The Savanna biome is part of a larger grassland biome and is mainly made up of flat grassland vegetation. Except for Antarctica, the grassland biome is present in all continents and spans over 20% of the Earth’s surface.
From this biome comes the Savanna biome, also called tropical grassland and temperate grassland.
Despite these different features, the two biomes have a common thing: grass that sustains the ecosystem, thus the name ‘grassland.’ The Savanna biome is characterized by dominant ground cover by grass species and scattered trees and shrubs.
What is the Savanna Biome?
A savanna or savannah is a mixed woodland-grassland (i.e., grassy woodland) biome and ecosystem characterized by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses.
Four savanna forms exist: savanna woodland, where trees and shrubs form a light canopy; tree savanna, with scattered trees and shrubs; shrub savanna, with distributed shrubs; and grass savanna, where trees and shrubs are mostly nonexistent.
Savannas maintain an open canopy despite a high tree density. It is often believed that savannas feature widely spaced, scattered trees. However, in many savannas, tree densities are higher, and trees are more regularly spaced than in forests.
The South American savanna types cerrado sensu stricto and cerrado dense typically have densities of trees similar to or higher than that found in South American tropical forests, with savanna ranging from 800 to 3300 trees per hectare (trees/ha) and adjacent forests with 800–2000 trees/ha.
Similarly, the Guinean savanna has 129 trees/ha, compared to 103 for riparian forest, while Eastern Australian sclerophyll forests have average tree densities of approximately 100 per hectare, comparable to savannas in the same region.
Savannas are also characterized by seasonal water availability, with the majority of rainfall confined to one season. They are associated with several types of biomes, and are frequently in a transitional zone between forest and desert or grassland, though mostly a transition between desert and forest. Savanna covers approximately 20% of the Earth’s land area.
Unlike the prairies in North America and steppes in Eurasia, which feature cold winters, savannas are mostly located in areas with warm to hot climates, such as in Africa, Australia, South America, and India.
Key Takeaways: Savanna Biome
- Animals, including elephants, giraffes, lions, and cheetahs, make their homes in the savanna.
- Due to its open environment, camouflage and mimicry are essential for animal survival in the savanna.
- Savannas have extreme wet seasons and dry seasons. They can receive over four feet of rain during the wet season, and as little as a few inches during the dry.
- Due to this lack of precipitation, it can be very difficult for large plants like trees to grow in savannas.
- While savannas are located on six of the seven continents, the largest are found in equatorial Africa.
Savanna Biome Locations
The Savanna biome is a tropical grassland. It is located between the two tropics, the Tropic of Cancer to the north and the Tropic of Capricorn to the south. The area between the tropics is what is known as the tropical grasslands.
The biome covers over half of Africa, most of South America, and portions of Asia, such as India. For instance, in Africa, the biome is mostly in the Eastern part, including Kenya and Tanzania.
Acacia savannas are mostly spread in the region. These biomes have provided habitat for various wild animals, leading to the establishment of animal game parks and reserves. Notable ones are the Maasai Mara in Kenya and the Serengeti in Tanzania. These two are home to one of the most unique animal migrations in the world.
Savanna Biome Climate
The climate of this biome varies with the pre-existing season. There are two distinct seasons, consisting of a wet and a dry season.
The wet season comes during summer, while the dry season comes during winter. The climate during the dry season is disastrous to animal and plant life since most plants wither and dry up, leading to no food for the animals.
Most of the rain in the Savanna biome is from the wet season. With the warmth of the Savanna, there is more rainfall. Also, there is the sprouting of healthy plants due to adequate water. Rivers flow, and ponds of water fill with water.
The two seasons of the biome are the key to determining precipitation in the ecosystem. There are two major rainy seasons per annum.
The dry season experiences lower rainfall of about 4 inches per annum for a period of 4 months, spanning from October to January. On the other hand, the wet season, with an average of 25 inches, provides a lot of rainfall for the biome.
This results in the presence of constant precipitation regardless of the intensity and, consequently, adequate water for plant life and animal life all year long.
Despite the presence of two dominant seasons, there are other predisposing factors preventing equal rainfall all over the Tropical grasslands.
A case in point is the distance from the Equator. Areas around the Equator, characterized by equal days and nights, receive more rainfall due to the high amount of solar heating relative to other areas far from the equator.
