Savannah
Savanna, also known as savannah, is an ecosystem combining woodland and grassland. Read on to learn about the savanna, including information on savanna physical features and handy resources to support your teaching.
At least 20% of the land on Earth is considered savanna. Some savannas are tropical, sometimes referred to as ‘tropical grassland.’ Areas of savanna are typically located in a transitional zone between desert and forest.
Savannas are found in areas without enough rainfall to support a forest, typically in regions that experience wet and dry seasons. Savannas are considered a type of grassland and generally are open and flat. In the dry season, wildfires are common in savanna areas.
What are the Types of Savanna?
Several types of savanna vary depending on the location and climate. These are:
Tropical and subtropical savannas are made up of tropical grasslands and shrublands. The most notable example of this biome is the savannas of Africa. These areas are known for their varied and exotic animals and provide a habitat for diverse species. Other large tropical savannas can be found in South America and Australia.
Temperate savannas have wetter summers and drier winters than other Savanna types. An example of this type of Savanna is the Great Plains of the United States. This type of Savanna has many names depending on where they are located worldwide. For example, in the US, they are called prairies, while in Asia, they are called steppes.
Mediterranean savannas have mild, rainy winters and hot, dry summers. As the name suggests, this biome can be found across the Mediterranean, including Spain, Italy, and Greece, but also in California, South Africa, and Australia.
As the name suggests, Flooded savannas regularly experience seasonal or year-round flooding. These regions are smaller than other Savannas but are found worldwide and are home to unique ecosystems adapted to the wet environment.
Montane savannas are located at high altitudes, typically on the sides of mountains. The largest and most prominent montane savannas are in Asia, Africa, and South America. Animals that live in these areas have adapted to wet and cool conditions and harsh sunlight.
Savanna Physical Features
Many physical features set savannas apart from other biomes.
- Scattered Trees
The most prominent of the savanna’s physical features is its scattered trees. These trees are what distinguish the Savanna from other grasslands. The scattered trees in the Savanna grow above a layer of continuous tall grass between the forest canopy and the ground.
- Wet and Dry Seasons
Another key savanna’s physical feature is its two distinct seasons: wet and dry. Savannas are typically in regions around 8° to 20° from the Equator, which means that the conditions are always very hot regardless of the season. The savanna’s wet season dates vary depending on which hemisphere it is in. In the Southern Hemisphere, the wet season typically occurs from October to March; in the Northern Hemisphere, it appears from April to September. During this wet season, there is an average annual rainfall of 80 to 150 cm, although this tends to be lower in the more central continental locations. On the other hand, the savanna’s dry season is generally longer than the wet season; however, its length can vary from two to 11 months. The average monthly temperature during the dry season is about 10 to 20 °C and about 20 to 30 °C in the wet season.
- Large Herds of Animals
The savanna is rich in grasses and tree life, making it attractive to large herbivores. As a result, many species have adapted to eat different plants for many kinds of herbivorous animals to live in the savanna. For instance, some animals are designed to eat low grass, while others are built to eat the leaves high up in the trees.
With the large herds of herbivores comes a range of predators. Animals such as lions, hyenas, cheetahs, leopards, and wild dogs are some of the most common predators in savannas.
Over time, the herbivorous animals in the savanna have developed a range of clever techniques to avoid predators. For instance, gazelles and ostriches use their speed to outrun their predators. Alternatively, animals like the giraffe, for whom running is not viable, use their height to spot predators from far off. Moreover, elephants use their massive strength and size to fight off predators.
Similarly, the savanna predators have also developed techniques to catch their prey. For example, the cheetah, the fastest land animal in the world, uses its immense speed to catch its prey, getting up to 70mph in short bursts. Moreover, predators like lions and hyenas hunt in groups and focus on separating the weakest animals from the rest of the herd.
- Fires
Another of the savanna’s physical features is the many fires. While fires are typically viewed in a negative light, they play a key role in maintaining the savanna’s vegetation. During the dry season, fires are needed to clear out the old, dead grass to make way for new growth. Most of the plants in the savanna will survive the fires, as they have long, deep roots that allow them to grow back quickly. The trees are also able to survive due to their thick bark. The animals that live in the savanna can also escape the fires unharmed. Some animals run to escape the fire, while others burrow deep into the ground to find safety. Unfortunately, millions of insects tend to die in the fires, but the bright side is that it provides ample food for other birds and animals.
What Animals Live in the Savanna?
Because savannas are widespread across the world and differ in their climate and seasons, there are a huge number of animals that call the savanna their home. The most famous and recognizable type of savanna, the African savanna, also happens to be home to some of the most famous and recognizable types of animals, such as giraffes, lions, rhinos, zebras, and buffalo.
Worldwide, there are many more animals that are native to the savanna. Kangaroos, ostriches, crocodiles, snakes, meerkats, leopards, and cheetahs can all be found in various Savannas worldwide. Each has specific adaptations that make them well-suited for living in the kind of Savanna that they occupy.
Large animals are common in pretty much all savannas except the Australian savannas. Instead, the Australian savannas are inhabited by many species of the Macropodidae family, which includes the likes of kangaroos and wallabies. This is because, several thousand years ago, a wide variety of very large mammals and reptiles became extinct after human beings first arrived. Today, in their place, you will find a range of domesticated and wild animals that humans have introduced. These animals include cattle, horses, camels, donkeys, and the Asian water buffalo.
What Plants Are Found in the Savanna?
Plants in the savanna, much like plants in other biomes, rely on sunlight to supply them with the energy they need to perform photosynthesis. Sunlight is abundant in savannas, particularly tropical savannas, as they are close to the equator; plants can receive around 10 to 12 hours of daylight most days. Savannas are dominated by grasses, hence why another term for tropical savanna is ‘grassland.’
Some of the plants you will find in savannas are:
- Rhodes grass
- Red oats grass
- Tar grass
- Eucalyptus trees
- Acacias
What Threats are faced by the Savanna?
The main threat faced by the savannas of the world is humans, who regularly cut down trees in the savanna, which upsets the delicate ecological balance of these areas. In addition, farmers will deforest areas of the savanna and then use the grass to feed cattle, which can make the savanna turn barren.
Humans are not the only threat to the savanna, however. Just as grazing cattle can severely reduce the amount of grass in a savanna area, herds of wild animals grazing will also reduce the amount of grass. It is why predators in the savanna play an important role in the ecosystem, as they keep the number of grazing herbivores down.
The savanna is also threatened during outbreaks of wildfires. These fires often spread during the dry season and burn through dry grass and young trees. These fires sometimes occur naturally and play an important role in reducing the tree canopy in the savanna. However, wildfires started by Humans can do more damage. Herbivores reduce the chances of wildfires by grazing on plants before they can dry out.
