Savanna Biome
The savanna is the biome of the great migration, the lion pride at sunset, and the giraffe reaching into an acacia tree — Africa's most iconic landscapes, shared in different forms by tropical Australia, central Brazil and parts of India. A tropical grassland scattered with trees, the savanna is shaped by a relentless seasonal rhythm: months of flooding rains followed by months of bone-dry heat, punctuated by sweeping grass fires that are as much part of the ecology as the rains themselves.
- Area Coveredapprox. 20 million km²About 15% of Earth's land surface
- LocationTropicsSub-Saharan Africa, northern Australia, central Brazil, India
- Annual Rainfall500–1,300 mmConcentrated in a wet season of 6–8 months
- Temperature20°C to 35°CWarm year-round; the coolest month rarely below 18°C
- Dry Season4–8 monthsNear-zero rainfall; grasses dry out and fire risk peaks
- Large MammalsMost diverseMore large herbivore species than any other biome
How does the savanna compare to neighbouring biomes by rainfall?
The savanna sits between dry grassland and tropical forest — its rainfall is seasonal rather than year-round.
What distinguishes the savanna is not the total rainfall but its extreme seasonality. During the wet season, water is abundant and grass grows rapidly. During the dry season, virtually no rain falls for months, the grasses turn brown, fires sweep across the landscape, and animals must migrate or live off stored fat and whatever water they can find.
What is the Savanna Biome?
A savanna is a tropical or subtropical biome characterised by a continuous grass layer with scattered trees that are tall enough to let light reach the ground between them. This distinguishes it from forest (where the tree canopy closes overhead) and from open grassland (where trees are absent or very rare). The mixture of grass and trees creates a mosaic of open and shaded habitats that supports extraordinary biodiversity — more species of large grazing mammals than any other biome on Earth.
The word savanna entered English from the Taíno word zabana, used by indigenous people of the Caribbean to describe flat, treeless plains. Today it is used more broadly for the tree-dotted tropical grasslands of Africa, South America and Australia. Africa has by far the most extensive savannas — they cover approx. 65% of the entire continent, from the Sahel south to the Kalahari. Brazil's Cerrado is the world's most biodiverse tropical savanna and a major global carbon store. Northern Australia's savanna woodlands stretch across 25% of the continent.
Where is the Savanna found?
Savannas are found in a broad band around the equator, typically between 5° and 20° north and south of it, where seasonal rainfall alternates with a long dry season. Africa's savannas run in a great arc south of the Sahara — from Senegal and Guinea in the west, through Mali, Nigeria, Ethiopia and Kenya, to Tanzania, Zambia, Zimbabwe and South Africa. This African savanna zone, called the Sudanian, Guinean and East African savannas depending on region, is the most wildlife-rich grassland system in the world. Brazil's Cerrado covers approx. 2 million square kilometres of central Brazil — an area roughly the size of Western Europe — and is the world's most biodiverse savanna, with over 10,000 plant species. Northern Australian savannas, dominated by eucalyptus and Acacia trees over a grass understorey, cover Queensland, the Northern Territory and Western Australia. Smaller savanna areas occur in India (particularly in the Deccan plateau) and in parts of Southeast Asia.
Climate and seasons
The savanna climate is defined by two seasons rather than four: a wet season when rain is abundant and everything grows rapidly, and a dry season when almost no rain falls and the landscape bakes. Temperatures are warm year-round — typically 20–30°C — and even the coolest month rarely drops below 15°C. The wet season, lasting roughly 6–8 months in most savannas, brings torrential rains that can flood low-lying areas and cause rivers to overflow. The dry season brings fire. As the grass dries out and the landscape becomes tinder-dry, lightning strikes, natural combustion or human activity ignites fires that sweep for kilometres, burning off the standing grass. Most savanna trees and grasses are completely adapted to this annual burning — many require it to complete their life cycles.
The transition between wet and dry seasons drives one of the most dramatic ecological phenomena on Earth: the mass migrations of large herbivores following the rains and new grass growth across vast distances. In East Africa this creates the famous wildebeest migration. Across West Africa, millions of birds migrate south to savanna wetlands as dry-season rainfall disappears from the Sahel.
Plants of the Savanna
Savanna vegetation is a mixture of grass layer and scattered trees, each adapted to the same fire and drought cycle but in different ways. The dominant trees of African savannas are acacias — their flat-topped canopies, thorny branches and small leaves are one of the most recognisable silhouettes in nature. Baobab trees, with their swollen, water-storing trunks, can live for over 1,000 years and serve as hotels, water sources and food trees for hundreds of species. In the Australian savanna, eucalyptus dominates — fire-resistant, fast-growing trees with oil-rich leaves that actually encourage fire. Brazil's Cerrado has evolved a uniquely diverse tree flora with gnarled, cork-barked trees whose thick bark protects them from the frequent fires.
The grass layer — dominated in Africa by red oat grass, star grass, elephant grass and many others — is fire-adapted to its core. After a grass fire, the buried growing points (meristems) activate within days, pushing up vivid green new growth that attracts grazing animals from great distances. This post-fire "green flush" is one of the key mechanisms driving animal migrations across the savanna.
