Savanna

A savanna or savannah is a special kind of land where trees and grasses grow together. The trees in a savanna are spaced far apart, so their leaves do not form a thick roof over the ground. This lets sunlight reach the grasses and other plants below. Savannas can look different depending on where they are. Some have many trees with thin leaves, while others have only a few scattered trees or just shrubs.

Even though savannas seem to have few trees, they often have many more trees than people think. In some places, like South America, savannas can have as many trees as forests nearby. The trees might just be spread out more evenly.

Savannas usually have wet and dry seasons. Most of the rain falls in just a few months, and the rest of the year can be dry. These lands are found in many warm places around the world, such as Africa, Australia, South America, and India. They cover about 20% of the Earth's land, acting like a bridge between deserts and forests.

Etymology

The word "savanna" comes from the Spanish word sabana. The Taíno people used this word to mean "treeless grassland" in the West Indies.

Long ago, the word came into English as Zauana. It described lands ruled by Spanish kings. Over time, the spelling changed to "savannah." Explorer William Dampier used this spelling when he wrote about woodlands in the Bay of Campeche, Sumatra, and the Philippines.

Distribution

Many grassy areas with trees, shrubs, and grasses are called savannas. It can be tricky to know which places are true savannas because of how we group climates. This is especially true near the Congo and Amazon Rivers.

In North America, the word "savanna" describes open landscapes such as barrens, prairie, glade, grasslands, and oak opening. Savannas have trees that space out, letting grass grow below.

Rainfall and the dry season with wildfires help shape savannas. In places like Belize, Central America, Mexico, and South America, savanna plants look alike. Whether an area is a forest, savanna, or grassland depends on climate and events like fires.

Savannas are often found in flat areas and on lone hills. Rivers in these spots change their paths more than they dig deeper, and flooding can change the land.

Ecology

Savannas are special places where trees and grasses grow together. In tropical America, you can find trees like Curatella, Byrsonima, and Bowdichia, along with grasses such as Leersia and Paspalum. In East Africa, trees like acacias, baobabs, and Euphorbia grow among grasses.

Animals in African savannas include giraffes, elephants, buffaloes, zebras, and antelopes. In Australian savannas, you’ll often see kangaroos and wallabies, along with animals like cattle and horses that humans have brought there.

Threats

Savannas are places where grasses and trees grow together. But they face many challenges that could change how they look and work.

One big issue is how people use fire to manage the land. In the past, groups like Native Americans and people in Australia and New Guinea used fires to shape the land. These fires helped keep the trees apart so grasses could grow. Today, changes in how fires are used can let forests grow where savannas used to be.

Animals that graze, like sheep and cattle, also change savannas. When these animals eat the grass, it can help trees grow because there is less competition for water. But too many grazing animals can hurt the soil and let unwanted plants grow.

In places like Australia and South America, people cut down trees to give animals more food. This can make the land better for grazing but also changes the natural balance of plants and animals.

Finally, new plants that are not native to savannas can cause problems. These plants can grow faster than local plants and take over areas where native plants used to grow. Climate change may also affect savannas.

Savanna ecoregions

Savannas are special places where grass and trees grow together. In some savannas, there are very few trees and lots of grass. In others, there are more trees close together. There are different kinds of savannas around the world.

Some savannas are found in warm places, like Kenya and Brazil. Others are in cooler areas, like New South Wales. Some have trees that lose their leaves in winter, like in Portugal. There are also savannas that flood during certain times of the year, like the Nile Delta flooded savanna. And some savannas are high up in the mountains, like in the Colombian Andes.