Biome

Savanna

Grassland, Savanna and Shrubland Biomes

Savanna

A biome of tropical and subtropical grassland dotted with scattered trees and shrubs, found within about thirty degrees of the equator between the tropical rainforest and the desert. Savanna carries a long dry season and a shorter wet season, with mean monthly temperatures above 18C year round and highly seasonal rainfall that sustains grass but not a closed forest canopy.

Facts

Climate

Annual Precipitation (mm)

1200 1

WorldAtlas gives a global savanna range of 800 to 1,600mm annually with under 60mm in the driest month; 1,200mm is the midpoint of that range, not a single measured site.

Typical Low Temperature (C)

18 1

Year-round mean monthly low per WorldAtlas; wet-season means run 25 to 30C and dry-season means 20 to 25C.

Typical High Temperature (C)

30 1

Learn More

Savanna: The Grassland That Rain Builds, Not Heat

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

The savanna is often mistaken for a simpler cousin of the desert, a place that is merely hot and dry. It is neither. What actually draws the boundary of a savanna is not temperature at all, since mean monthly temperatures sit above 18C year round with only a modest swing between wet and dry seasons, but rainfall, and specifically the shape of rainfall over a year. A savanna gets real rain, 800 to 1600mm a year by some measures, enough to grow grass tall enough to hide a lion. What it does not get is rain spread evenly through the year. Almost all of it falls in a single wet season, and for months at a stretch, sometimes with under 60mm falling in the driest month, almost none falls at all.

That seasonal whiplash is what keeps a savanna from becoming a forest. Trees can survive the dry season, but not enough of them can establish fast enough during the brief wet season to close a canopy before the rain shuts off again, so the biome settles into an equilibrium of scattered trees standing over a nearly continuous grass layer, rather than tipping all the way to forest or all the way to bare ground. Fire is part of what holds that balance in place. Grass that cures out in the long dry season burns readily, and fire on savanna, including the African savanna, is common enough to count as an ordinary feature of the biome, one that keeps woody growth from closing back over the grass rather than a rare event.

The biome forms a band on both sides of the equator, sitting between the closed canopy tropical rainforest nearer the equator and the true desert farther away, on every continent that reaches those latitudes: East Africa's open plains, Brazil's Cerrado, northern Australia's tropical savanna. Two ecosystems already on this atlas, the Serengeti and the Cerrado, were classified under the temperate Grassland biome before this entry existed; both are correctly savanna, and the record now reads that way.

Why the Serengeti Was Never Really Grassland

This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.

Two of this atlas's best known ecosystems, the Serengeti and Brazil's Cerrado, were filed under the Grassland biome from the founding wave onward, and by the ordinary meaning of the word, that was not unreasonable: both are open, sun struck expanses of grass stretching to the horizon. But ecology draws its categories from climate and structure, not appearance, and by that measure both places have always been something more specific than grassland. The Cerrado's own description already called it, without qualification, the most biodiverse savanna ecosystem on Earth, and carried the alias Brazilian Savanna. The Serengeti's own description already called it a savanna grassland ecosystem. The biome record simply had not caught up to what the entities themselves already said.

The distinction matters because temperate grassland and tropical savanna form under different climates. A savanna stays warm to hot year round and has a rainy season and a dry season, with most of its rain falling in just a few months; that long dry season is what keeps the grassland from closing over into forest. A temperate grassland, the prairie of the American Midwest or the steppe of Central Asia, is instead defined by real seasonal swings in both temperature and precipitation across the year, a different climate pattern that produces a superficially similar grass dominated landscape by a different route.

The Serengeti's own wildfire, nitrogen cycle and decomposition facts, and the Cerrado's own wildfire demonstration, already described exactly this savanna dynamic before either was reclassified: seasonal drought curing the grass into fuel, fire recycling nutrients and holding back tree cover, a new flush of growth on the next rain. Reclassifying both ecosystems under the newly minted Savanna biome does not change a single fact already on either page. It corrects the shelf they sit on to match what was already written on the label.

Connections

Demonstrates

Drought

Source National Oceanic and Atmospheric Administration

Wildfire

Source Encyclopaedia Britannica

Home To

African Baobab

Source Adansonia digitata (Wikipedia)

African Grey Parrot

Source Animal Diversity Web, University of Michigan Museum of Zoology: Psittacus erithacus (Animal Diversity Web)

African Lion

The zoo places wild lions from the southern fringe of the Sahara to northern South Africa, the range of the Savanna biome.

