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Desert: The Biome of Extremes. By: Lucas, Melissa, Trevor, Alicia, and David. From our presentation you will learn:. What makes a desert a desert Where deserts are found. Climatic and geographic factors that cause deserts and determine location Life in deserts and mechanisms for survival

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desert the biome of extremes

Desert:The Biome of Extremes

By:

Lucas, Melissa, Trevor,

Alicia, and David

slide2

From our presentation you will learn:

  • What makes a desert a desert
  • Where deserts are found
  • Climatic and geographic factors that cause deserts and determine location
  • Life in deserts and mechanisms for survival
  • Citations for references
what is a desert
What is a Desert?

“A desert is a region with mean annual precipitation of less than 10 inches, with potential to evaporate more water than falls as precipitation, and so little vegetation that it cannot support abundant life.”

– Professors Jean Bahr and Chuck DeMets

University of Wisconsin-Madison

where are deserts found
Where are deserts found?
  • United States
  • Mexico
  • South America
  • Africa
  • South Central Asia
  • Australia
  • Antarctica
  • NOT EUROPE
what causes deserts
Deserts are classified by location and weather patterns. There are several overlapping classification systems. To keep it simple here is one system with four classes of desert:
  • Coastal Deserts
  • Subtropical Deserts
  • Polar Deserts
  • Mid-Latitude Deserts
What Causes Deserts?
subtropical deserts
Two 5o strips at 30o north and 30o south latitudes (see map)

Air currents heat up as they move toward the equator, causing “trade winds”

Dry winds drive away clouds, more sunlight heats the land

Subtropical Deserts
subtropical deserts cont
Air masses hold a great amount of water vapor, “wicking” moisture away from land underneath

Most major hot deserts are subtropical deserts

Example: Sahara Desert

world’s largest hot desert - 3.5 million square miles

temperatures can reach 57° C (135° F)

Subtropical Deserts, cont.
cool coastal deserts
Found along the coastline at same latitudes as subtropical deserts

Average temperature much cooler due to cold offshore ocean currents

Example: Atacama Desert of Chile

All moisture in form of fog

No rain for 40 or 400 years (depending on source)

Cool Coastal Deserts
polar deserts
Cover nearly 20 million square miles

Mostly bedrock or gravel

Caused by location on planet

Low-angle sunlight causes cold conditions

Cold air carries little moisture

Example: McMurdo Dry Valleys of Antarctica

Polar Deserts
mid latitude deserts
Found in continental interiors, between 30°-50° N. and S.

Caused by either land barriers or distance from oceans (continentality)

Very hot summers, very cold winters

Example: Gobi Desert of Mongolia

Mid-Latitude Deserts
other deserts
Other Deserts
  • Paleodeserts:ancient deserts in areas no longer dry

Example: Nebraska Sand Hills

  • Extraterrestrial deserts: deserts on other planets

Example: Martian “Sand Seas”

challenges of desert life
Challenges of Desert Life
  • Temperature extremes
  • Lack of water
  • Scarce food
life in the hot desert
Life in the ~Hot~ Desert

Physical

Adaptation

Behavior

Plants

Animals

animal adaptation
Animal Adaptation

Behavior

  • Estivation – summer hibernation
  • Nocturnal feeding
  • Daytime rest – dens, holes, shade
  • Energy conservation
  • Physical
  • Careful kidneys
  • Salt glands (no sweat glands)
  • Skin structures
  • Light coloration
  • Life cycle regulation
plant adaptation
Plant Adaptation

Cactus (Americas) and euphorbia (Africa)

  • Shallow root systems - stability and moisture
  • No leaves, green trunk can photosynthesize
  • Can store a lot of water (saguaro 2,000 lbs!)

Other Plants

  • Far-reaching root systems, horizontal or vertical
  • Compact growth
  • Leaves small, absent, or ephemeral (ex: ocotillo)
  • Thick cuticle (waxy layer) or “fur” on leaves
interesting information
Interesting Information
  • 40 different species of rodents found in the Sahara Desert
  • 1/3 of Earth’s land surface covered by deserts
  • 1200 different species of insects found in Sahara Desert
  • Hottest recorded temperature: 134ºF. Death Valley, USA
  • Camels drink water up to 25% of their body weight
  • Largest desert plant: saguaro of N. America
works cited
Works Cited
  • Utah Education Network: www.uen.org/
  • Temperature converter: www.geocities.com/tempconverter/
  • State of Utah Resources Web: www.surweb.org/
  • Types of deserts USGS: pubs.usgs.gov/gip/deserts/types/
  • Earth Science Explorer (in cooperation with NASA) www.cotf.edu/ete/modules/msese/earthsys.html
works cited cont
Works Cited, cont.
  • U.Minnesota Geography 106 lecture notes www.geology.wisc.edu/~chuck/G1062000/Lecture_links/demets_l5.html
  • The Learning Network: www.infoplease.com
  • Köppen Climate Classificationwww.hqlist.demon.nl/gvg/ctkoppe2.htm
  • The World\'s Biomes, UC Berkeley: www.ucmp.berkeley.edu/glossary/gloss5/biome/deserts.html
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