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
• slide4 picture
• slide 5 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