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Desert Biome

Monument Valley, Arizona

Monument Valley, Arizona (Scott Taylor, used with permission)

Monument Valley, Arizona

Monument Valley, Arizona (Scott Taylor, used with permission)

Format
Let's Talk Science
Readability
5.5

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Learn about the location, plants, animals, human impacts and conservation of the desert biome.

The Terrestrial Biomes

The terrestrial world can be divided into areas called biomes. A biome is a large area of land classified by its plants and animals.

A biome is made up of many ecosystems. An ecosystem is the interaction of living and nonliving things in an environment.

Misconception Alert

An ecosystem is not the same thing as a biome. Biome is the specific geographic area in which ecosystems can be found.

In this backgrounder, major terrestrial biomes of the world are named based on the Whittaker classification scheme.This is not the only classification system because scientists do not all agree on the number and types of biomes. 

Distribution of the Earth’s Major Biomes

The map below shows where each of the eight major terrestrial biomes are located in the world. Canada contains four biomes. These are temperate deciduous forest, grassland, boreal forest/taiga, and tundra. A biome has the same characteristics no matter where in the world it is found. This means that the boreal forests of Canada look like the boreal forests of Russia.

The characteristics of each biome are dependent on its climate. Temperature and precipitation are the most important factors determining what living things can be found in a given biome.

Shown is a colour world map illustrating the location of terrestrial biomes.
Major terrestrial biomes (Let’s Talk Science adapted from an image by Adapted from: H.J. de Blij and P.O. Miller. 1996. Physical Geography of the Global Environment. John Wiley, New York. Pp. 290.).
Image - Text Version

Shown is a colour world map illustrating the location of terrestrial biomes.

The map shows the world's oceans in blue, and its landmasses in stripes and blobs of eight different colours.

A legend on the right side identifies the biomes associated with each colour. Red is labelled "Tropical Rainforest." Yellow is labelled "Savanna." Gold is labelled "Grassland." Brown is labelled "Chaparral." Pink is labelled "Desert." Dark green is labelled "Temperate Deciduous Forest." Bright green is labelled "Boreal Forest/Taiga." Purple is labelled "Tundra."

Starting at the top, purple indicates Alaska, Canada's arctic, the tip of Greenland, Northern Russia, a strip close to the west coast of South America, and part of Central Asia, are tundra.

Below, most of southern Canada and Russia are bright green for boreal forest/taiga.

A gold blob in the middle of North America, another on the southeast coast of South America, a strip in an arc shape across part of the Middle East and southern Russia, a small part of the southeast coast of Africa, and small parts of the west and south coasts of Australia, indicate grassland.

Dark green appears on the west and east coasts of North America, the west coast of South America, large parts central and southern Europe, the UK, eastern Asia, the southeast corner of Australia, and all of New Zealand. This indicates temperate deciduous forest.

Pink areas are across the western United States, northern Mexico, a narrow strip of South America, most of North Africa and the tip of South Africa, Central Asia and the middle of Australia. These indicate desert.

The brown areas are small and scattered widely. They are along the southwest coast of the United States, the northeast coast and southern tip of Africa, most of Italy, Greece and Turkey, and small parts of southern Australia. These indicate chaparral.

Deserts

Location

When looking at a world map, the majority of deserts are along two lines of latitude. The first line is the Tropic of Cancer. This is located at 30 degrees North latitude. The second line is the Tropic of Capricorn . It is located at 30 degrees South latitude. The air tends to be very dry in these regions of the Earth. 

Shown is a world map with areas coloured in shades of orange to indicate three types of arid land.

Deserts of the world (Let’s Talk Science using a public domain image from the U.S. Geological Survey).

Image - Text Version

Shown is a world map with areas coloured in shades of orange to indicate three types of arid land.

A legend in the lower left corner is titled "Distribution of Non-Polar Arid Land (after Meigs, 1953)." It indicates that extremely arid land is deep orange, arid land is medium orange, and semiarid is pale orange. 

The continents are shown in pale green, and the oceans in pale blue. Several lines of latitude are marked across the map, at 60 degrees north,  30 degrees north, 0 degrees, 30 degrees south, and 50 degrees south. 

Staring on the top left of the map, the south western part of North America is streaked with areas of pale orange to the east, and medium orange to the west. Locations in this area are labelled "Great Basin," "Mojave," "Sonoran," and "Chihuahuan."

In South America, the south west coast is marked with a thin strip of deep orange, long blobs of medium orange, and pale areas along the interior. Locations in this area are labelled "Peruvian," "Atacama," and "Patagonian."

