Have you ever heard of a biome? Do you know what a biome is? A biome is a large region characterized by a specific type of climate and certain types of plants and animal communities. For my group, we are doing the desert biome.

Deserts are areas that receive less than 25 cm of precipitation a year and have little or no vegetation. Because of this, there is one main characteristic that all deserts share, and that is that deserts are the driest places on earth.

A Desert
A Desert

Geography


Deserts take up one-third of the Earth's land surface. The temperatures in deserts vary seasonally, with high daytime temperatures in the summer going as high as 113 degrees F or 45 degrees C, and also low nighttime temperatures in the winter going as low as 32 degrees F or 0 degrees C because of the humidity. One use of water in the deserts is to trap “infrared” radiation from both the sun and the ground, and dry desert air is incapable of blocking sunlight during the day or trapping heat during the night. Because of this, all of the sun's heat reaches the ground. As soon as the sun sets the desert cools quickly by radiating its heat into space. If you have noticed, deserts are usually always located near large mountain ranges because mountains can block the passage of moisture-filled clouds, which limits precipitation. If you visit a desert you may come across Sand dunes (ergs) and stony surfaces (Hamada surfaces). These make up a minority of desert surfaces. Minimal soil development and vegetation rarely occur because of the exposures of the rocky terrain.


Wherever you see yellow or orange, that is the location of a desert
Wherever you see yellow or orange, that is the location of a desert

Edited by Brittney B


Goods/ Services/ Uses of a desert


You may not realize it, but there are many valuables in the desert. These valuables including minerals such as gypsum, copper, gold, silver, chromite, uranium, lead-zinc, and much more. Deserts are not ideal places to live, but one good thing about them is that they are also ideal places for artifacts and fossils to be preserved.


Edited by Brittney B


Climate


Dry Tropical Climate

The dry desert is in Köppen's BWh climate category. This means it is a Low Latitude climate. The B stands for Dry Desert climates. Every month have average temperatures over 64° F (18° C). The W stands for desert climate and the h stands for dry and hot, with average yearly temperatures over 64° F (18° C).

Dry Desert climates are formed by high-pressure zones in which cold air descends. Then the descending air becomes warm but, instead of releasing rain, the heat from the ground evaporates the water before it can produce as rain. The ground is hot from the sun’s rays beating down on it from above. There is not a lot of atmosphere to protect it from radiant energy.

There is approximately 1 in. (.25 cm) of rainfall in dry deserts per year. The average yearly temperature is 64° F (18° C).
The latitude range is 15-28° north and south of the equator. Deserts cover about 1/5 of the earth, these deserts consist of: Sahara, Sonora, Thar, Kalahari and the Great Australian.

Plants of the Dry Desert have learned to live with the lack of water by using dew for moisture and using the water through their leaves and stems.

Dry tropical climate of a desert
Dry tropical climate of a desert

Arid, and Semi-Arid Desert


Arid deserts mostly occur at low latitudes, and can be found in North America, South America, Africa, and Southern Asia.

Seasons in the arid desert are generally dry and hot, with few occurrences of rain during the winter. The heat peaks to extremes during the daytime because there are no clouds to shield the earth from the sun's rays.

When it does rain, it sometimes doesn’t even get a chance to hit the ground and its evaporated. The soil is usually sand or coarse, and rocky. The vegetation consists mainly of shrubs and small trees, which the leaves are made to hold water. Most desert life forms have learned to be active at night being the temperature drops and its not so hot.

Semi-arid deserts are found in North America, Europe, Russia, and Northern Asia.

Seasons are more defined than in the Arid desert, with low rainfalls during the winter. Rainfall is rare, several species of animals and plants thrive in this climate, the animals, are nocturnal, they can still be found during the day, but mostly in the shade of the few trees and plants.

