet and form the largest and most fertile Delta, which is the Sundarbans.
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Section I - Climate
The Ganga-Brahmaputra region has a monsoon type of climate, with hot summers, wet monsoons, and cold winters.
The southwest monsoon winds brings regular monsoons from June to September, with the Delta and The Brahmaputra Valley receiving intense rainfall, and becoming less at the Gangetic Valley.
This region received frequent tropical cyclones.
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Section II - Natural vegetation and Wildlife
Comprises of tropical deciduous forests, with plants like taek, bamboo, etc.
Brahmaputra plains--> thick bamboo groves are common.
in higher altitudes like Arunachal Pradesh, Sikkim, etc. Coniferous plants are commonly found.
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The Sundarbans
They have the largest mangrove forests in the world.
This delta has been declared as a UNESCO World Heritage Site.
Mangroves-
--> They can thrive both in saltwater and freshwater
--> They have complex salt filtration systems and root systems to withstand wave action.
--> They are also grown in waterlogged mud with low oxygen levels.
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Wildlife
Most of the wildlife is found at the Sundarbans or the Brahmaputra Valley.
Specialities- One-horned rhinoceros are found in the Brahmaputra Valley, Royal Bengal Tigers are found in the Sundarbans.
Other animals include elephants, alligators, jaguars, etc.
Fishes include a large variety of freshwater fishes, Hilsa, rohu, etc.
Variety of Dolphins locally known as Susu (wtf is that name)
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Section III - Life of the People
This land is the most suitable for habitation as the land is flat, and there are many resources available since the soil is also fertile, hence the population density is also high.
The main occupation is agriculture, since there are favourable climatic conditions, fertile alluvial soil deposited by the rivers, and an ample supply of water for the crops.
Crops-
-->Primary crop- Paddy
-->Maize, Wheat, Rice, Millets, sugarcane, etc.
-->Cash crops- Tea in assam, jute in west Bengal, and also silk in Bihar and Assam.
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Types of occupations-
Terrace farming- practiced on steeps hills by cutting terraces into them to create level area for crops.
Fishing- done in coastal regions
Transhumance- done in higher altitudes. Involves seasonally moving livestock between mountains and the low-land regions, under the supervision of herders.
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Industries Established-
Sugar, Textile, and Edible oils
New industries, like automobiles, chemicals, fertilizers, etc. Have also been constructed, and have provided employment to multiple people.
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Section IV - Transport and Cities
There is good rail, road, and air travel options due to the flat land of this region.
The rivers here are navigable, which has caused newer implementations on waterways.
River Hooghly- Kolkata is the important port.
The developed navigation system has facilitated the rapid development of various industries of trade, tourism, etc. in the area
This region has a lot of historic cities, industrial cites, and port towns
Port towns--> Agra, Haridwar, Varanasi, Delhi, Kolkata, etc.