Liz Stillman Juliette Langley Phoebe Staab Victoria Jukic Emily Carlo DESERTS.

Liz StillmanJuliette LangleyPhoebe StaabVictoria JukicEmily Carlo

DESERTS

Hmm, I wonder what a desert is?

Funny you ask that! Deserts cover 30 percent of earth's surface, yet not many people know alot about this biome. To be sophisticated, a desert is: 

"An area where evaporation exceeds precipitation"  

Where do deserts exist?

General Biodiversity- Producers

Blue-Green Algae • Make food through photosynthesis • Survive as spores and come to life during rain 

 Fungi• Obtain nutrients from dead matter • Parasitic form that leeches onto green plants or help them

absorb nutrients• Reproduce as spores • Lichens 

Algae and fungi living together • Fungi surround algae cells• Live on desert rocks 

Green Plants  • Only available nutrients: nitrogen, phosphorus, potassium • Require hard trunks to keep upright, even with loss of

water• Waxy leaves to keep in moisture• Smaller leaves so less direct sun 

1.Cacti  Spines Soft spongy interior to hold water Photosynthesis happens in trunk

     2. Woody Shrubs and Trees 

Small leaves Spines to protect from animals  Wide root system Sage brush, salt brush, cresote,

mesquite, joshua trees       3. Palms 

Produce dates which support a lot of species

Can grow in soil with high salt content ahigh heat

Annuals• Long grasses• Appear after seasonal rains 

General Biodiversity- ConsumersInvertebrates • lack backbones• termites, locus,spiders• primary consumers 

 Amphibians• frogs and toads• eat tadpoles during rainy season 

 Reptiles• snakes and lizards• cold-blooded so can survive• sticky tongue for catching insects

 Birds• migrate to the desert• ground birds- eat plants and insects

(parakeet) • birds of prey- eat small mammals

(owls) Mammals • rabbits- herbivores • kangaroos- herbivores• camels- herbivores   • hyenas- carnivores

Overview

Different Types of Deserts 

Temperate Desert

Known as the "hot" desert• Subtropical• Soils are course-textured, shallow, or gravely

o Coarse b/c of chemical weatheringo Fine dust and sand are blown away- leaving heavier

pieces behindo  good drainage and have no subsurface water.

• Plants are mainly ground-hugging shrubs and short woody trees.

Temperate Desert Biodiversity

Plants (Prickly Pear and Saguaro Cactus)  • Reduction of leaves• Photosynthesis in stem• Store mass amounts of water•  Waxy coating 

 Animals (Bactrian Camel and Zebratail Lizard) • Nocturnal lifestyle• Live in burrows• Slender bodies and long limbs• Waxy body coating• Protective eyelids from sun• Efficient kidneys

Tropical Deserts • Known as the most extreme of the deserts•  Rainfall is sporadic, sometimes years without a

drop•  Found in the subtropics

o found within 25°-40° latitude• Have the highest annual average temperature on

Earth •  Skies remain cloud free

o causes insolation- lets warm air escape at night

•  Consists of sand dunes and minimal biodiversity

Tropical Desert Biodiversity

Plants (Acacia trees and Palms) • Low to the ground

o less wind= less water loss• Store water trunk• Root spread horizontal • Small leaves

Animal (Dromedary Camel and Cheetah) • Light colored• Live near plants for shade • Nocturnal • Smaller

  More aquatic animals

Polar Deserts• Nearly all moisture in the air is in the form of ice• Mostly bedrock or gravel plains• Snow dunes are in areas where precipitation is more

abundant• Water continually freezes and thaws and creates texture

on the ground• Most common during ice ages • During the warmest month the mean temperature is 10 C

Polar Desert Biodiversity

Plants (Saxaul Tree and Tamarix)• Small shrubs and grass• Store water in trunk• Survive high salt content 

  Animals (Snow Leopard and Golden Eagle) • Dark fur• Store water • Fur for insulation

Tropical vs. Temperate vs. Polar • Hot and dry most of

the year•  The sky is cloud

free• Hard surface

o Rocks and some sand

• Hot in day & cold at night

• Gravely Soil• Ground-hugging

shrubs 

• Cold• Icy•  Summers are

warm

• The two main factors that determine climate are both the temperature and precipitation.

• The elements of secondary importance to defining climate are winds, humidity, air pressure, and sunshine versus cloud cover.

Climate

Climate 

• Different climates lead to different communities of organisms, especially vegetation.

 • Each biome contains many ecosystems whose communities have adapted to

differences in climate, soil, and other environmental factors.

• Climates change over the earth’s history.

• Temperature, precipitation, and soil type are the most important factors in producing the type of biome.

Preciptitation

• Deserts are the world's driest regions. 

• These climates receive less than 10 inches of rainfall a year. 

• Often, precipitation over lands take streamers of water that evaporate into the dry air before they even reach the ground.

Temperature

• The daily temperature in deserts fluctuates

• The reason for this fluctuation is that little humidity is available to absorb incoming sunlight during the day and there is virtually no cloud cover to trap the heat escaping from the surface at night.

