The Desert Biomes tropical and polar By: Emily Griffin

Deserts in general A desert is an area where: evaporation exceeds precipitation Sparse widely spaced mostly low vegetation Cover 30% of lands surface Can be tropical, temperate, or polar

Tropical deserts location

Examples Sahara in North Africa Thar in India/Pakistan Namib Desert

Tropical deserts precipitation Dry with very little rain On average under 1” per year  formed by high pressure zones with warm descending air currents but moisture evaporates before becoming rain

Tropical deserts temperature Generally clear skies allow the sun’s rays to directly beat on the soil making it very hot Clear skies also account for cool nights, because there is very little stored heat in sand deserts are also very dry and hot because the “soil” absorbs very little moisture Sahara Desert Temperatures

Tropical deserts Soil Desert soil is low in organic matter and lack the darker soil horizons, they are unable to support much life due to the low precipitation, but are otherwise nutrient rich. Life that the soil can support is sparse and limited to  ground-hugging shrubs, and short woody trees.

Biotic adaptation of plants in tropical desert Cactus Instead of producing leaves, desert cacti produce stems and a spine capable of holding and storing enough water to survive Some cactus have waxy leaves to keep water in Larger cacti need either long or spread out root systems like the saguaro cactus

Biotic adaptation of animals in tropical deserts

Biotic adaptation of animals in tropical deserts Thorny Devil drinks water with its skin “the way the scales on the body are structured, it collects dew and channels it down to the corners of the mouth, where the lizard drinks it. You can actually watch the lizard’s skin darken as it soaks up whatever liquid remains from even the muckiest of puddles” (Zookeeper Rick Schwartz).

Biotic adaptations of animals in the tropical desert Fennec fox of North Africa has big ears, loaded with blood vessels, allowing the animals to dissipate excess body heat, and thick fur to retain heat during the cold nights.

Human effects on tropical desert biome Desertification through over farming, deforestation, and overgrazing leads to the creation of more deserts Higher temperatures may produce an increasing number of wildfires that change desert landscapes by eliminating slow-growing trees and shrubs and replacing them with fast-growing grasses Lots of oil is in deserts and oil drilling and mining damages deserts that take a long time to re-build Nuclear waste is often dumped in deserts causing wasteland and killing species Deserts have been used as nuclear testing grounds causing disruption in the environment even though people don’t live there

Polar desert The yellow areas are the cold deserts in the world.

Cold desert precipitation and temperature the average yearly precipitation ranges from 15-26 cm annual precipitation has reached a maximum of 46 cm and a minimum of 9 cm the average winter temperature is between -2 to 4° C the average summer temperature is between 21-26° C The Gobi Desert

Soil in the cold desert biomes The soil is: heavy silty salty relatively porous and drainage is good so that most of the salt has been leached out

Cold desert plant adaptations The cold climate and salty soil lead to little plant growth Three common plants are: Grasses shadscale Lichen

Cold desert animals Emperor penguins, Skua, and Kangaroo rats are all animals that live in the cold desert biome. They all have adaptation like thick fur or feathers. Also, the Kangaroo rat produces many offspring to better increase its chances of survival as a species.

Human effects on cold deserts A major problem in cold deserts is desertification Desertification is caused by: Overusing groundwater Overgrazing Few humans live there, but ozone depletion and the greenhouse effect cause the colder deserts to warm up

Sources polar desert picture 1 slide 2 picture slide 3 picture http://www.ucmp.berkeley.edu/exhibits/biomes/deserts.php http://environment.nationalgeographic.com/environment/habitats/desert-threats http://wildtracks.wordpress.com/world-ecosystems/desert-ecosystems/cold-desert-ecosystem/ http://www.eoearth.org/view/article/151704/ http://www.blueplanetbiomes.org/desert.htm graph 2