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Desert: The Biome of Extremes

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'A desert is a region with mean annual precipitation of less than 10 inches, with ... 40 different species of rodents found in the Sahara Desert ... – PowerPoint PPT presentation

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Title: Desert: The Biome of Extremes


1
DesertThe Biome of Extremes
  • By
  • Lucas, Melissa, Trevor,
  • Alicia, and David

2
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

3
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
4
Where are deserts found?
  • United States
  • Mexico
  • South America
  • Africa
  • South Central Asia
  • Australia
  • Antarctica
  • NOT EUROPE

5
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

6
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

7
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
  • worlds largest hot desert - 3.5 million square
    miles
  • temperatures can reach 57 C (135 F)

8
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)

9
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

10
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

11
Other Deserts
  • Paleodeserts ancient deserts in areas no longer
    dry
  • Example Nebraska Sand Hills
  • Extraterrestrial deserts deserts on other
    planets
  • Example Martian Sand Seas

12
Challenges of Desert Life
  • Temperature extremes
  • Lack of water
  • Scarce food

13
Life in the Hot Desert
Physical Adaptation
Behavior
Animals
Plants
14
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

15
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

16
Interesting Information
  • 40 different species of rodents found in the
    Sahara Desert
  • 1/3 of Earths 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

17
Works Cited
  • Utah Education Network www.uen.org/
  • Temperature converter www.geocities.com/tempconve
    rter/
  • State of Utah Resources Web www.surweb.org/
  • Types of deserts USGS pubs.usgs.gov/gip/deserts/t
    ypes/
  • Earth Science Explorer (in cooperation with NASA)
    www.cotf.edu/ete/modules/msese/earthsys.html

18
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 Classification www.hqlist.demon.nl/
    gvg/ctkoppe2.htm
  • The World's Biomes, UC Berkeley
    www.ucmp.berkeley.edu/glossary/gloss5/biome/desert
    s.html
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