Anaktuvuk Pass, Alaska |
Did you know that
the Arctic Tundra is the world's youngest biome? It was
formed 10,000 years ago. Located at latitudes 55° to
70° North, the tundra is a vast and treeless land which
covers about 20% of the Earth's surface, circumnavigating
the North pole. It is usually very cold, and the land is
pretty stark. Almost all tundras are located in the Northern
Hemisphere. Small tundra-like areas do exist in Antarctica
in the Southern Hemisphere, but because it is much colder
than the Arctic, the ground is always covered with snow and
ice. Conditions are not right for a true tundra to form.
Average annual temperatures are -70°F
(-56°C). Tundra comes from
the Finnish word "tunturia", which means a barren land. The
ground is permanently frozen 10 inches to 3 feet (25 to 100
cm) down so that trees can't grow there. The bare and
sometimes rocky ground can only support low growing plants
like mosses, heaths, and lichen. In the winter it is cold
and dark and in the summer, when the snow and the top layer
of permafrost melt, it is very soggy and the tundra is
covered with marshes, lakes, bogs and streams that breed
thousands of insects and attract many migrating
birds. The main seasons are
winter and summer. Spring and fall are only short periods
between winter and summer. The tundra is the world's coldest
and driest biomes. The average annual temperature is
-18° F (-28° C). Nights can last for weeks when
the sun barely rises during some months in the winter, and
the temperature can drop to -94° F (-70° C).
During the summer the sun shines almost 24 hours a day,
which is why the Arctic is also called the Land of the
Midnight Sun. Summer are usually warm. Temperatures can get
up to 54° F (12° C), but it can get as cold as
37° F (3° C). Average summer temperatures range
from 37° to 60°F (3° to 16°C).
The Arctic tundra is
also a windy place and winds can blow between 30 to 60 miles
(48 to 97 kilometers) per hour. Of the North American,
Scandinavian and Russian tundras, the Scandinavian tundra is
the warmest, with winter temperatures averaging 18°F
(-8°C) The tundra is
basically like a desert when it comes to precipitation. Only
about 6 - 10 inches of precipitation (mostly snow) fall each
year. Below the soil is the tundra's permafrost, a
permanently frozen layer of earth. During the short summers
the top layer of soil may thaw just long enough to let
plants grow and reproduce. Since it can't sink into the
ground, water from melting permafrost and snow forms lakes
and marshes each summer. There is barely any
vegetation in the tundra, only about 1,700 different
species, which isn't very much. These are mostly shrubs,
sedges, mosses, lichens and grasses. There are about 400
varieties of flowers. The growing season is only about 50 to
60 days long. There are no trees, except for some birches in
the lower latitudes. The ground is always frozen beneath the
top layer of soil, so trees can't send their roots down.
Willows
do grow on some parts of the tundra but only as low carpets
about 3 inches (8 cm) high. Most plants grow in a dense mat
of roots which has developed over thousands of years. The
soil is very low in nutrients and minerals, except where
animal droppings fertilize the soil. Surprisingly there
are animals in the tundra. Although there isn't a lot of
biodiversity, only 48 species of land mammals are found on
the tundra, there are a lot of each species. These consist
of slightly modified shrews, hares, rodents, wolves, foxes,
bears and deer. There are huge herds of caribou
in North America (known as reindeer in Eurasia) which feed
on lichens and plants. There are also smaller herds of
musk-oxen.
Wolves, wolverines,
arctic foxes, and polar
bears are
the predators of the tundra. Smaller mammals are
snowshoe
rabbits and
lemmings. There aren't many different species of insects in
the tundra, but black flies, deer flies, mosquitoes and
"no-see-ums" (tiny biting midges) can make the tundra a
miserable place to be in the summer. Mosquitoes can keep
themselves from freezing by replacing the water in their
bodies with a chemical called glycerol. It works like an
antifreeze and allows them to survive under the snow during
the winter. The marshy tundra is a great place for migratory
birds like the harlequin
duck,
sandpipers and plovers. The tundra is one of
Earth's three major carbon dioxide sinks. A carbon dioxide
sink is a biomass
which takes in more carbon dioxide than it releases. Carbon
dioxide is a greenhouse gas that contributes to global
warming. During the short summer tundra's plants take in
carbon dioxide, sunlight and water in the process of
photosynthesis. Plants normally give off carbon dioxide
after they die and decompose. But because of the short, cool
summer and freezing winter temperatures, plants can't
decompose. Remains of plants thousands of years old have
been found in the tundra permafrost. In this way the tundra
traps the carbon dioxide and removes it from the atmosphere.
Today global warming is melting the permafrost of the tundra
and every year several feet of tundra are lost. As the
tundra melts, the plant mass decomposes and returns carbon
dioxide to the atmosphere. The tundra is a very
fragile environment. The extremely cold temperatures makes
it a difficult environment to survive in during the winter,
and plants and animals have a hard time coping with any
extra stresses and disturbances. More people moving to the
tundra to work in the mines and oil rigs have created towns
and more roads. Some animal's movements to traditional
feeding and denning grounds have been disrupted by these
obstacles. When they try to pass through a town they are
often scared away or shot. With their feeding patterns
disrupted, many polar bears have starved. The Alaskan oil
pipeline was built across a caribou migration route. In some
places the pipeline has been raised above the ground so the
caribou can pass under it. Pesticides have been used to
control the hordes of insects. Thousands of migrating birds
come to the tundra because of the abundant insects. Through
the food chain the pesticides reach many of the animals that
live on the tundra. Pollution from
mining and drilling for oil has polluted the air, lakes and
rivers. The land around some nickel mines in Russia has
become so polluted that the plants in the surrounding area
have died. Footprints and tire tracks can be visible for
many years after they were made. When the sun hits the ruts
it causes the permafrost to melt. This causes erosion and
the ruts get bigger, and eventually the ruts turn into
gullies. Tracks made during WW II have grown so large that
some of them are now lakes. The tundra is not a
cold and useless wasteland. It is a very fragile environment
and the plants and animals that have made their home on the
tundra biome have made some incredible adaptations to the
long, cold winters and the short but abundant summers. They
live on a precarious edge and the smallest stresses can
bring about their destruction. by Whitney S.
2002
bibliography: Kaplan, E. (1996).
Biomes of the World: Tundra. Hong Kong: Marshall
Cavendish Corporation. "Encyclopedia.com -
Results for tundra",
http://www.encyclopedia.com/articles/13116.html, (June
2000) "The World's Biomes:
Tundra",
http://www.latymer-upper.org/geog/sixth/tundra%20the%20not%20do%20barren%20land.htm,
(July 2000). Photo Credit:
"Interface", http://www.nsbsd.k12.ak.us/PROJECTS/arctic_year/anaktuvuk/interface.htm,
(July 2000).
*Check out this website for great info on life on the tundra
and the people who live there!
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