An arid or semi-arid climate of a desert
An arid or semi-arid climate of a desert

Coastal and Cold Desert


Coastal deserts are found in areas that are fairly warm to cool, such as the Neotropic and Nearctic territory. The winters are usually cool and short, while the summers are long and warm. The soil is mostly sandy with a high alkaline content, its also very absorbent, so rain seeps rapidly into the ground. Most of the vegetation in the coastal desert features thick plant life, with good water preservation, and their roots are close to the surface of the ground to get as much water as they can before it drains into the soil.
Cold coastal climate of a desert
Cold coastal climate of a desert

Edited by Amber T




Animals


The armadillo lizard is a type of lizard living in the desert. It has protection all over its body to protect its underbody. The Armadillo lizard can be found in the deserts of the southern tip of Africa.The body length is 15-17 inches, the tail is 14-16 inches long, and it weighs 8-17 lbs. The head, body, and club-like tail are all flattened, enabling it to wriggle easily into rock crevices for shelter. It may also adopt a curious defensive posture when threatened by rolling itself up like an Armadillo, with its tail tightly held in its jaws, presenting a spiny ring to the predator and protecting the softer, vulnerable belly area. That's why its called the Armadillo Lizard. The armored Armadillo Lizard has protection all around its body so that predators can't harm any of its under parts. Also squeeze into small places for escape. Another protection is their spiny scales that go all the way around its body. Their tails and spines also can be used to defend themselves as well. The Armadillo Lizard can be found in the deserts of the southern tip of Africa.

The Armadillo Lizard has its babies in the late summer. Only 1 or 2 babies are born during that time. The Armadillo Lizards stay in family groups, and they will all live in the same rock crevice. When the lizards give birth, the babies are live-born, but do have a thin membranous shell that they need to break through.

The Armadillo Lizard is a prey animal. It is preyed upon by bigger and stronger predators, such as humans, etc. The Armadillo Lizard's armor is most useful against many birds, mammals, and other reptiles. The Cape Provincial Ordinance helps the Armadillo Lizards when their injured or sick. That way the Armadillo lizards can be less endangered.

The armadillo lizard
The armadillo lizard
The Banded Gila Monster can get to be 2 feet long and can weigh up to 3 pounds. They have a big head, fat body, and a thick, short tail. Its skin is dry because it lives in the desert and can't afford to lose fluids. The skin is bumpy. The Banded Gila Monster is mainly found in the Mojave Desert. It is named for the Gila River Basin, which is found in the southwestern United States. The Banded Gila Monster spends most of its life alone, but they do gather together during mating season.

The Gila Monsters venom is about as strong as a Western Diamondback Rattlesnake.
The Gila Monster eats bird and reptile eggs, young rodents and small reptiles, baby birds, rabbits and hares. They can eat huge amounts of food at one time and they can store fat in their tails and their bodies.

The Gila Monster is a predator. Sometimes it digs its own holes and some times it uses holes dug by other animals for their burrows. They live in heavy brush, or rocky brushy wash bed or canyon bottoms.

The gila monster
The gila monster
The average bobcat weighs 15 to 20 pounds, and is 2 feet tall and 3 to 4 feet long. The bobcat looks pretty much like a regular cat except bigger. The desert bobcat's color is a mixture of white, black, brown, and orange.

Bobcats can be found almost anywhere, but one of the most common places is the southwest desert. They like it there the most because of the bushy, and rocky terrain. The bushes give shade if it's hot, and the rocks are a perfect hiding spot if they're hunting prey. The bobcat's diet consist of rabbits, squirrels, mice, gophers,rats, and fish. They're good at catching all their prey because of their hunting ability.

A bobcat's mating is a lot like a regular house cat's mating. That's one similarity that they have. Bobcats will have one litter of kittens a year. A litter of bobcats consists of 2 to 3 kittens. When food is scarce, a bobcat will not have a litter at all.

Despite the bobcat's cute appearance it is actually very fierce and can kill animals as large as deer. A good thing about the bobcat is it won't kill any healthy large prey unless it's desperate.

Bobcats are loners. Each bobcat has its own territory which it will not share with other bobcats, except for females.
The bobcat's status in the wild used to be very plentiful, but too many people took advantage of that and almost killed them off. A good thing now is that the big game people are protecting them.


A bobcat
A bobcat
The Cactus Wren lives in the arid and semi-arid deserts of southwestern United States and the chaparral of southern California and northern Mexico. The California chaparral has hot and dry summers and humid and cold winters. It normally gets about 6 inches of rain per year.
At 7-9 inches long, the Cactus Wren is the largest wren in the United States. Both sexes look alike. Both are brown and have a white stripe running over each eye.

They are very active and curious birds. They quickly investigate anything new in their territory. If you leave your car windows down or the garage doors open they are sure to enter and check it out thoroughly.

