Transcript Polar deserts - Tartu Veeriku Kool

World Biomes
Polar desert
(Polar barren)
Introduction
• Polar deserts on the Earth cover nearly 5 million
square kilometers and are mostly bedrock or gravel
plains. Sand dunes are not prominent features in
these deserts, but snow dunes occur commonly in
areas where precipitation is locally more abundant.
Climate
• Polar deserts are areas with annual precipitation less
than 250 millimeters and a mean temperature during
the warmest month of less than 10° C.
• In the winter, temperatures can be as low as -30 - -60°
C
• Also the winds have an enormous effect on the
weather. They bring dramatic storms with visibility
reduced to less than 100 feet.
• The year is divided about equally between day
(summer) and night (winter) owing to the continuous
position of the Sun above or below the horizon during
these seasons.
Distribution of biome
• At the North Pole is the Arctic Ocean, lying in the midst
of islands and landmasses (the northernmost being
Greenland) and the Canadian arctic archipelago. In all
lowland areas the extreme cold is relieved with abovefreezing temperatures for a month or more each year,
allowing for a varied plant and animal life.
• The South Pole is occupied by the continent of
Antarctica, the mountains of which project through the
world's greatest ice cap. No more than about 4 percent
of the Antarctic's land is capable of sustaining life,
while only the coast of Graham Land on the Antarctic
Peninsula and several off-lying islands are warmed
each year by above-freezing temperatures.
Soil
• Considerable
cover of a soil
crust, which
develops in sites
exposed to
continued surface
runoff from melting
snow for some of
the short growing
season.
Plants
• Plants cover less than five percent of this ecoregion
because of the very cold temperatures, short growing
season, and dry soil. Heath, mosses, and lichens are
hardy enough to survive in the harsh climate, and
flowering plants such as the Arctic poppy have
blossoms that track the sun during the day,
concentrating the sun’s heat on themselves.
Arctic Poppy
Plants in Antarctica
Animals
• All the wildlife is connected with sea, because there is
very little food on land.
• Vast colonies of seabirds can be found nesting on the
cliffs of this ecoregion.
• Not many animals spend all year there.
Harp seal
Walrus
Polar bear
Atlantic Puffin
Seabird colony
Beluga
Narwhal
Adelie penguin
Emperor penguin
Antarctic Petrel
Southern Fulmar
Leopard seal
Southern elephant seal
Blue whale
Killer whale
People I
• Few direct threats exist for this ecoregion, simply
because humans are largely absent. But where
humans have tread, this ecoregion has suffered. Plans
for a northern shipping route through the Russian
Arctic could open up oil, gas, and other natural
resources for exploitation. This could increase the risk
of oil spills and introduce species such as rats to the
ecoregion, which could have drastic consequences for
nesting seabirds.
• The Novaya Zemlya area has a unique problem. It has
been serving as a test area for nuclear weapons and
suffers from elevated levels of plutonium, cesium, and
other radioactive pollutants.
People II
• Global climate change could upset the balance of life
in the ecoregion by melting ice, raising temperatures,
and upsetting the food chain.
• Ozone depletion threatens to leave the Antarctic open
to dangerous amounts of the sun’s ultraviolet
radiation. And pollution both from scientific expeditions
and a growing tourism industry could also become
threats if not well managed.