Chapter 7 Desert and Tundra

DESERTS RECEIVE LITTLE RAIN – cm per year RECEIVE LITTLE RAIN – cm per year SOIL IS RICH IN MINERALS – but poor in organic material (nutrients) because there is NO LEACHING – rain that carries minerals deeper into the soil SOIL IS RICH IN MINERALS – but poor in organic material (nutrients) because there is NO LEACHING – rain that carries minerals deeper into the soil SOIL is loose and dry and blows away easily in the wind SOIL is loose and dry and blows away easily in the wind PAVEMENT – hard desert floor is exposed (hard-baked sand and rock) PAVEMENT – hard desert floor is exposed (hard-baked sand and rock)

DESERT TYPES TWO TYPES IN NORTH AMERICA COOL DESERTS –to the east of mountain ranges in the north western U.S. Ex: Sierra Nevada, Rocky Mountains HOT DESERTS – in the southern U.S. (Ex: Arizona, New Mexico, western Texas, Mexico) Anza-Borrego Desert State Park, Texas Badlands National Park, South Dakota

DESERT CLIMATE Very Low Rainfall – cm in any single year Very Low Rainfall – cm in any single year Most deserts receive less than 10 cm Most deserts receive less than 10 cm Few short thunderstorms with long dry periods Few short thunderstorms with long dry periods Temperature Variation – great variation due to lack of moisture in the air Ex: freezing cold at night and searing hot during the day Temperature Variation – great variation due to lack of moisture in the air Ex: freezing cold at night and searing hot during the day

DESERT PLANTS Must be able to Absorb and Hold Water in thick spongy tissues (Ex: Cacti or Aloe vera which are succulents) Adapt to Prevent Water Loss (spines on cactus are modified leaves) Have broad shallow roots (cacti) or very deep tap roots (mesquite and Joshua tree)

DESERT ANIMALS Many types of animals: insects reptiles, birds and mammals. Many types of animals: insects reptiles, birds and mammals. Insects and reptiles have thick outer shells (scorpion, tarantula) or scales (gila monster) to protect them from the harsh climate and retain water Insects and reptiles have thick outer shells (scorpion, tarantula) or scales (gila monster) to protect them from the harsh climate and retain water Mammals either stay underground during the day (kangaroo rat) or have adaptations like the long ears of the fennec which help to release heat from their bodies Mammals either stay underground during the day (kangaroo rat) or have adaptations like the long ears of the fennec which help to release heat from their bodies

DESERT FORMATION Deserts are on every continent except Antarctica Desert belts form on either side of the equator Sun rays heat the air at the equator causing rapid evaporation followed by repeated rainfall The dry air that’s left after the rain moves towards the poles This causes deserts to form

DESERT FORMATION RAINSHADOW EFFECT – In the U.S. winds move from the west coast toward the east coast In the U.S. winds move from the west coast toward the east coast Moist air from the Pacific passes over the Sierra Nevada mountains - the cold air forces the water out and leaves cool dry air to continue towards the east. Moist air from the Pacific passes over the Sierra Nevada mountains - the cold air forces the water out and leaves cool dry air to continue towards the east. The cool dry air takes any moisture from the soil east of the mountains and causes deserts to form The cool dry air takes any moisture from the soil east of the mountains and causes deserts to form

DESERTIFICATION Regions near deserts that are not as dry are called SEMIARID (partially dry). HUMAN ACIVITY such as overgrazing, deforestation, bad farming practices all cause vegetation loss. Climate change and drought also cause desertification. Lack of vegetation causes soil erosion, leaving hard packed dirt and rocks exposed. This changes weather patterns, heats the air and land and starts desert formation. Spreading deserts are found in Africa, China, Europe (Spain), South America, the Caribbean and the U.S. Results in between 6 and 12 million square kilometers of soil loss.

TUNDRA COLD, WINDY DRY REGION COLD, WINDY DRY REGION LOCATED JUST BELOW THE NORTH POLE LOCATED JUST BELOW THE NORTH POLE ALASKA, CANADA, GREENLAND, ICELAND, NORWAY, SIBERIA, ASIA ALASKA, CANADA, GREENLAND, ICELAND, NORWAY, SIBERIA, ASIA LARGEST BIOME IN AREA – 10% OF THE EARTH’S SURFACE LARGEST BIOME IN AREA – 10% OF THE EARTH’S SURFACE LIMITED BIODIVERSITY – FRAGILE AND UNSTABLE ECOSYSTEM LIMITED BIODIVERSITY – FRAGILE AND UNSTABLE ECOSYSTEM

TUNDRA FACTS Less than 25 cm precipitation (mostly snow and ice) per year Air temperature rarely rises above 10 o C (50 o F) which is the limiting factor for this biome PERMAFROST – only the top layer (~ 8 cm) of soil ever defrosts - the rest stays frozen Rainfall can’t soak into the ground forms marshes and bogs instead Plants stay low to the ground and do not recover quickly

TUNDRA PLANTS Short growing season (60 days) Short growing season (60 days) Mosses, lichens, low shrubs and grasses – few trees (willows and birch) are very small Mosses, lichens, low shrubs and grasses – few trees (willows and birch) are very small Roots are shallow, because of PERMAFROST Roots are shallow, because of PERMAFROST Have to be able to survive long cold winters with no light for 6 months Have to be able to survive long cold winters with no light for 6 months

TUNDRA ANIMALS Many tundra animals migrate (long-distance seasonal travel) with the weather and the food sources like migrating birds. Arctic hare, lemmings, ground squirrel, caribou, musk oxen, puffin, snow goose, arctic loon Few predators: Arctic fox, polar bears, snowy owl, wolverines, wolves,

CHAPTER 7 VOCABULARY LEACHING LEACHING PAVEMENT PAVEMENT SUCCULENT SUCCULENT NOCTURNAL NOCTURNAL RAINSHADOW EFFECT RAINSHADOW EFFECT DESERTIFICATION DESERTIFICATION PREMAFROST PREMAFROST MIGRATION MIGRATION CLIMATOGRAM CLIMATOGRAM