The climate of the Savanna is gradually changing for the worse. Human interference with the original grasslands has led to a lot of destruction of the ecosystem and the reduction of forest cover due to deforestation. In some areas, it has led to desertification, thus changing the climate of the place.
Overgrazing and artificial fires have also contributed to a lot of harm to the Savanna biome. Nonetheless, these fires do not always damage the soil or plant life. For sure, they destroy habitats and scorch both animal and plant life, but they also help regenerate grass every year. Also, they regulate plant life and animal populations to ensure balance in the ecosystem.
Savanna Biome Temperature
The Savanna biome has an average temperature of 25 °C. It goes as high as 30 °C during the summer and as low as 20 °C in winter. Because of the slight temperature changes within the range of just between 20 °C and 30 °C in the Savanna biome, it is easy for the animals and plants to adapt.
Though there are only two seasons in the biome, the dry season can be further divided into two due to the range in temperatures.
The first one is the cold, dry season. It is characterized by high mid-day temperatures of about 29 °C but experiences lower temperatures of about 21 °C at night.
The second dry season is the warm, dry season, which experiences day temperatures of 32 °C to 38 °C. This is caused by the nature of the rays of the sun, which are close to vertical, thus the high temperatures.
Savanna Biome Soil
The soil in the savannah is not very fertile and only has a thin layer of humus made up of decomposed plant and animal matter. It is porous, which means the water drains away very quickly. Soils tend to be red due to high iron content.
The hummus gives the plants nutrients. The nutrients in the soil are found near the surface as they come from decayed organic matter (vegetation) from the previous growing season. This organic matter decays rapidly due to the high temperatures.
There are four layers of soil in the savanna grassland:
- Humus
- Hardpan of laterite
- Red clays and re-deposited silica
- Bedrock
Plant roots cannot penetrate the hardpan layer, which restricts vegetation growth.
There are generally 6 types of soil in the savannahs around the world.
- Lithosols – These are not very fertile and consist mostly of stones and gravel.
- Lateritic – these soils have an iron content, which makes the soil look reddish. It is also not very fertile.
- Cracking clays – This soil can hold much water, but dries out and cracks easily. It isn’t easy to cultivate because heavy machinery is needed to dig the soil.
- Red yellow earths – Red earth is dry, and yellow earth is not very fertile.
- Saline and alluvial – This is the soil found near waterways and estuaries. It is the most fertile of the soil types in the savannah.
- Deep sands – This is very sandy soil and hardly fertile at all. They are nearer to the desert biome.
Savanna Biome Plants
Plantlife in the Savanna is vastly adapted to cope with the climate. There are a variety of plant species in this biome, both tree and grass species.
Trees and grasses grow in the biome. These grasses grow to heights of as low as 80cm to as high as 350cm. There are also serious environmental weeds amongst the woody plant species.
Plants
- Acacia
- Baobab
- Pine
- Palm
Weeds
- Prickly Acacia (Acacia nilotica)
- Rubbervine (Cryptostegia grandiflora)
- Mesquite (Prosopis spp.)
- Lantana (Lantana camara and L. montevidensis)
- Prickly Pear (Opuntia spp.)
Grass
- Rhodes grass
- Red oat grass
- Lemongrass
- Star
- Buffel grass (Cenchrusciliaris)
- Giant rat’s tail grass (Sporoboluspyramidalis)
- Parthenium (Partheniumhysterophorus)
- Stylos (Stylosanthes spp.)
- other legumes
Others
- White sage
- Spotted cactus
- Cottonseed
- Rosemary
In as much as the Savanna biome is grassland, there are areas in the biome with open patches devoid of grass.
The grasses take on a brown, desert-like color during the dry season, probably due to low photosynthesis. All the same, when the seasons change, and it is humid again, they turn green.
Plus, there are a few vast spaces that favor the scattered growth of shrubs.
The trees grow to an average height of 6m. Plants in this biome have developed long taproots constituting a hydrophilic root system that can extend deeper into the soil in search of water.
These trees have large trunks to store excess water when there is adequate water in the biome to prepare for the dry seasons. Their bark is hardened and thick, and they are prone to wildfires in the forests. Wildfires easily spread in the Savanna biome due to the vast presence of grass.
The leaves of the plants are deciduous and fall during the winter season. Since leafy plants are at risk of losing a lot of water to the atmosphere through transpiration, they shed their leaves once a season to conserve water.
