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Desert: The Biome of Extremes

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

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  1. Desert:The 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. 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?

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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

  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 Plants Animals

  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 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

  17. 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

  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 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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