A long area of orange crosses the middle of Asia, and another angles down along the west coast of India. This is pale on the outside, and medium inside, with an oval of deep orange in the centre. Locations in this area are labelled "Kara-Kum," "Taklimakan," "Lut," and "Tar."

The Middle East is entirely covered in orange. Most is medium, with a strip of pale across the northwest corner, and an oval of deep in the southeast. The only label in this area is "Arabian."

Much of the northern half of Africa is orange. It goes from pale on the outside to medium, to deep in the centre. The deep orange area is labelled "Sahara" in the west, and "Western" in the east. Below, an area along the east coast is labelled "Somali-Chalbi." 

The southwestern tip of Africa is also orange. Deep along the coast, then medium, and pale in the interior.The deep part is labelled "Namib", and the medium "Kalahari."

All of Australia, except most of the coastline, is orange. Pale on the outside, then medium, then deep in the centre. Locations in the deep orange area are labelled "Great Sandy" and "Simpson."

Some deserts are in landlocked regions. These are places not bordered by an ocean. One example of this is the Great Basin Desert in North America. This is the largest desert in the United States. Coastal deserts form near the coasts of continents. Cold air moves from west to east across oceans. This can create cold foggy weather instead of rain on the western coasts of continents. This happens in the Namib Desert in southwestern Africa and the Atacama Desert in South America.

Description

The difference between deserts is their location and type of climate. Deserts receive less than 25 cm of rain each year. Rainfall is what defines a desert, not temperature. Some deserts receive more rain than others.

Even when a desert does receive rain, the water evaporates quickly. There are few plants, little water and extreme swings in daily temperatures. This makes the soils in deserts rocky or sandy and have very little organic matter. We call these soils aridisols.

Shown is a colour photograph of a landscape of dry, reddish orange soil and distinct rock formations.

Aridisols in Monument Valley, USA (Source: tovfla via iStockphoto).

Image - Text Version

Shown is a colour photograph of a landscape of dry, reddish orange soil and distinct rock formations.

In the foreground, the soil is reddish orange, with a few tufts of dry, pale grasses and shrubs. The land beyond is dry and flat. Along the horizon are rock formations with straight sides and flat tops. They look like huge buildings or towers. The sky above is blue streaked with clouds.

Many deserts also experience a lot of wind. We usually think of deserts as being very hot, but some deserts can be very cold. Cold deserts  are in the Antarctic as well as Greenland. 

Plants & Animals

A desert is often thought of as a windy expanse of sand. But there is more going on in deserts than meets the eye. The plants and animals in deserts have special adaptations. These can help them to live in this sometimes harsh biome.

Plants

Desert plants have found ways to protect themselves in deserts. One way they do that is by reducing the natural evaporation from their leaves. They do this by having small leaves and waxy cuticles . The cuticle is a protective covering on leaves.

Some plants have small or no leaves because the sunlight is so intense. Other plants grow leaves only when it rains and have no leaves the rest of the year.

Plants in the cacti family do not have any leaves. Instead they have prickly hairs or spines covering them. These hairs or spines reduce evaporation. There is also a second purpose for these prickly hairs or spines. They protect plants from desert herbivores . These animals avoid eating the prickly plants.

Plants have also learned how to survive with less water. Like camels, cacti can store water in their tissues to use later.

Shown is a colour photograph of a cluster of green spheres with stripes of yellow spikes.

Golden barrel cacti (Source: Pamla J. Eisenberg from Anaheim, USA [CC BY-SA] via Wikimedia Commons).

Image - Text Version

Shown is a colour photograph of a cluster of green spheres with stripes of yellow spikes.

The spheres are piled together as if they are part of one or two large plants. They are dark green, with pale yellow circles in the top centres. vertical stripes of yellow spikes fan out from the dots, like very thin segments of an orange.

Animals

Animals in hot deserts are good at avoiding the heat. When it is very hot, many animals will only come out at night, when the Sun has gone down. During the day, most animals will find shelter in shady areas. An example of this is the desert scorpion. It hunts at night and spends the day hidden.

Shown is a colour photograph of reddish orange arachnid with two large claws and long, curved tail.

Desert scorpion in Australia (Source: Totajla via iStockphoto).

Image - Text Version

Shown is a colour photograph of reddish orange arachnid with two large claws and long, curved tail.

The animal is on gravel and appears small. It's shell is shiny and varies from dark brown at its claws to pale orange on its back.