• Deserts come in hot and cool varieties. 

Hot Deserts: Temperature

• Hot deserts, are the hottest places on Earth.

• Hot deserts, daytime temperatures reach between 105 and 115°F and occasionally exceed 120°F.

•  At night it cools off to around 75°F. Occasionally, during the winter the temperature at night drops below freezing.

• The world's hot deserts are located in the subtropics between 15° and 30° latitude north and south.

Cool Deserts: Temperature 

• Cool deserts, afternoon temperatures in summer reach 105°F.

• However, it is not uncommon for nighttime temperatures in winter to dip below 30°F.

• Cool deserts, on the other hand, have an annual mean temperature below 65°F and, for at least one month out of the year, a mean temperature below 45°F.

Humidity 

• Humidity is the average amount      of water vapor in the air. • Lack of humidity is particularly

     because hot areas can hold so      much moisture. • Deserts have long periods of little to no rain

 before receiving short bursts of precipitation, but the amount of humidity that enters the air is rare. 

• The desert air is so dry that the rate of evaporation exceeds the rainfall rate, and the rainfall may evaporate before it hits the ground.

• Average humidity within deserts: 10% - 40%

Winds• Global air circulation is

affected by the rotation of the earth on its axis.

• Atmospheric regions called cells are made from belts of major winds continuously blowing) that distribute heat and moisture

• Coriolis effect -------> 

Sunshine vs. Cloud Cover• Except during dust storms, the atmosphere of a desert is

very clear with a rare occurrence of clouds.• Because of the lack of cloud cover the incoming solar

energy reaches a maximum. • Throughout the night, air temperature decreases rapidly,

because there is little counter radiation from clouds. • Another consequence of sparse cloud cover is that after rain

water in the soil surface evaporates quickly. 

Human Effect On DesertsDeserts of North America

Sonoran Desert-populated desert in north america-Tuscon and Phoenix -use canals and underground irrigation systems that have destroyed or degraded an estimated 90 percent of desert raparian areas like the Gila River.  Great Basin Desert-around 1900, humans introduced a new "cheat grass" that allowed for the sagebrush to be ignited on fire, and thus destroyed, helping agriculture without killing the grass roots. 

Human Effect on DesertsDeserts in South America

Atacama-Initial human occupation coincided with a change from very dry environments to humid environments. - associated with drying of the lakes. 

African DesertsSahara-through the process of desertification, the Sahara has been slowly claiming the arable land in Northern Africa. - Modern technology, such as the building of the Aswan Dam, has attempted to halt this process, and has met with some success

Human Effect On DesertsAsia

Arabian - Extreme heat prevails all throughout the day, while nights are freezing cold in this desert. -unsuitable for human habitation.Gobi-acted as a barrier to both invasion and cultural diffusion- forced most of China's people to live in the more fertile east, as no good farmland exists- fantastic resource of fossils

Human Effect On DesertsAustralia-significant human settlement-extensive sheep and cattle grazing-there has not been a process of desertification (i.e. spread of the desert)-most obvious signs of recent human impacts on Australian deserts have been the extinction of native plants and animals, the invasion of introduced species, and changes in the timing and extent of natural processes such as fire. 

Video Overview 

This is a quick overview of the material we went over in class. 

Click on link below: 

http://player.discoveryeducation.com/index.cfm?guidAssetId=00B679F9-FA21-4696-B72F-4A0E10215261&blnFromSearch=1&productcode=US

Works Citedhttp://www.marietta.edu/~biol/biomes/desert.htmhttp://www.ucmp.berkeley.edu/exhibits/biomes/deserts.phphttp://pubs.usgs.gov/gip/deserts/types/http://www.greenfacts.org/glossary/pqrs/polar-desert.htmhttp://www.marietta.edu/~biol/biomes/images/desert/lichen_9234s.jpg http://library.thinkquest.org/10952/students/2-truc/ALGAE.GIFhttp://library.thinkquest.org/10952/students/2-truc/ALGAE.GIFhttp://ic.galegroup.com/ic/scic/ReferenceDetailsPage/ReferenceDetailsWindow?displayGroupName=Reference&disableHighlighting=false&prodId=SCIC&action=e&windowstate=normal&catId=&documentId=GALE%7CCV2641800004&mode=viewhttp://www.pima.gov/cmo/sdcp/species/fsheets/key/Sag.jpghttp://fc06.deviantart.net/fs13/f/2007/054/9/0/palm_tree_in_Jordan_Desert_by_mayah_stock.jpg http://keep3.sjfc.edu/students/naa07113/e-port/clip_image001.jpg http://www.pestcompany.com/old_pestex/Pest_Control_Atlanta/images/workers_Atlanta_termite_control.gifhttp://online-field-guide.com/Photos/DesertTreeFrog.jpghttp://www.californiaherps.com/snakes/images/ccinctusbaja.jpghttp://gf.state.wy.us/images/04Stamps/05_2nd68owl.jpghttp://fohn.net/camel-pictures-facts/the-pictures/Arabian-Camel.jpghttp://gobidesert.org/content/animals http://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/Uncia_uncia.jpg/220px-Uncia_uncia.jpg http://library.thinkquest.org/C0114235/pic/page27-1.jpg http://upload.wikimedia.org/wikipedia/commons/4/43/07._Camel_Profile,_near_Silverton,_NSW,_07.07.2007.jpg http://www.the-lizard-lounge.com/content/gallery/lizard-pictures/zebra-tailed-lizard/zebra-tailed-lizard-04.jpghttp://www4.uwsp.edu/geo/faculty/ritter/geog101/textbook/climate_systems/tropical_desert.html

