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

Gran Chaco

Source World Wildlife Fund

Greater Kudu

Source Greater Kudu (Wikipedia)

Grey partridge

Source Animal Diversity Web, University of Michigan Museum of Zoology: Perdix perdix (Animal Diversity Web)

Grey plover

Source NatureServe Explorer: Pluvialis squatarola

Hemaris thysbe

Source NatureServe Explorer: Hemaris thysbe

House Mouse

Source NatureServe Explorer: Mus musculus

Hyacinth Macaw

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Anodorhynchus hyacinthinus

Impala

Source Impala (Wikipedia)

Indian Pangolin

Source Animal Diversity Web, University of Michigan Museum of Zoology: Manis crassicaudata (Animal Diversity Web)

Kalahari Desert

Source Kalahari Desert (Wikipedia)

King Cobra

Source Animal Diversity Web, University of Michigan Museum of Zoology: Ophiophagus hannah account

Kori Bustard

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Ardeotis kori

Kruger National Park

Source Kruger National Park (Wikipedia)

Little free-tailed bat

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Chaerephon pumilus

Longleaf Pine

Source NatureServe Explorer: Pinus palustris

Mabee's Salamander

Source Wikipedia: Mabee's salamander

Mediterranean Fruit Fly

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Ceratitis capitata

Naja Naja

Source Animal Diversity Web, University of Michigan Museum of Zoology: Naja naja (Animal Diversity Web)

Nilgai

Source NatureServe Explorer: Boselaphus tragocamelus

Northern giraffe

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Giraffa camelopardalis

Olive Baboon

Source Olive Baboon (Wikipedia)

Panamanian spiny pocket mouse

Source Panamanian spiny pocket mouse (Wikipedia)

Pancake Tortoise

Source San Diego Zoo Wildlife Alliance: Malacochersus tornieri

Peacock Butterfly

Source Animal Diversity Web (University of Michigan Museum of Zoology): Aglais io

Pineapple

Source Plants For A Future: Ananas comosus Plants For A Future account

Pteridium Aquilinum

Source NatureServe Explorer: Pteridium aquilinum

Red Admiral

Source NatureServe Explorer: Vanessa atalanta

Reticulated Flatwoods Salamander

Source Wikipedia: Reticulated flatwoods salamander

Robber Fly

Source Asilidae

Rubber Eel

Source Rubber Eel (Wikipedia)

Ruby-throated Hummingbird

Source NatureServe Explorer: Archilochus colubris

Sable Antelope

Source Sable antelope, Wikipedia

Sahel

Source World Wildlife Fund

Savannah Monitor

Source Savannah Monitor (Wikidata)

Serengeti

Source Encyclopaedia Britannica

Sloth Bear

Source Sloth Bear (Wikipedia)

Small hive beetle

Source Animal Diversity Web, University of Michigan Museum of Zoology: Animal Diversity Web: Aethina tumida

Southern Rockhopper Penguin

Source Animal Diversity Web, University of Michigan Museum of Zoology: Eudyptes chrysocome (Animal Diversity Web)

Spotted Hyena

Source Spotted Hyena (Wikipedia)

Striped Hyena

Source Animal Diversity Web, University of Michigan Museum of Zoology: Hyaena hyaena account

Sugar Glider

Source GBIF: Petaurus breviceps

Sunda Pangolin

Source Animal Diversity Web (University of Michigan Museum of Zoology): Manis javanica

Toco Toucan

Source Wikipedia: Toco Toucan

Uebelmannia pectinifera

Source Uebelmannia pectinifera (Wikipedia)

Variable Checkerspot

Source NatureServe Explorer: Euphydryas chalcedona

Vervet Monkey

Source Wikipedia: Vervet monkey

White Rhinoceros

Source White Rhinoceros (Wikipedia)

White-bellied goshawk

Source White-bellied goshawk (Wikidata)

Yellow-footed tortoise

Source Yellow-footed tortoise (Wikipedia)

Showing 51 to 99 of 99 in Home To, page 2 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

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