Dead organic material functions as a nutrient pool. The two major
nutrients are nitrogen and phosphorus. Nitrogen is created by biological
fixation, and phosphorus is created by precipitation. Tundra is separated
into two types: arctic tundra and alpine
tundra.
Characteristics of Tundra
1. Extremely cold climate
2. Low biotic diversity
3. Simple vegetation structure
4. Limitation of drainage
5. Short season of growth and reproduction
6. Energy and nutrients in the form of dead organic
material
7. Large population oscillations
Arctic
Arctic tundra is located in the northern hemisphere, encircling the
North Pole and extending south to the coniferous forests of the taiga.
The arctic is known for its cold, desert-like conditions. The growing
season ranges from 50 to 60 days. The average winter temperature is
-34° C (-30° F), but the average summer temperature is 3-12°
C (37-54° F), which enables this biome to sustain life. Rainfall
may vary in different regions of the arctic. Yearly precipitation,
including melting snow, is 15 to 25 cm (6 to 10 inches). Soil is formed
slowly. A layer of permanently frozen subsoil called permafrost exists,
consisting mostly of gravel and finer material. When water saturates
the upper surface, bogs and ponds may form, providing moisture for
plants. There are no deep root systems in the vegetation of the arctic
tundra; however, there are still a wide variety of plants that are
able to resist the cold climate. There are about 1,700 kinds of plants
in the arctic and sub arctic, and these include:
Low
shrubs, sedges, reindeer mosses, liverworts, and grasses
400
varieties of flowers
crustose
and foliose lichen
All of the plants are adapted to sweeping winds and disturbances
of the soil. Plants are short and group together to resist the cold
temperatures and are protected by the snow during the winter. They
can carry out photosynthesis at low temperatures and low light intensities.
The growing seasons are short and most plants reproduce by budding
and division rather than sexually by flowering. The fauna in the arctic
is also diverse:
Herbivorous
mammals: lemmings, voles, caribou, arctic hares and squirrels
Carnivorous
mammals: arctic foxes, wolves, and polar bears
Migratory
birds: ravens, snow buntings, falcons, loons, ravens, sandpipers,
terns, snow birds, and various species of gulls
Insects:
mosquitoes, flies, moths, grasshoppers, black flies and arctic bumble
bees
Fish:
cod, flatfish, salmon, and trout.
Animals are adapted to handle long, cold winters and to breed and
raise young quickly in the summer. Animals such as mammals and birds
also have additional insulation from fat. Many animals hibernate during
the winter because food is not abundant. Another alternative is to
migrate south in the winter, like birds do. Reptiles and amphibians
are few or absent because of the extremely cold temperatures. Because
of constant immigration and emigration, the population continually
oscillates.
Alpine
Alpine tundra is located on mountains throughout the world at high
altitude where trees cannot grow. The growing season is approximately
180 days. The night time temperature is usually below freezing. Unlike
the arctic tundra, the soil in the alpine is well drained. The plants
are very similar to those of the arctic ones and include:
Mammals:
picas, marmots, mountain goats, sheep, elk
Birds:
grouse like birds
Insects:
springtail's, beetles, grasshoppers, butterflies.
