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| Sunday, 13 March 2005 |
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Junior Observer |  |
| News Business Features Editorial
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Grasslands of the world
Plants play an important role in the survival of both man and animal. Today we will examine the vegetation in the world's grasslands where animals such as lions, elephants, leopards, bison, zebras, rhinos and giraffes roam.... Many interacting factors such as history, position, climate and local environment have had an impact on the present distribution of plant-life over the face of the Earth. Important local environment factors include the physical positioning of the area, the soil and mostly the climate. The humidity, or amount of moisture in the air, together with the sun's energy, are the prime factors for vegetation.
Other factors such as soil play an important part in the type of vegetation, but, man has modified vast areas for urban development and agriculture. There are ten major divisions based mainly on types of vegetation which are generally recognised. They are: Polar regions, mountains, pine forests, temperate forests, tropical forests, grasslands, deserts, oceanic islands, continental seas and oceans. Grasslands Forming a transition zone between forests and deserts, grasslands which are drier towards the deserts, become richer and more lush as they approach the forests. On these grassy plains which extend as far as the eye can see, the large herbivores have very few hiding places. Their best means of defence is to live in large herds, with sometimes more than one species joining together for protection. But some, like the rhino and cape buffalo roam alone or in pairs as they are able to fight predators because of their size, strength and ferocity (fierceness).
Two main divisions of grassland are recognised, situated in two-strip-like regions across the world: temperate grasslands (steppes) and tropical grasslands (savannahs). Temperate grasslands Also known as steppes, these are situated well inland. Their characteristics are a temperate climate with hot summers, cold winters and very low rainfall. This leads to vast areas of short grass such as the Steppes of Eurasia, the Prairies of North America, the Pampas of South America and the Lowlands of Australia.
The North American prairie spreads from Canada to Mexico, while the grasslands of Europe and Asia extend from Hungary to China bordered to the north by great forests of deciduous and conifer trees. The deserts of Central Asia form the southern border. In the temperate grasslands generally found in the middle of large continents, far from the oceans and seas, the rains are carried by seasonal wind and are limited to spring and early summer. The severity of the winter that comes immediately after such rainfall, completely stunts the growth of plants, already slowed down. In this climate, only strong grasses grow. These areas look like enormous seas of grass. Tropical grasslands
The constantly hot climate throughout the year is the main characteristic of the savannahs or tropical grasslands. The short period of torrential rain which usually floods the savannahs is followed by a long period of drought. In this region, the grass is tall, sometimes reaching a height of three metres. Flat-topped acacia trees which are thorny and on which giraffes thrive on, are typical of the area. This type of vegetation is found in Africa, India, Australia and South America. The African Savannah varies between vast areas of grass, bush and scattered trees. The number of trees gradually increases towards the Equator until they form wooded areas on the edges of the great equatorial forests. These are known as 'wooded' savannahs. The short rainy seasons, followed by long periods of drought, control plant-life in the grasslands in a particular way. Plant-life
There are various types of plants found in the grasslands of the world. The animals which inhabit the grasslands seem to be feeding on the same plants but in reality, they have their own particular plant food. For instance, giraffes eat the leaves at the very top of acacia trees while the gerenuk, (a graceful antelope with a very long neck, also called the giraffe antelope) eats the top leaves of high bushes which other antelopes cannot reach. The lower parts are stripped of leaves by animals such as dik-dik and pigmy antelope. Most ruminants feed on the abundant grasses. Among the plants found in the grasslands are the baobab, euphorbia, eucalyptus and acacias. The baobab, which is a native of Africa has been introduced into America, India and Australia. Its maximum height is around ten metres. An old baobab can measure nine to ten metres in diameter and has large twisted branches. Sometimes they sweep down to the ground giving the tree a very curious appearance.
The euphorbia which are widespread in Africa have a characteristic candelabrum (branched candle holder) shape. There are many species, most of which contain a white milky substance which is generally rather poisonous. The real green giant, the eucalyptus which can grow up to a height of one hundred metres, is originally from Australia and have been successfully introduced to the Mediterranean and other regions. |
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