Cactus Wrens don't migrate and are considered permanent residents of the region they live in. Males will vigorously defend their territory throughout the breeding season.

The Cactus Wren mainly eats insects like ants, beetles, grasshoppers, wasps, fruits, seeds, and and sometimes a treefrog or lizard. It will sometimes eat seeds and fruit. It has adapted to its hot habitat by shifting its foraging behavior according to the temperature. It begins to forage on the ground, and in the branches of shrubs in the late morning.
The cactus wren
The cactus wren
The coyote has large, pointed ears and a bushy tail. Coyotes are known for their sharp eyesight, keen hearing and a keen sense of smell. Adult coyotes can grow to be 4 feet long (including the tail which can be 11 - 16 inches long). They can be 2 feet tall and weigh up to 30 pounds.

Coyotes once only lived in Western America, but people have forced them to find other habitats. Coyotes can be found in the United States, Canada, and Mexico. They live in all kinds of habitats including deserts, prairies and mountains. Coyotes have even been found on Cape Cod.
Coyotes eat mostly rabbits and rodents. They also hunt antelope, goats, sheep, and other animals. They will eat insects and reptiles. Dead elk and deer, as well as cattle will become the main food in the northern wintertime. Coyotes will also eat fruits and nuts.

Most coyotes live alone or in pairs. They might live together in larger groups. Coyote families guard and mark their own areas.

Coyote's coloring help it to hide in the desert and hunt for it's prey. Coyotes will eat almost anything available to them where ever they are; fruits, rodents, small animals, and garbage. Coyotes are clever animals and adjust to their environment.
A coyote
A coyote
Desert bighorn sheep is a subspecies of the Rocky Mountain bighorn sheep. It's preferred habitat are steep slopes on, or near mountains, with a clear view of the surrounding area. They have excellent eyesight and can spot predators from a long way off. They exist in a barren, mostly waterless environment in the Mojave and Sonoran deserts on the North American continent.

The desert bighorn sheep have a solid, stocky, and muscular body on short legs. They are not as stocky as the Rocky Mountain bighorn, and their horns are flatter and spread out more from their heads. The horns can weigh as much as 30 lb. Their muzzle is narrow and pointed, while their ears are short. They have very acute eyesight, which helps them gage distances when jumping from rock to rock. Their sharp-edged cloven hooves are elastic and concave. Their coat is smooth and made up of an outer coat of stiff guard hairs and a short, wavy undercoat.

The males, or rams, have huge brown horns with horizontal ridges. They curl back over the ears, down and up again past the cheeks. The females, or ewes, have smaller horns that never get larger than half a curl.

The average life span of a desert bighorn is approximately 9 years. Most sheep live for more than 10 years, except when they become overcrowded, in which case their life span is only 6-7 years. The females are led by an old ewe. Young females will usually stay with their mother's group, but the males leave when they are 2-4 years old to join a group of rams.
Bighorn sheep
Bighorn sheep

The kangaroo rat lives in the desert scrub of the Mojave and Sonoran deserts of California and Arizona, and western through southern Nevada. These are the most arid desert regions in the United States.

They live in large dens with wide openings which they dig themselves at the base of bushes. It spends most of its day underground sleeping, and comes out to feed at night when it is cooler.

external image The%20Morro%20Bay%20kangaroo%20rat-w-text.jpg The kangaroo rat moves exactly like a real kangaroo, but is not a real kangaroo. It is actually a rodent. They drum the ground with their hind legs and kick sand at objects, probably to see if it’s alive.

The kangaroo rat mostly eats seeds, leaves, stems and insects. It has adapted to desert life by getting its water from the food it eats. Another great adaptation the kangaroo rat has is a cheek pouch, which it can store food in for weeks while finding shelter. Another is its big, long, fluffy tail. It uses its tail for balance and steering its way.

The Desert Tortoise can be found in the Mojave and Sonoran Deserts of southern California, two of North America's four deserts.

Its front legs are muscular and flattened with long claws, and are very well adapted for digging deep burrows. Desert Tortoises can make hissing, popping, and poinking sounds, usually out of fear or distress. Its domed, brown shell can grow to be 9-15 inches in length, 4-6 inches high, and the tortoise can weigh from 8 to 15 lbs. They usually live to be about 80 years, but some have been known to be a 100 years old.

