Desert Ecosystem

What do all deserts have in common?

1. barely any rain

2. soils are rich in minerals/poor in organic material

Why are desert soils rich in minerals and poor in organic materials?

rain carries minerals deeper into soil, but there's little rain in the desert. Lack of rain slows decay of organic material

Leaching

when rain carries minerals deeper into soil

Pavement

when wind blows away loose dry land and exposes the desert floor -- a hard-baked sand or bare rock

Desert types in the US

1. cool deserts

2. hot deserts

Cool deserts

elevation, latitude, east side of Sierra Nevada, and rocky mountains

Hot deserts

south west- Arizona, New Mexico, and West Texas

Desert climate

*rarely more than 25 cm (most get less than 10 cm during short thunderstorms, followed by long, dry seasons)

*water runs off instead of being absorbed

*lack of rain equal hot days/cool nights

Limiting Factor

Rainfall since, it determines what plants can grow and what animals can live there

Desert Organism Survival Challenges

1. lack of water

2. extreme temperatures

Desert Organism Survival Techniques

1. physical adaptations

2. behavioral adaptations

Desert Plants

(Cacti and Aloe)

*absorb water and prevent loss

*store water in tissue (succulents)

*roots; shallow over wide area with some deep roots

Desert Animals

*insects, reptiles, birds, mammals

*get water from what they eat

*prevent water loss and survive heat

Desert Animal Survival Techniques

* physical: outer shells and scares (insects/reptiles)

* behavioral: desert rodents are nocturnal (spend days in underground burrow and forage at night)

nocturnal

* active at night (hunt, forage, eat)

* sleep during day

desert geography

* deserts cover 30% of land and are on every continent except Antarctica

* Tropic of Cancer (northern belt, 23° North)

* Tropic of Capricorn (southern belt, 23° South)

desertification

the transformation of a semiarid land to a desert as a result of human activity

Categories of deserts

* tropical: southern Sahara (Africa)

* temperate: Mojave (southern California)

* cold: Gobi (China)

Tropical Deserts

* Southern Sahara (Africa)

* temperatures high year-round

* little rain (2 months)

* driest place on earth (no plants)

Temperate Deserts

* Mojave (Southern California)

* temperatures high in summer, low in winter

* more precipitation than tropical

* plants = succulents and shrubs

Cold Deserts

* Gobi (China)

* summers are warm to hot

* winters are cold

Semidesert

area between desert and grassland

* thorny trees and shrubs

* long periods of no rain followed by brief, heavy rains

Rain shadow effect

An area having relatively little precipitation due to the effect of a topographic barrier, especially a mountain range, that causes the prevailing winds to lose their moisture on the windward side, causing the leeward side to be dry.