Tundra
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
