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S.3 Geography Notes

Tropical Rain Forests or Equatorial Forests

Tropical rain forests are also known as Equatorial or selva forests.  

They occur only in regions close to the equator.

Equatorial regions support a luxuriant type of dense vegetation – the tropical rain forest because of the very heavy rainfall and the uniformly hot temperatures.   The great extent of hardwood forests is between the latitudes of 200N and 200S of the equator.

In tropical Africa, the rain forest covers much of the Congo basin and along the western coastline of the continent, another belt of rain forest vegetation occurs along the eastern coast of Madagascar, lowlands bordering the Gulf of Guinea from Sierra Leone in the west to Cameroon and Gabon in the east.  The Congo forest covers the whole basin drained by river Congo and its tributaries like rivers Ubangi and Kasai. It occupies the lowlands of Congo-Kinshasa (Democratic Republic of Congo) and Congo Republic.  Nigeria, Gabon, Cameroon, Democratic Republic of Congo, Cote D’ivoire and Ethiopia are the leading commercial timber producing countries.  

Equatorial forest (vegetation) is characterized by:

  • It comprises of a multitude of evergreen trees that yield tropical hard woods like Mahogany, Ebony, green heart, rose wood, Cabinet wood, ironwood, Dyewoods and Elgon olive due to enough water and nutrients. 
  • There are smaller palm trees, climbing plants like the lianas or rattan, epiphytic and parasitic plant that live on other plants. Under the trees grow a wide variety of creepers, ferns, orchids, lalang and herbaceous plants. 
  • Trees grow in three distinctive layers or canopies.  The first layer known as the under canopy grows up to about 10m high, the second layer known as the main canopy grows up to about 30m high while the third layer of the tallest trees called the "emergent" rises up to about 50m high due to the growth of trees at different intervals or age and sprawl to form canopies. 
  • The trees are heterogeneous in nature or trees grow in mixed stands or have a variety of plants growing profusingly due to ample water supply like palms and mahogany.
  • The trees are tall that grow to height of 60 meters due to competition for light.
  • Trees are straight and have big trunks due to ample water supply.
  • The trees have evergreen broad leaves throughout the year that allows evaporation and get rid of excess water.
  • There is little or no under growth because of the thick canopy of foliage preventing light from reaching the ground.
  • The trees have huge buttress roots. Buttress roots are thin triangular slabs of hard wood that spread out from the bases of their trunks to provide extra support.
  • Trees have a long gestation period to mature of about 30 years+.
  • The trees are umbrella shaped

Economic Value/Benefits

  • It has to the Development of the tourism industry due to the presence of fauna and flora which are tourists’ attractions.
  • The growing of perennial and annual crops (tropical and temperate crops) like coffee Banana, Sugarcane, tea, cocoa which cultivated extensively in West Africa – Ivory coast and Ghana; palm oil in Nigeria, Congo Republic, bananas, pineapples due to the presence of well drained fertile soils
  • It has encouraged Lumbering activities or harvesting or exploitation of forest resources on a large scale, charcoal burning and gathering of firewood.
  • It has promoted the Collection of fruits, nuts and roots from the forests

Outline the problems facing the people living in the equatorial areas

 

SAVANNAH VEGETATION

Savannah refers to wide range of plant communities ranging from unbroken treeless grassland to woodlands in which trees and shrubs form an almost continuous cover. It is found in the north and south of the tropical rain forests; north and southern Congo Basin, Sudan, some parts of Western Africa and East Africa.Savanna Vegetation is categorized into:

*    Savannah grassland,

*    Savannah woodland and dry bush and thicket or steppe savannah.

Savanna vegetation is characterized by;

  • The savanna vegetation varies with the amount of rainfall from wood land with long grass, through acacia woodland which has short grass and scattered trees, to open, short grasslands with thorny bushes in the semi- desert areas.
  • Trees and plants have adapted themselves to the savanna climate rhythm of long winter drought and short summer rain both trees and plants are therefore,deciduous in nature, shedding their leaves in the cool dry season to prevent excessive loss of water through transpiration and lying dominant during the long drought.
  • They have long roots or deep roots (like the acacia trees) to search for ground water or broad trunks (like bottle and baobabs trees) to store up excessive water for use during the dry season.
  • Trees are mostly hard gnarled, thorny and may exude gum.
  • Many trees are umbrella- shaped to shield their roots from the scorching heat and to expose only a narrow edge to strong trade winds that blow all the year round.
  • The grass is tall and coarse, growing 2 to 4 metres (6-12 feet) high. The elephant grass may attain a height of 15 metres.
  • The grass which grows in compact tuffs has long roots which reach deep down in search of water.
  • The appearance of the savannah vegetation changes with the season. It appears green and fresh in the rainy season but turns yellowish-brown and parched with the ensuring dry season.

Economic Value/Benefits

  • It has led to development of the tourism industry. Savannah grassland in particular is the home of wild animals like Lions, Giraffes and Zebra.
  • Livestock farming like Nomadic pastoralism and Beef cattle ranching
  • The Growing of annual crops mainly Sorghum, Millet, Maize, cassava, sweet
  • It has led to the development of Api- culture (Bee-keeping). Charcoal burning and gathering of firewood from savanna woodlands

Outline the problems facing the people living in the savanna areas

 

SEMI – DESERT VEGETATION or DECIDUOUS BUSHLAND AND THICKET or SCRUB VEGETATION and DESERT VEGETATION

Semi – desert vegetation is found the Sahel region.

The desert vegetation is found in the Sahara Desert, Kalahari and Namib deserts.

Semi-desert and desert vegetation are characterized by;

  • Most of the scrubs have long roots and are well spaced out to gather moisture and search for ground water.
  • Plants have a few or no leaves and the foliage is waxy, leathery, hairy or needle- shaped to reduce the loss of water through transpiration.
  • Other plants like cacti have thick succulent stems to store up water for long droughts.
  • The seeds of many species of grasses and herbs have thick, tough skins to protect them while they lie dormant. They germinate at once when their seeds are moistened by the next rain.
  • Pants are fast maturing and complete their life cycle in a short time like shrubs
  • Some of the plants are entirely leafless, with pricks or thorns.
  • The predominant vegetation in semi-desert area is Xerophytic or drought-resistant scrub. This includes the bulbous cacti, thorny bushes, long-rooted wiry grasses and scattered dwarf acacia.
  • The leaves are spiny and thorny which reduce transpiration or loss of water
  • Plants that exist in the deserts have highly specialized means of adapting themselves to the arid environment.

Economic Value/benefits

  • It has led to the development of the Tourism Industry.
  • Nomadic Pastoralism for example Bedouin, Tuaregs, Matheniko, Masai and Galla
  • The growing of drought resistant crops like millet, Sorghum in Sudan.
  • The primitive hunters and collectors like the Bushmen of Kalahari Desert.

Outline the problems facing the people living in the semi-desert and desert areas

 

Discussion

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