"Living in the Environment" Chapter 5 powerpoint and resources"Climate" Science in Context 2008 http://ic.galegroup.com/ic/scic/ReferenceDetailsPage/ReferenceDetailsWindow?displayGroupName=Reference&disableHighlighting=false&prodId=SCIC&action=e&windowstate=normal&catId=&documentId=GALE%7CCX3044900010&mode=view "Desert" Science in Context July 1, 2009http://ic.galegroup.com/ic/scic/ReferenceDetailsPage/ReferenceDetailsWindow?displayGroupName=Reference&disableHighlighting=false&prodId=SCIC&action=e&windowstate=normal&catId=&documentId=GALE%7CCV2641700060&mode=viewPictures:http://www.google.com/imgresq=thermometer&um=1&hl=en&client=safari&sa=N&rls=en&biw=988&bih=651&tbm=isch&tbnid=J8hfnOKsOMWjPM:&imgrefurl=http://photodict.faqs.org/phrase/682/thermometer.html&docid=TTILruGjk8Y1-M&imgurl=http://photohttp://www.google.com/imgres?q=sunshine&start=42&num=10&um=1&hl=en&client=safari&rls=en&biw=988&bih=651&tbm=isch&tbnid=DWmXu8_Retgu2M:&imgrefurl=http://cjandco.wordpress.com/2010/03/17/sunshine/sunshine-2/&docid=Wxn4aPrHT98XaM&imgurl=http://cjandco.files.wordpress.com/2010/03/sunshine.jpg&w=640&h=480&ei=KukTpvEYHb0QGKyPT_BA&zoom=1&iact=rc&dur=219&sig=112289397692582905543&sqi=2&page=4&tbnh=136&tbnw=200&ndsp=12&ved=1t:429,r:9,s:42&tx=150&ty=70http://www.google.com/imgresq=clouds&num=10&um=1&hl=en&client=safari&rls=en&biw=988&bih=651&tbm=isch&tbnid=Uj8m6td-SInqIM:&imgrefurl=http://www.weatherreport.com/Local-weather-forecasts-Cloudhttp://www.google.com/imgresq=water+vapor&start=27&num=10&um=1&hl=en&client=safari&rls=en&biw=988&bih=651&tbm=isch&tbnid=Pua8F9FS4IWyJM:&imgrefurl=http://www.shltrip.com/Yellowstone_NP.html&docid=25sbHqcVjQDrkM&imgurl=http://www.shltrip.com/sitebuilder/images/6s_water_vapor_from_lower_falls_viewed_from_Uncle_Tom_Trail-sharpen-reduced-Yellowstone-2_854-889x673.jpg&w=889&h=673&ei=aqykTqhttp://www.google.com/imgres?q=sunshine&num=10&um=1&hl=en&client=safari&rls=en&biw=988&bih=651&tbm=isch&tbnid=4eg6irYNPfRRmM:&imgrefurl=http://www.wallpaperbase.com/landscape-sunshine.shtml&docid=1ZxJJWQRNkrP4M&imgurl=http://www.wallpaperbase.com/wallpapers/landscape/sunshine/sunshine_6.jpg&w=1024&h=768&ei=kaykTuzEDYHh0QGaurycBQ&zoom=1&iact=rc&dur=290&sig=112289397692582905543&sqi=2&page=1&tbnh=139&tbnw=188&start=0&ndsp=15&ved=1t:429,r:2,s:0&tx=71&ty=30http://www.itsnature.org/category/photos/desert-photos/http://www.google.com/imgresq=cool+desert&start=12&num=10&um=1&hl=en&client=safari&rls=en&biw=988&bih=651&tbm=isch&tbnid=KKwTDAqoWyrEM:&imgrefurl=http://mountaininterval.org/journal/2005/05/&docid=bALqBG0n0EE6YM&imgurl=http://mountaininterval.org/photos/imageshttp://www.google.com/imgresq=raindrop&um=1&hl=en&client=safari&sa=X&rls=en&biw=988&bih=651&tbm=isch&tbnid=8EMFF-J4WHJOXM:&imgrefurl=http://www.downloadsstuff.com/you-love-the-sound-of-the-rain-sign/&docid=b-62RZZindrTEM&imgurl=http://i2.squidoocdn.com/resize/squidoo_images/-Video Biomes: Our Earth's Major Life Zoneshttp://player.discoveryeducation.com/index.cfm?guidAssetId=00B679F9-FA21-4696-B72F-4A0E10215261&blnFromSearch=1&productcode=US

Works Cited 

THE END