Animals of the Savanna
The African savanna supports the greatest diversity of large mammals on Earth — a legacy of the millions of years during which Africa's wildlife evolved alongside both humans and other predators, unlike the megafauna of North America and Australia that was wiped out as humans arrived. Elephants, the largest land animals, engineer the landscape by pushing over trees, digging waterholes and creating paths that other species use. Giraffes browse the upper canopy of acacias that no other herbivore can reach. Zebras, wildebeest, buffalo, impala, gazelles and many more species of antelope graze the grass layer, their different preferences for grass height and species allowing many species to coexist. Lions, the savanna's apex predators, hunt in coordinated family groups. Cheetahs sprint at up to 120 km/h to catch gazelles. Leopards drag kills into trees to keep them from lions and hyenas. Wild dogs hunt in relay, pursuing prey until it exhausts. Spotted hyenas are more often hunters than scavengers, despite their reputation. Vultures, storks and marabous circle overhead, waiting for their turn at the carcass.
Savanna food web
The African savanna supports the world's most complex and diverse large-mammal food web. The base is an extraordinarily productive grass and shrub layer: during the wet season, savanna grasses grow rapidly to provide a continuous carpet of food. The herbivore layer is divided into guilds that avoid competition: elephants eat bark, branches and tough vegetation that smaller animals cannot process; giraffes browse the upper acacia canopy (2–6 metres) that other browsers cannot reach; zebra eat the tough upper stems of long grass; wildebeest take the leaf layer; Thomson's gazelles graze the short, nutritious grass the wildebeest leave behind — each species exploiting a slightly different food resource. This "grazing succession" is one of ecology's most elegant examples of resource partitioning. Carnivores are similarly specialised: lions hunt cooperatively, taking large prey such as buffalo and wildebeest; cheetahs sprint to catch gazelles; leopards ambush prey and carry kills into trees; wild dogs exhaust prey over long distances; hyenas and jackals are both hunters and scavengers. Vultures — five species in the Serengeti — form a hierarchical scavenging guild at carcasses, each species feeding on a different part. Dung beetles rapidly bury animal droppings, cycling nutrients back into the soil within hours of deposition.
How animals adapt to the Savanna
Savanna animals have evolved remarkable adaptations to heat, drought, and the boom-bust cycle of wet and dry seasons. The giraffe's extraordinary neck — up to 2.4 metres long — gives access to food sources no other browser can reach, but also creates physiological challenges: the giraffe has an unusually powerful heart (weighing up to 11 kg) to pump blood 2 metres up to the brain, and a complex system of valves to prevent blood rushing to the head when it bends to drink. Elephants use their ears — richly supplied with blood vessels close to the surface — as giant cooling fans, flapping them to dissipate body heat. Their trunk serves as a snorkel when swimming and a precision tool for selecting individual fruit or leaves. Many savanna animals are pale or tawny-coloured, reflecting solar radiation and providing camouflage in the dry-season grass. Zebra stripes may confuse the tsetse fly's visual system, reducing biting fly attacks. Acacia trees have evolved their own defences against the savanna's many herbivores: thorns against large mammals; toxic tannins that diffuse through the leaves within minutes of browsing (signalling neighbouring trees via airborne chemicals to do the same); and symbiotic relationships with ants (in some species) that swarm out to sting browsers that touch the tree. During the dry season, many smaller animals aestivate (enter a dormant state) in underground burrows, reducing their water and energy needs until the rains return.
Threats and conservation
Savannas face threats from multiple directions simultaneously. Agricultural conversion — for maize, soya, cotton and cattle ranching — has destroyed large areas of both African and South American savanna. Brazil's Cerrado has lost approximately 50% of its original cover to agriculture, predominantly soya farming for animal feed export. Bushmeat hunting has depleted wildlife populations across large areas of African savanna. Elephant poaching for ivory nearly drove African elephants to extinction in the 1980s. In East Africa, pastoralism by expanding human communities is reducing the land available for wildlife. Climate change is shifting rainfall patterns, extending dry seasons and increasing the severity and frequency of droughts in savanna regions. The fragmentation of savanna into smaller and smaller patches is reducing gene flow between wildlife populations and making animals increasingly vulnerable to disease and climate stress.
Deeper dive: fire ecology and the savanna carbon debate
The relationship between savanna, fire and carbon is one of ecology's most complex and debated topics. Savannas burn regularly — most African savannas burn every 1–4 years — releasing carbon from the grass and trees into the atmosphere. But the grass grows back rapidly, recapturing the carbon within a year or two. This means savannas are roughly carbon-neutral over short timescales, unlike deforestation (where the carbon is not recaptured). However, savannas can become significant carbon sinks if tree cover increases — a process called "bush encroachment" that is occurring in parts of Africa as CO₂ levels rise (because higher CO₂ helps trees compete with grass) and fire suppression allows trees to establish.
Brazil's Cerrado is a particularly important case. Despite its remarkable biodiversity, the Cerrado has received far less legal protection than the Amazon rainforest — and has lost roughly twice as much area to agricultural conversion. Scientists estimate the Cerrado stores approx. 13.7 billion tonnes of carbon in its soils and trees, and its conversion is releasing that carbon at a rate that makes it one of Brazil's largest sources of greenhouse gas emissions. Protecting the Cerrado is increasingly recognised as essential to global climate targets.
The savanna is where the drama of predator and prey plays out on the grandest possible stage. The Grassland Biome explores the temperate equivalent of this open landscape — cooler, less wildlife-rich, but equally vital to human civilisation.