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 enough apart that their leaves do not form a thick roof over the ground. This allows sunlight to reach the grasses and other plants below. Savannas can look different depending on the place. 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, which was borrowed from the Taíno language. In Taíno, it means "treeless grassland" in the West Indies.

Long ago, the word entered English as Zauana. It was used to describe the lands of the kings of Spain. Over time, the spelling changed to "savannah," especially in British English. Explorer William Dampier used this spelling when he wrote about woodlands he saw in places like the Bay of Campeche and later in Sumatra and the Philippines.

Distribution

Many grassy areas with trees, shrubs, and grasses were called savannas long ago. The way we classify climates can make it hard to know which areas are truly savannas. This is especially true for large areas near the Congo and Amazon Rivers.

In North America, the word "savanna" is used for many open landscapes like barrens, prairie, glade, grasslands, and oak opening. Savannas have trees that do not grow too close together, allowing grass to grow underneath.

Rainfall and dry season wildfires are important for savannas. In places like Belize, Central America, Mexico, and South America, savanna plants look similar. Whether an area is a forest, savanna, or grassland depends not just on climate but also on past events like fires.

Savannas often appear in flat areas and on isolated hills. Rivers in these areas change their paths more than they dig deeper, and flooding can shape 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 special places where grasses and trees grow together. But these areas are facing 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, change how fires happen, and take over areas where native plants used to grow. Climate change may also affect savannas, possibly letting forests grow where grasses once thrived.

Savanna ecoregions

Savannas are special places where grass and trees grow together. In some savannas, there are very few trees and lots of grass, while 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.