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.

Savanna

95 entries

Common Group

Taxonomy

Conservation Status

Ecosystem

Everyday Group

Diet

Population Trend

System (Realm)

Threats

Relationship to People

Living or Extinct

Where It Lives

African Baobab

African Grey Parrot

African Lion

Aloe maculata

Alstonia scholaris

American Cockroach

American Robin

Archer's buzzard

Ardipithecus kadabba

Argentine Black and White Tegu

Arion ater

Arthrocereus rondonianus

Black Mamba

Blue Morpho

Blue Poison Dart Frog

Blue Wildebeest

Boomslang

Bracken

Brazilian three-banded armadillo

Brown Anole

California Tiger Salamander

Century Plant

Cheetah

Chimpanzee

Chionanthus virginicus

Chlamydosaurus Kingii

Coastal Taipan

Cockchafer

Common Cuckoo

Common quail

Common Warthog

Coral Snake

Corn Snake

Daddy Long-Legs Spider

Dalbergia melanoxylon

Danaus Plexippus

Dark fruit-eating bat

Eastern Blue-tongued Skink

Eastern Diamondback Rattlesnake

Eastern Redcedar

Emperor Scorpion

European Adder

European Pine Marten

Feral Cat

Frilled-neck Lizard

Frilled-necked Lizard

Gaboon Viper

Giraffe

Goldeneye cichlid

Greater Kudu

Grey partridge

Grey plover

Hemaris thysbe

House Mouse

Hyacinth Macaw

Impala

Indian Pangolin

King Cobra

Kori Bustard

Little free-tailed bat

Longleaf Pine

Mabee's Salamander

Mediterranean Fruit Fly

Naja Naja

Nilgai

Northern giraffe

Olive Baboon

Panamanian spiny pocket mouse

Pancake Tortoise

Peacock Butterfly

Pineapple

Pteridium Aquilinum

Red Admiral

Reticulated Flatwoods Salamander

Robber Fly

Rubber Eel

Ruby-throated Hummingbird

Sable Antelope

Savannah Monitor

Sloth Bear