Savanna Biome Animals
The Savanna biome is one of the most diverse biomes in terms of animals. It’s not only aided by the vastness of the tropical grassland but also by the varying changes in the climate. This biome supports one of the world’s most renowned species of animals.
Herbivores
- Zebras
- Gazelles
- Warthogs
- Elephants
- Kangaroo
- Rhinoceroses
- Hippos
- Buffalo
- Baboons
- Antelopes
Carnivores
- Lions
- Cheetahs
- Hyenas
- Leopards
- Crocodiles
- Snakes
- Meerkats
- Jackals
- Bat-eared foxes
Birds
- Parrots
- Parakeets
- Kingfishers
- Finches
- Ostriches
Insects
- Ants
- Termites
Most of these animals are found in the African Savanna. The South American Savanna has fewer mammals but has more bird species. Also, it is only in the Australian Savanna that hosts mammals such as the kangaroos. Overall, the Savanna biome is home to thousands of insect species that attract birds for feeding and nesting.
The carnivore population grows exponentially during the rainy season. The reason being, the rainy season leads to more grass growth in the savanna, leading to more reproduction of the herbivores.
As keystone species, carnivores such as lions and cheetahs have to be present in the ecosystem in order to strike a balance in the biome. They prevent incidences of overgrazing that can arise due to the overpopulation of prey species like the gazelles and zebras.
In spite of a large number of animals in the biome, there is always enough food for all, especially for the herbivores. Each of these animals has developed uniquely different feeding habits that reduce competition for food.
For instance, giraffes feed on the top vegetation on trees that other animals, such as the zebra, cannot reach. Elephants feed on leaves from shorter trees.
Zebras feed on shrubs and tall grasses, while wildebeests and gazelles feed on medium and short grasses, respectively. It is for this reason that these groups of animal species can be found in the same area, feeding without competing for food.
The dry season leads to loss of water through evaporation and transpiration. Consequently, there is inadequate drinking water for animals, and the soils are dry and cracked due to extensive loss of water. With no means of plant growth, herbivores start to decline in number. Carnivores may increase slightly due to abundant food.
Due to the fluctuation in climatic levels, animals migrate in search of food. They may migrate to very far places to search for water and pasture. The migration varies among animals.
There are some that migrate only to come later when the rainy season is back, while others migrate and never return. Again, some move during the rainy season.
Fires
Due to the number and types of vegetation in savannas, fires can occur at different times of the year in both the dry and wet seasons. During the wet season, lightning strikes often cause natural fires in savannas.
In the dry season, dry grasses can be fuel for the fires. With the advent of human settlements in some savanna areas, controlled burns may be used for land clearing and cultivation.
Human Impacts
Natural wildfires happen during the dry seasons in savannas. Humans can also be the cause of fires. Many savanna plants actually thrive after fires. Humans living in savannas sometimes stop natural fires when they come near their cities and homes. Both of these things can damage the ecosystem.
Savannas are often used for farming. This usually requires trees to be removed to make room for crops. This affects the habitats of animals and plants that depend on these trees to survive.
Domesticated animals, or livestock, can cause a shortage of food for wildlife by overgrazing on the plants around them. This leaves the soil exposed and at risk of erosion, which is when soil is moved away by wind or rain. This makes it harder for new plants to grow back. This process is called desertification.
Poaching is a major threat for wildlife, especially in Africa. Poaching means hunting for animals illegally. Large grazing mammals (e.g., elephants and rhinoceros) are poached for their tusks and horns. These parts are sold around the world for very high prices. The loss of animals due to poaching can alter the entire ecosystem.
FAQs.
- What do savannas look like? Savannas look like rolling grasslands dotted with isolated shrubs, trees, and sporadic patches of forest.
- What is a tropical grassland? Savannas differ from traditional grasslands because they support scattered tree growth (hence the word “tropical”), creating a mix of open grassland and tree cover. This tree growth is not dense enough to form a closed canopy, thus allowing enough sunlight to reach the ground and support ample grass growth.
- What’s the difference between a savanna and a desert? Deserts get too little precipitation to support trees, grass, or any plants. Savannas have just enough rainfall or access to water to support grass—lots of grass—and sporadic trees.
- Where are savannas located in the world? Savannas flank tropical rainforests to the north and south. The most famous stretches of savanna are in Africa, but they also occur in Australia, India, Southeast Asia (Myanmar and Thailand), and South America.