To escape the heat of the summer and the cold of winter the desert tortoises live in burrows which they dig. Some of them can be three to six feet deep. They will spend November through February in a torpid state in their underground burrows. Some burrows have been used for over a hundred years. 95% of a tortoise's life is spent underground. Their most active time is in the spring when they will forage for herbs, grasses, new growth of cactus and annual flowers.
A desert tortoise
A desert tortoise
The javelina is the only wild pig in North America. It looks exactly like a real pig except a little bigger. It is a grizzled blackish-gray color with a yellowish band which runs under the neck. It has small, round ears and beady eyes. Its body is barrel-shaped with short legs. The javelina grows from 46 to 60 inches long, and can weigh up to 60 pounds.

Javelinas live in the canyon area of the desert. They live there because it is bushy and there are water holes everywhere. They need the bushes for the shade and they need lot's of water to live.

The javelina eats cacti, grass, bulbs, berries, flowers, mushrooms, and fruit, which is easy for them to get in their habitat.
The javelina always travel and live in groups. The female gives birth to twins about once a year. Her young travel with the group their whole life until they die. No new members are ever accepted into the group unless they are born into it.

The javelinas have a very good nose. That can have its advantages if there is a predator around. They also look for food in groups so if they're attacked they can fight back in numbers.

The javelina's niche is the water holes and bushes in the canyon area where they live. They get shade under the bushes, so they won't over heat. They can't survive long without water, so it's good to have water close by if you are a javelina.
A javelina
A javelina
Pronghorn Antelopes are native to America and are found nowhere else in the world. They are the last surviving member of the Antilocarpidae family. Once they were as abundant as the buffalo. But by the 1920s only about 13,000 animals remained. Due to conservation and range management there are now about 500,000 pronghorns in the United States and Canada.

Part of this dwindling population consists of the Sonoran Pronghorn Antelope, a desert sub--species of the pronghorn. Only about 480 animals remain in North America and they are on the brink of extinction. They are found only in two small areas of the Sonoran Desert of southwestern Arizona and northern Mexico.

Smaller than a white-tailed deer, the Sonoran pronghorns stand less than 3 feet at the shoulders. Their overall body length, including their short tail, is 48 to 57 inches. Males can weigh 90 to 130 lbs. and females 75 to 110 lbs. Females are about 10% smaller than the males. The upper part of the Sonoran pronghorn is a rich tan color.

4 pronghorn antelopes
4 pronghorn antelopes
The strangest of lizards is the Thorny Devil. This is the only species in its genus. The lizard's body has conical spines all over, including spines above each eye and a hump behind its head which is spiny. The tail is also spiny. Its spines make it easy to identify. The color changes on the Thorny Devil's body from yellow to reddish brown to black, depending on which type of soil it is crossing. They change colors to be camouflaged and makes it easier for them to hide.

The total length they can grow is 20 cm. This lizard is a harmless reptile. When the lizard walks, the lizard's tail lifts and it walks in a shaky way. People say its a slow moving creature. The Thorny Devil is found in Western Australia, and North and South Queensland.
The Thorny Devil lives for about 20 years.

The Thorny Devil is one of the least aggressive reptiles. It likes to defend itself but has weird ways of doing it:
1) They have the ability to change colors to match their environment.
2) They hide in small shrubs.
3) When they're scared they put their head between front legs, which shows a fake head or knob on its neck in the place where a normal head should be. 4) If a predator tries to flip it over it puts its spine and curved tail against the ground to prevent it from falling over.
5) Its movement looks like a leaf, and it often "freezes" instinctively.
6) They have the ability to puff themselves up like a ball, which makes them look bigger.

The Thorny Devil usually eats ants, eating a very large number of ants in a single meal, about 600 to 3000 ants! They can only eat one ant at a time with their sticky tongue, but can eat at a rate of up to 45 ants a minute.
The Thorny Devil is a prey animal, because it's a small, slow moving creature. Their worst predators are humans and Bustards (a type of bird). The Thorny devil has to be careful about the Bustards, because it can just swoop down, and at least hurt it. The Bustards is found on many continents, and is the size of a chicken.