Source Lion (Smithsonian's National Zoo and Conservation Biology Institute)

Aloe maculata

Source Plants For A Future: Aloe maculata

Alstonia scholaris

Source Alstonia scholaris (Wikipedia)

American Cockroach

Source Animal Diversity Web, University of Michigan Museum of Zoology: Periplaneta americana (Animal Diversity Web)

American Robin

Source NatureServe Explorer: Turdus migratorius

Archer's buzzard

Source Archer's buzzard (Wikipedia)

Ardipithecus kadabba

Source Ardipithecus kadabba (Wikipedia)

Argentine Black and White Tegu

Source Wikipedia: Argentine Black and White Tegu

Arion ater

Source Animal Diversity Web, University of Michigan Museum of Zoology: Arion ater (Animal Diversity Web)

Arthrocereus rondonianus

Source Arthrocereus rondonianus (Wikipedia)

Black Mamba

Source Black Mamba (Wikipedia)

Blue Morpho

Source Wikipedia: Morpho menelaus

Blue Poison Dart Frog

Source Wikidata: Blue Poison Dart Frog

Blue Wildebeest

Source Blue Wildebeest (Wikipedia)

Boomslang

Source Wikipedia: Boomslang

Bracken

Source NatureServe Explorer: Pteridium aquilinum

Brazilian three-banded armadillo

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Tolypeutes tricinctus

Brown Anole

Source NatureServe Explorer: Anolis sagrei

California Tiger Salamander

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Ambystoma californiense

Century Plant

Source NatureServe Explorer: Agave americana

Cerrado

Source World Wildlife Fund

Cheetah

Source Cheetah (Wikipedia)

Chimpanzee

Source Chimpanzee (Wikipedia)

Chionanthus virginicus

Source Chionanthus virginicus (Wikipedia)

Chlamydosaurus Kingii

Source Wikipedia: Frilled lizard

Coastal Taipan

Source The Reptile Database: Coastal Taipan

Cockchafer

Source Animal Diversity Web, University of Michigan Museum of Zoology: Melolontha melolontha (Animal Diversity Web)

Common Cuckoo

Source Animal Diversity Web, University of Michigan Museum of Zoology: Cuculus canorus (Animal Diversity Web)

Common quail

Source Animal Diversity Web, University of Michigan Museum of Zoology: Coturnix coturnix (Animal Diversity Web)

Common Warthog

Source Common Warthog (Wikipedia)

Coral Snake

Source NatureServe Explorer: Micrurus fulvius

Corn Snake

Source NatureServe Explorer: Pantherophis guttatus

Daddy Long-Legs Spider

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Pholcus phalangioides

Dalbergia melanoxylon

Source Plants For A Future: Dalbergia melanoxylon

Danaus Plexippus

Source NatureServe Explorer: Danaus plexippus

Dark fruit-eating bat

Source Dark fruit-eating bat (Wikipedia)

Eastern Blue-tongued Skink

Source Wikipedia: Eastern Blue-tongued Skink

Eastern Diamondback Rattlesnake

Source NatureServe Explorer: Crotalus adamanteus

Eastern Redcedar

Source Wikipedia: Juniperus virginiana

Emperor Scorpion

Source Wikipedia: Emperor Scorpion

European Adder

Source Animal Diversity Web, University of Michigan Museum of Zoology: Vipera berus (Animal Diversity Web)

European Pine Marten

Source Animal Diversity Web, University of Michigan Museum of Zoology: Martes martes (Animal Diversity Web)

Feral Cat

Source Wikidata: Feral Cat

Frilled-neck Lizard

Source Wikipedia: Frilled lizard

Frilled-necked Lizard

Source Wikipedia: Frilled lizard

Gaboon Viper

Source Gaboon viper - Wikipedia

Giraffe

Source Wikipedia: Giraffe

Goldeneye cichlid

Source Goldeneye cichlid (Wikipedia)

Showing 1 to 50 of 99 in Home To, page 1 of 2.

Long-Form Articles

Savanna: The Grassland That Rain Builds, Not Heat

Why the Serengeti Was Never Really Grassland

Sources

1. What Are The Characteristics Of A Tropical Savanna Type Of Climate? (WorldAtlas)

WorldAtlas

Precipitation section
On average, this climatic zone receives between 800 and 1,600 millimeters of rain annually.
Introduction
During the wet season, temperatures are between 78 to 86 °F (25 - 30 °C).
Introduction
Throughout the year, mean monthly temperatures soar above 64 °F (18 °C).
WorldAtlas, tropical savanna climate characteristics, precipitation section
On average, this climatic zone receives between 800 and 1,600 millimeters of rain annually.

Demonstrates

Home To

Long-Form Articles

Take a Related Quiz