Savanna Climate And Vegetation
Savana climate is also known as Sudan climate. It has distinct wet and dry seasons. It is a transitional type of climate which can be found in the region between equatorial rainforests and hot deserts of the subtropics.
Savanna Climate And Vegetation
Savana Climate has a distinct dry season which occurs in winter. All the rainfall in the region is concentrated during the summer. The long dry season causes many plants to die and streams to dry, which causes migration of animals.
- It is situated within the tropical latitudes on either side of the equator. It is well developed in Sudan, and hence the name, where there are distinct wet and dry seasons.
- In the northern hemisphere, this climate is found in Africa (African Sudan, East Africa), and South America (Llanos grasslands of Orinoco river basin).
- In the southern hemisphere, this climate is spread through South America (Campos grasslands of the Brazilian Highlands), and Australia (in Northern Australia - south of its monsoon strip).
- Monthly temperatures in this region can range between 20 to 32 degrees centigrade for lowlands, but the range increases as one moves away from the equator.
- Annual average temperature is around 18 degrees centigrade
- The highest temperature occurs just before the onset of the rainy season i.e., April in the northern hemisphere, and October in the southern hemisphere. June, when the summer solstice occurs in the northern hemisphere, does not witness the highest temperature.
- During the rainy season, overcast in the sky leads to drop in the temperatures.
- During the hot season, noon temperatures often cross 37 degrees centigrade.
- Clear skies lead to rapid radiation loss in the night and even in the hot season, the temperatures drop to below 10 degrees centigrade. Night frost is a common occurrence during this season
- Thus, a typical characteristic feature of Savanna climate is the extreme diurnal range of temperature.
- The region is characterized by a hot, rainy season and cool, dry season.
- In the northern hemisphere, the hot and wet season starts in May and continues until September (e.g., Kano, in Nigeria). The rest of the year is dry and cool. Kano, which is located at an altitude of over 1500m above mean sea level, experiences over 80 cm of rainfall which happens mostly in the summer.
- In the southern hemisphere, the rainy season begins in October and ends in March.
- The length of the rainy season, as well as the total annual rainfall, decrease considerably as one moves away from the equator towards the desert fringes.
- Trade-winds are the prevailing winds of the region which bring rainfall in the coastal areas. They are easterly winds - flow from east to west, hence the rainfall is maximum on the east coasts
- They are the strongest in summer when the ITCZ is positioned over the hot desert. They exhaust all the moisture while travelling over the coastal areas and by the time they reach the continental interiors, they are relatively dry.
- In West Africa, the easterly trade winds blow off-shore bringing dust-laden, dry winds from the Sahara and reach the coast of Guinea. The local name for this hot, dry, dusty wind is Harmattan (meaning 'the doctor').
- Harmattan has a disastrous effect on the crops, but it also results in a cooling effect. It provides some relief from the damp air of Guinea by increasing the rate of evaporation.
- Trade-winds are the reason for distinct, alternate dry and wet seasons in the region. In summer, onshore trade winds bring moisture-laden winds causing rainfall. In winter, the winds are off-shore and keep the weather dry.
- The typical vegetation of this region is tall grass with short trees. The grassland is also described as 'bush-veld' or 'parkland'.
- Tree cover is the highest towards the equator, along with the river banks and decreases in density and height away from the equator.
- The trees are of the deciduous variety i.e., they shed their leaves during the dry and cool season in order to prevent transpiration losses. Acacia is a typical example of this variety.
- Other types of trees include those with broad trunks which act as water-storage spaces that help them survive the dry season or drought. E.g., baobabs, bottle trees etc.
- They are hardwood trees, sometimes thorny, which exude gum like the 'gum arabic'.
- The grass found in this region is very tall and coarse, reaching heights of up to 6-12 feet. Elephant grass, which is the tallest variety of grass, can even reach heights of 15 feet.
- The grass is compact, with long roots that reach down in search of water. During the dry season, the grass appears dormant and springs up during the rainy season.
- As one moves towards the desert, the grasslands eventually merge into thorny scrubs.
- Savanna is home to some of the largest terrestrial animals on this planet.
- The two main groups of animals include - herbivores and carnivores.
- Famous herbivores of savanna are zebra, giraffe, elephant, antelope etc. The herbivores are either endowed with great speed to run away or have camouflage skills to escape the carnivores
- Important carnivores of this region include lion, hyena, leopard, panther, puma, jaguar etc. They have powerful jaws and teeth for attacking other animals.
- Along the rivers and marshy lands, one can find reptiles like crocodiles, monitors, giant lizards apart from rhinos and hippos.
- The region has nomadic pastoralists such as the Masai, who are found in Kenya and Tanzania of Africa. They are dependent on their animal stock for their survival and lead a primitive lifestyle.
- Settled agriculture is also practised by many tribes such as the Hausa, who have also domesticated animals for their use in crop cultivation
- Plantation agriculture which is developed in northern Australia, eastern Brazil, and in central Africa is indicative of the immense agricultural potential of this region. Crops such as cotton, sugarcane, oil palm, groundnuts, coffee, and tropical fruits are cultivated.
- Small amounts of millets, bananas, and vegetables are also cultivated by the tribes for self-consumption.
- However, frequent droughts pose a risk to crop cultivation in the region, particularly in the long dry season.
- In many areas, intense rainfall during the rainy season led to leaching of topsoil and the nutrients like nitrates, phosphates, and potash. Hence, the soils have turned lateritic in many places, incapable of supporting crop cultivation
- The grass here is of poor quality and does not favour large-scale animal ranches which are found in the temperate grasslands. Hence, meat and dairy production are poor from this region.
- However, some regions have leveraged modern science and technology and have become leading exporters of meat and dairy products. For instance, Queensland of Australia.