2. What is a desert? Deserts can be hot or cold but they are always dry. They receive less than 25 cm of precipitation annually. They cover 22 million km 2 or 1/5 of the earth’s surface. There are four major types of deserts: Hot and dry, Semi-arid Coastal Cold Deserts are formed by mountains blocking the path of precipitation

3. Deserts Around the World: Some of the major deserts are: Sahara (Africa) Great Basin (North America) Atacama (South America) Mojave (North America) Great Victoria (Australia) Antarctic (Antarctica) Arabian (Asia) Patagonian (South America) Great Sandy (Australia) Gobi (Asia)

4. North American Deserts: There are four North American deserts : Great Basin, Sonoran, Mojave, and Chihuanhuan. They are all in Mexico and South Western U.S.A.

5. Desert plant life: There are around 2000 different species of cactus, and 6000 different types of plants in the desert. Cactus can live for anywhere between 50 and 200 years. Palm and olive trees found in the desert can be a source of food for humans.

6. Desert plant life:

7. Desert animal life: There are around 1500 different types of animals living in the desert. Almost all of the animals living in the desert have adapted to be able to better survive in the desert. World-wide there are 17 species of penguin, all of which live in the Southern hemisphere

8. Desert Animal Life:

9. Human Impact: Humans in many ways can affect or pollute deserts. If they do not use the deserts properly,then the desert ecosystem will become unbalanced. Examples are off-road vehicles that would impact the deserts (e.g., atv, snowmobile, and dirt bikes). Humans don’t only affect the desert they also affect the desert wildlife, by killing rodents or predators that invade farms. Most deserts support fragile ecosystems that are easily damaged by roads. Humans pollute desert ecosystems with mineral refuse, or oil contamination that can come from industries or mines. Humans also destroy water supplies by culverting or diverting water supplies, which are already likely scarce, which can prevent infrequent rainfall from reaching the native plants. Humans positively impact the desert by irrigating water to the desert biomes, and allowing the to thrive. Also when humans make farms they plant gardens which help out the ecosystem.

10. Threatened Species and Conservation Programs: Threatened Species is a population of organisms that is at risk of becoming extinct because it is either few in numbers or threatened by changing environment or predation parameters. There are many threatened species like the Bald eagle, the Desert Pupfish, and the Desert Tortoise that are threatened in our deserts. The Desert Tortoise was listed as a threatened species, April 2, 1990 by the “US fish and Wildlife Service”. The “US fish and Wildlife Service” has its own a threatened conservation program that provides Wildlife health checks to animals that are living with high populations, low populations, threatened species, and Endangered species. The WWF (World Wildlife Fund) has many conservation projects that help out with threaten species in our deserts.

11. Adaptation to Abiotic Factors: Desert plants and animals have adopted special adaptations to survive in the harsh desert conditions. There are 3 ways plants and animals survive the heat: Expire( die but leave behind seeds), Evade ( beat the heat by staying out of it), Endure (deal with the heat). There are many ways to save - water plants and animals can both store, conserve or tolerate the lack of water. They also reduce their heat input by staying out of the sun, dissipate heat by evaporating their body heat or tolerate the extreme heat. Animals have adapted in different ways than plants. Animals can make burrows to escape the heat. Some animals come out of their burrows in the morning and late afternoon to avoid the hottest part of the day. Others who cannot take much heat at all only come out during the night. When the heat becomes so hot and it is so dry a lot of animals will estivate, which is the same as hibernation, but the animal’s escaping heat not cold. Plants adapt to the heat by slowing down their growth to conserve energy and water needed to feed their entire bodies. Many cacti and some plants can store enough water in their stems or leaves to get the through the hottest and driest parts of the year. With the plants roots, they can be either very short (2.5 centimeters) to get all the dew and moisture from the top soil or very long (30 meters) that can tap into underground aquifers. Plants and animals have found numerous adaption's to help them survive and they will find many more.

12. The largest desert in the world is the Sahara – 9 million km 2 (greater than Australia) Antarctica is classified as a desert. Gobi desert in Asia is cold for most of the year. Atacama desert in South America is the driest desert in the world, because it is surrounded by mountains on 2 sides. Some parts have never received rain.

13. Bibliography http://library.thinkquest.org http://blueplanetbiomes.org http://wc.pima.edu http://answers.yahoo.com/ http://wiki.answers.com/ http://wwf.ca/ http://.fws.gov/