Write in your notes: I can describe the characteristics of Earth’s terrestrial Desert biome.

Desert Biome

Desert Characteristics About 20% of the earth’s surface is covered by desert. Deserts receive less than 10 inches (25 cm) of precipitation per year. Rainfall is usually very low and/or concentrated in short bursts between long rainless periods. Evaporation rates 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 (Sahara) 2. semiarid (desertification= semi-arid and grassland areas become deserts) 3. coastal 4. cold The largest cold desert on Earth is Antarctica. The largest hot desert on Earth is the Sahara.

Northern Africa is very different from Sub-Saharan Africa. Most noticeably, northern Africa is almost entirely desert. North Africa is home to the Sahara. How big is the Sahara? It could cover the entire continental United States! Hot and dry (arid)

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.

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. ube.com/watch? v=cv4BhZV5mAA

The Kalahari Desert Some areas of the Kalahari are semi-arid desert. Semi- arid deserts receive more annual precipitation and support larger populations of plants and animals. xU

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

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.

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

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.

Jerboa (Asia)

Animals are primarily nocturnal (come out only at night) or crepuscular (come out only at dawn and dusk.) 9ds desert rain frog-nocturnal Namibia and SA

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.

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

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. Gw

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.

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

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.

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.

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

In good times.

In bad times. An abandoned village in the Sahel.

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

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

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.

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.

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.

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

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