The Thorny Devil is an endangered animal. People have been saving the Thorny Devil's nests and eggs by placing wire enclosures around the nests. By doing this they are keeping predators out and hold the babies in after hatching. This technique seems to be working.
The thorny devil
The thorny devil

Edited by Corey L



Vegetation


Shrubs are dominant in the deserts and are either evergreen or deciduous. They usually have small leaves, and often have thorns or spines, even possibly aromatic oils. They have shallow roots because there is little precipitation each year.
Desert shrubs
Desert shrubs
Lithops commonly known as ‘living stones’ mimic the sands and stones around where they grow. They can go months without water by storing it within their thick leaves. In periods of droughts their leaves shrink beneath the soil.
Lithops
Lithops
Most of the vegetation in the desert space out from each other to prevent competition for water. In fact there are some plants that have special chemicals and poisons in their roots to stop things from growing near by.

Some plants have roots that both reach down deep and are rather shallow. Yet others slow down their growth rate for the drier part of the year and some direct the shiny side of their leaves toward the sun to help reflect its rays away.


Edited by Harry P



Current/Major Stresses-Human Impacts on Desert


The desert is unfriendly to human life. Because of this it has been preserved from being overrun by things that could destroy it.

Use of Plant and Animals
The human impact on the desert was not severe as long as traditional lifestyles remained. Many desert dwellers understood that they needed to keep a balance between themselves and the desert environment. Many desert dwellers used plants and animals for food, but they did not over use them. The amount that was used could recover. In modern times plants and animals are threatened because of the firearms and the increase in population. Popular desert plants and animals are threatened because they are now being sold at high prices. Lizards and cacti are a couple of items being sold. This is a type of desertification. Desertification is the loss of plant life. Humans are taking desert plants away from their natural environment to make money off of them.

Natural Resources
Since the population is growing and some places are over populated the amount of natural resources are decreasing. The water tables in many desert regions have dropped because of the amount of wells being added. Supplies of oil and minerals are being removed from underneath the desert surface. These oils and minerals cannot be replaced.

In earlier years crops were able to grow in desert environments due to the aid of irrigation. In modern times, dams and machinery help control the rivers and irrigation systems. This allows farmers to settle in desert environments. Irrigation must be controlled because if too much water is pumped, water will be used fasted then it can be replaced.

Quality of the Environment
The desert environment has been impacted by humans in several different ways. Roads are required for humans to drill for oil and mine for other resources. Since people are drilling and mining they need houses to live in. Most of these changes have occurred along the Mediterranean. Deep centers in the deserts are usually not disturbed. Since the world’s climate may be changing due to human activity, the desert climate may change too.

Human Impact on Biotic Soil Crusts
A biotic soil crust is a community of fungus, algae, lichens and mosses.

Soil Nutrients
Biotic soil crusts are important in a desert environment because nitrogen is often limiting. The soil crusts can fix the carbon and nitrogen in the atmosphere. Carbon fixation happens when the photosynthesizing of lichens and cyanobacteria happens within the crusts. Disturbance of the soil crusts results in a significant loss of nitrogen content within the soil. Activities such as shallow raking, deep raking, one pass with a tank, ten passes with a tank, and scalping (removing the top centimeter of soil) decrease the amount of nitrogen in the soil. Chlorophyll contents in the crusts recover quickly if the disturbance leaves the disturbed crust in place. Human disturbance in arid-semi arid environments reduce the fertility of desert soils.

Soil Stability and Water Retention
Biotic desert crusts are important in the stability of deserts because they are more resistant to wind erosion than sand. Lichen is an important component of soil crusts because it has a high water holding capacity. Photosynthesis of lichen is improved due to the high water holding capacity because it is water dependent. Wind erodibility of the soil is increased by the disturbance of soil crusts. Soils that had undisturbed crustal development are the only soils that are able to withstand high wind speed in the desert.

Desert area after extensive disturbance to the soil crusts.
Desert area after extensive disturbance to the soil crusts.
A healthy undisturbed desert ecosystem
A healthy undisturbed desert ecosystem

Edited by Nicole F



Sources

Information:

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http://www.runet.edu/~swoodwar/CLASSES/GEOG235/biomes/desert/desert.htmlhttp://www.runet.edu/~swoodwar/CLASSES/GEOG235/biomes/desert/desert.htmlhttp://www.runet.edu/~swoodwar/CLASSES/GEOG235/biomes/desert/desert.html

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http://en.wikipedia.org/wiki/Desert

http://en.wikipedia.org/wiki/Deserthttp://en.wikipedia.org/wiki/Desert