Desert Biome

1. Desert Biome

2. Desert Biome Locations

3. Desert Biome Misconceptions • Deserts are always hot. That actually isn’t true. During the winter months, some deserts receive snow. Even in the summer months, the temperatures at night can drop by more than 30 ˚ F. 2. The most common plant in deserts are the different species of cacti. Actually, true cacti are only found in the “New World,” though there are plants very much like cacti in some of the African deserts.

4. 3. Deserts are covered primarily by sand. About 30% of the area of the sandiest desert in the world, the Arabian, is sand-covered. Desert pavement (rocky surfaces) and desert soil surfaces of particles finer than sand are much more common 4. Most desert erosion is caused by wind. Actually, most desert erosion is caused by the infrequent rain. Think about out- the Grand Canyon was not made by wind erosion.

5. Desert Characteristics • About 20% of the earth’s surface is covered by desert. • Deserts receive less than10 inches (25 cm) of precipitation per year. • Rainfall is usually very low and/or concentrated in short bursts • between long rainless periods. Evaporationrates regularly exceed • rainfall rates. Sometimes rain starts falling and evaporates before • reaching the ground. • Desert soils are often high in minerals but very low in organic • materials (because there is so little water, dead leaves and grasses • don’t decompose quickly), which makes them poor overall for farming. • Soils range from rocky to sandy. • There are four major types of deserts: 1. hot and dry 2. semiarid (desertification= semi-arid and grassland areas become deserts) 3. coastal 4. cold (Antarctica)

6. Things you probably wouldn’t expect to hear a desert guide say to you: Make sure to bring a warm jacket! • Night temperatures in some deserts can drop as much as 30 degrees F because there is so little water vapor in the air to hold heat. Watch out for the desert flood! • Heavy rains and even spring snow melts can result in dangerous flash floods in dry desert creek beds. It’s not just the heat….it’s the deadly radiation! • Because there is so little water vapor in the air above a desert, the plants and animals of a desert are subject to much higher levels of the sun’s solar radiation. When visiting the desert, wear LONG pants and LONG sleeves, a wide hat, and put sunblock on your face because UV rays can reflect off the desert surface.

7. Hot & Dry (Arid) Types of Deserts The TaklamakanDesert. It’s name literally translates to “those who go in never come out.” The game “Marco…Polo” is based on Marco Polo’s travels through the Taklamakan in the late 13th century.

8. Northern Africa is very different from Sub-Saharan Africa. Most noticeably, northern Africa is almost entirely desert. North Africa is home to the largest desert in the world, the Sahara. How big is the Sahara? It could cover the entire continental United States!

11. The Sahara is one of the harshest environments on the planet. It’s hot during the day, but can be very cool at night. It is enormous. The sandstorms are so fierce they can be seen from space.

12. Massive dust storms that blow out to sea from the Sahara actually play an important role in the development of hurricanes that develop in the U.S. http://www.youtube.com/watch?v=cv4BhZV5mAA

13. Other Hot, Dry (Arid) Deserts….

14. Mojave Desert

15. Sonoran Desert

16. Gobi Desert Temperatures range from well below 0 ̊ F in the winter to over 100 ̊ F in the summer.

17. The Rain Shadow Effect Many deserts are a result of a geographical phenomenon known as a rain shadow.

18. Oregon Rain Shadow

19. The Tibetan Plateau (top), perhaps the best example of a rain shadow. Rain does not make it past the Himalayas, leading to an arid climate on the leeward side of the mountain range.

20. Deserts do support life. Deserts are dominated mostly by reptile species and small mammals such as kangaroo mice. There are few large mammals in most deserts, although there are several types of desert. These animals have adapted to living in this harsh environment.

21. What are some of the ways fauna (animals) have adapted to living in the desert?

22. Dromedary camel-They have a single hump, long legs and a long, curved neck. The hump stores fat, which they are able to draw upon for sustenance; and oxidation of the fat manufactures water. They are desert animals and have numerous adaptations for life in an arid habitat. They have webbed feet (to prevent sinking in the sand); they can close their nostrils and they have a double row of eyelashes to keep out the sand. They can endure long periods without drinking - up to 17 days. When they do drink, they can take up to 136 liters (30 gallons) at a time. By producing dry feces and little urine, they can conserve water. Their body temperature can rise 6-8 degree Celsius before sweating.

23. Some fauna (animals) have developed ways to cool off by positioning their bodies a certain way. Others have evolved body parts to help them cool off. For example, the big ears of the fennec fox help it to release more heat so it can cool off.

