Desert Ecosystems Desert an arid region with little

Desert Ecosystems • Desert- an arid region with little or no vegetation • Deserts in North America are located on the western side and run into Mexico. o. Receive little or no water(less than 10 inches per year) o. Are in a rain shadow of the mountains There are 4 main deserts in North America: 1. Great Basin Desert 2. Mojave Desert 3. Sonoran Desert 4. Chihuahuan Desert

1. Great Basin Desert • • • Largest in North America (between Rocky and Sierra Nevada Mountains) Covers most of Nevada and parts of Utah, Oregon, and Idaho A cold desert because it is relatively high in altitude Most precipitation is in the form of snow fall – Not all of it melts into the ground because it evaporates in the spring Plants include: A. Sagebush- a desert bush; does not grow in salty areas B. Salt Bush- a desert bush; does grow in salty area – Plant in the same family such as spinach – Salty because the H₂O evaporates and leaves the salt behind.

• Has playas- lakes that are temporarily dry for most of the year • Deep soil on valley floor because of years of mountain erosion Other Plants and Animals • Plains prickly pear cactus: grows low to ground • Mormon tea • Greasewood • Blackbrush • Snakewood, ect.

Animals- eat grasses and increase amount of sagebush • Mule deer • Pronghorn antelope Ecological Threats • Introduction and spread of alien, invasive species • cheat-grass brome

Mojave Desert • • Covers a wide range of vegetation types. Northern parts are like the Great Basin. The southern parts resemble the Sonoran Desert Contains “Death Valley” – Very hot – 4. 3 cm of rain per year Distinctive Features • Yucca- huge plant that grows to tree like proportions • Cacti- chollas & small cacti – Has to be frost tolerant because of snowfall and ice • 250 types of spring flowers – 80% of these only grow in the Mojave

Sonoran Desert • Different types of soils because of the different types of rocks. • Succulents can survive because there is no frost. • Rain two times per year: – Long rains in winter – Downpours in summer. • Bajadas- slopes where mountain erosion accumulates – Soils are deep and lots of plants grow on them – The loose soil holds an abundance of water • Washes- rivers that carry water down from the mountains – Dry for most of the year yet the soil still remains moist

Chihuahuan Desert • Over Northern Mexico and southern part of USA including west Texas and parts of New Mexico and Arizona • At high altitude (1, 000 -1, 500 m) • Summers are hot winter are relatively cool with night frost • Rainfall is relatively high (20 -30 cm) – almost all in summer • Nearly 80% has calcium rich soils because of lime stone – Indicates it was once under the ocean – Has small cacti and frost tolerate grasses • Major Vegetation • Low Areas – Creosote bush/ Tar bush • Upper areas – Bajadas – Yucca (Spanish daggers – sharp leaves) • High Areas – More bushes and small trees – H 2 O is more abundant in the valley floor

Highest • True trees – Pines, oaks, junipers • Microbes – Lichens, Fungi, Cyanobacteria General Desert Information • Deserere comes from the word deserere( Latin for abandoned) • A desert will form if the rate of precipitation is less than the rate of evaporation • Not all deserts are hot, there are some in the polar regions • Largest desert is the Sahara – Size of the US and stretches across north Africa • • Most of central Australia is desert Southern Africa has the Namib and Kalahari desert and Kalahari Bushmen Most desert are not sandy ( rocks , pebbles , and gravel) Dust Devils- Warm air rises quickly in an area and as it leaves, the other air rushes in to fill the space and carries sand with it.

Animals of the Desert • Snakes • Rattlesnakes • Mojave rattlesnake • Lives in the Mojave Desert • Length 2 -4 ft • Is considered one of the most venomous snakes in the U. S. • Venom is neurotoxin • Western Diamondback Rattlesnake • Range is Central/West Texas to Southern New Mexico/California • Length 3 -5 ft but some can get as long as 7 • Venom is hemotoxin

Animals Cont. • Lizards – Gila Monster • Range is the southwest US and Mexico • Venom is a neurotoxin – Venomous spit • Length – Up to 2 ft. • Arachnids – Scorpion • Venom is a neurotoxin • Various species throughout the US – Tarantula • Widespread through out the southwest US • Can get 3 -4 inches in size • Can live 10 to 12 years

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