To keep cool during the day some desert animals, such as rodents, burrow underground. The rodents in the savanna biome also do this.

In the Sonoran Desert in the United States, prairie dogs are underground most of the time. They build underground burrows that have rooms for different purposes, like sleeping. The burrows they dig provide shelter from the Sun and from predators.

When it is not too hot outside, the prairie dogs come out. When they are above ground, they look for food.

Shown is a colour photograph of two small, furry animals climbing out of a hole and looking at the camera.

Pair of black-tailed prairie dogs (Source: Andyworks via iStockphoto).

Image - Text Version

Shown is a colour photograph of two small, furry animals climbing out of a hole and looking at the camera.

The animals have pale gold fur, and small black claws, eyes and noses. One has its front paws on the front rim of a hole in the soil. The other has one paw and one leg on either side of the rim. Both are looking straight at the camera.

Human Impacts

When humans allow livestock (e.g., cows) to graze on grasslands they turn into deserts. This is called desertification. Population growth and growing cities make this a difficult problem to solve. Other human activities cause damage to desert plants which are slow-growing. Some examples are oil and gas production, urbanization  and off-road vehicles such as dune buggies.

Did you know?

The saguaro cactus takes 200 years to grow to full size!

Deserts and Climate Change 

Climate change is making hot dry places, like the desert, even hotter and drier. This increases the number of droughts. It can also cause watering holes to dry up. Watering holes are an important source of water for desert animals.

As deserts get hotter and drier, wildfires happen more often. This can wipe out the slow-growing plants and replace them with fast-growing grasses.

Shown is a colour photograph of several different sorts of animals in and around a body of water in a dry landscape.

Animals at a watering hole in Etosha National Park, Namibia (Source: FernandoQuevedo via iStockphoto).

Image - Text Version

Shown is a colour photograph of several different sorts of animals in and around a body of water in a dry landscape. 

Black and white striped zebras, gold springboks with white faces and small dark horns, and brown kudus with long corkscrew horns are gathered around calm water. Some are standing in the water with their heads down, drinking. Others are on the dry, rocky land around.

Conservation

There are some solutions that can help conserve deserts. This includes planting bushes and grasses that keep the sand from blowing around. Digging ditches can store rain as well as wind-blown seeds. People are also encouraged to use off-road vehicles only on designated trails.

Shown is a colour photograph of a long, narrow hole, half-filled with water, in a dry landscape.

Ditch in the Chihuahuan Desert, New Mexico, USA (Source: Michael Warren via iStockphoto).

Image - Text Version

Shown is a colour photograph of a long, narrow hole, half-filled with water, in a dry landscape.

The hole stretches from the bottom edge of the image, into the distance. There are dusty dirt roads on each side of the ditch. The land around is dry and pale, dotted with a few small green shrubs. There are low, beige mountains on the horizon, and the sky above is blue, streaked with thin clouds.

In desert cities, such as Palm Springs, California (in the Sonoran Desert) people can get rid of their water-loving lawns.

Instead of lawns, people can plant native desert plants which need less watering. The name for this is xeriscaping.

Shown is a colour photograph of spiky and brightly coloured plants in dry, gravelly soil.

Desert garden with cacti and succulents (Source: constantgardener via iStockphoto).

Image - Text Version

Shown is a colour photograph of spiky and brightly coloured plants in dry, gravelly soil. 

A brown fence runs across the image. Bright pink flowering plants grow against it. On the left is a tall, cylindrical cactus, to the right are two large, round shrubs. One has long, thick, pointed green leaves, and the other has thin. In the foreground are low, rounded plants, some with tiny green leaves, some with thick, grey leaves, and one with tiny pink flowers. All the plants are rooted in pale soil that looks like gravel.

 

Learn More

Deserts 101 | National Geographic (2019)
This video (3:53 mins), from National Geographic, gives an overview of the four major types of deserts. This includes the animals that live there.

Namibia: Live stream in the Namib Desert (Live Feed: Start Date, 2021)
This live cam from NamibiaCam, lets you watch animals visiting a desert watering hole in real time!

David Attenborough: The Fascinating Life Cycle of Desert Plants | Nature Bites (2022)
In this video (5:41 mins), from Nature Bites, David Attenborough explains some of the fascinating things about desert plants.

References

Arizona-Sonora Desert Museum. (2020). Ground squirrels.

McAuliffe, J. R. (2020). Desert soils. Arizona-Sonora Desert Museum.

National Geographic. (n.d.). Desert threats and endangered species.

University of California Museum of Paleontology. (2019). The desert biome.