24. Jerboa (Asia)

25. Animals are primarily nocturnal (come out only at night) or crepuscular (come out only at dawn and dusk.) http://www.youtube.com/watch?v=cBkWhkAZ9ds desert rain frog-nocturnal Namibia and SA

26. Many animals have body adaptations that allow them to burrow into the sand. Some animals estivate, similar to hibernation except that they are sleeping to escape heat rather than the cold.

28. PRESERVING PRECIOUS WATER • Reptilesrelease very little water in their waste. • Reptiles and insects have thick, tough skin or exoskeletons that prevent • evaporation (water loss).

29. Reptiles like this Diamondback will often spend the hot daytime hours resting in the shade of low-growing shrubs, piles of natural or artificial debris, or rocks. They will also utilize underground burrows of other animals. In the winter, they retreat into caves or similar places to hibernate. http://www.youtube.com/watch?v=bWfslaxznGw

30. What are some of the ways PLANTS have adapted to living in the desert? • Plants in this biome either have very deep tap roots that reach water deeper underground OR they have very shallow, wide-spread roots to suck water up quickly before it evaporates. Desert plants like the mesquite, sagebrush, and creosote bush have deep tap roots that allow them to reach water that is several feet below the surface. Cacti and other succulent plants, on the other hand, have the shallow, wide-spread roots. Cacti are able to take advantage of rain showers by absorbing large amounts of water which they are able to store in their trunks. • The small, waxy leaves of some desert plants/trees like mesquite or creosote bush help slow the loss of water vapor through transpiration. The spines of cacti are actually modified leaves. • Many desert plants and their seeds can remain dormant for long periods of time until the next rainfall. • Some desert shrubs are deciduous, meaning they can drop their leaves so the plant becomes dormant during the driest times of the year.

32. Succulents are desert plants that have thick stems and leaves that can store large amounts of water.

33. Areas where the underground water table is near or even breaks through the surface are known asoasis or waddis (Wah’-dees.) Many ancient camel trade routes were linked together so that it was only a few days travel from one waddi to the next. In areas where the waddi is large enough, ancient trade cities like Timbuktu in the Sahara developed.

36. The Dangers of Water in the Desert People who enjoy camping in the desert know that you never camp close to a dry creek bed. Flash floods can occur and present a life-threatening risk. What makes them particularly dangerous is that they often appear seemingly out of nowhere. It may be blue skies as far as one can see. However, heavy rain 20 miles away can accumulate in these creek beds and several hours later the flash flood may be upon you. http://www.youtube.com/watch?v=rhGgnr44SVI

37. Semi-arid Deserts The word “arid” means “dry.” Semi-arid deserts receive more precipitation than arid deserts and can therefore support larger communities of plants and animals. Semi-arid deserts frequently have a very long dry season and a brief rainy season. Semi-arid deserts are frequently located on the edges of hot, dry deserts where the biome is transitioning from hot desert gradually into a grassland biome. The African Sahel region is one of the best examples of this.

38. The Sahel region also offers one of the best examples of the process of desertification, the geological process where grassland is changing into desert.

39. In good times.

40. In bad times. An abandoned village in the Sahel. http://www.youtube.com/watch?v=tDWS6AzEkE0

41. Review

42. What primary factors determine the type of biome that can become established in a geographic location? • Average annual temperatures • Latitude • Annual Precipitation • Altitude

43. Which biome indicates the location of desert biome? Areas marked by #4

44. What are several types of adaptations that enable animals to survive in the desert biome? • Thick, tough skin or an exoskeleton to slow water loss. • The ability to burrow to escape the heat of the day. • Releasing only minimal amounts of water in waste. • The ability to hunt or feed at night. • Wide, spreading feet that make walking on sand easier. • The ability to survive primarily from the small amount of water that is in the food the organism eats. • Large ears to dissipate heat.

45. Which plant adaptations would be best suited for life in a desert biome? • Small waxy leaves to prevent water loss through transpiration. • Widespread roots to absorb water quickly before it evaporates. • Deep tap roots to reach groundwater.

46. While driving his Jeep through the Sonoran Desert in the middle of the day, Rubin complains that he hasn’t seen hardly any animals roaming throughout the cacti and other vegetation. What is the most likely explanation for the lack of animals? • Most of the animals will be in burrows or in shade during the day.

47. The most important limiting factor in any terrestrial biome is the amount of precipitation the area receives.

48. What is desertification and what are some of the factors leading to desertification? • The process where an area of grassland gradually transforms into deserts. • Climate change • Overpopulation (carrying capacity exceeded.) • Overgrazing