Where is the Tundra Located?
The tundra is located at the top of the world, near the North Pole. This enormous biome, extremely uniform in appearance, covers a fifth of the earth's surface.
The most distinctive characteristic of tundra soil is its permafrost, a permanently frozen layer of ground. During the brief summers, the top section of the soil may thaw out allowing plants and microorganisms to grow and reproduce. However, these plants and microorganisms become dormant during the cold winter months.
There is another region called alpine tundra, which is found on the tops of tall, cold mountains. The word tundra derives from the Finnish word for barren or treeless land. The tundra is the simplest biome in terms of species composition and food chains. * low precipitation (less than five inches/year) coupled with strong, drying winds. Snowfall is actually advantageous to plant and animal life as it provides an insulating layer on the ground surface.
Soil: No true soil is developed in this biome due to the edaphic factors mentioned above.
Fauna: Strategies evolved to withstand the harsh conditions of the tundra can be divided among those species that are resident and those that are migratory.
* Among the small number of bird (e.g., ptarmigan) and mammal (e.g., muskox, arctic hare, arctic fox, musk ox) species that reside year-round on the tundra one commonly finds: Morphological adaptations
* large, compact bodies following Bergmann's and Allen's rules * a thick insulating cover of feathers or fur * pelage and plumage that turns white in winter, brown in summer Physiological adaptations
* ability to accumulate thick deposits of fat during the short growing season. Fat acts as insulation and as a store of energy for use during the winter, when animal species remain active. Population adaptations
* cyclical fluctuations in population size, best seen perhaps in the lemming, a small rodent which is the major herbivore in the tundra's simple food chain. Predator populations and plant populations respond in kind to the peaks and crashes of the herbivore populations.
* Migratory species such as waterfowl, shorebirds and caribou adapt to the tundra by avoiding the most severe conditions of winter. Each year at the end of the short growing season they move southward into the boreal forest or beyond, but return to the tundra to breed.
Aperiodic emigration from the tundra is exhibited by the snowy owl during those years that the lemming populations have crashed. Those winters see snowy owl irruptions as far south as Virginia. Most owls are found with empty stomachs and do not survive to return to the Arctic.
Distribution: The tundra biome is restricted to the high latitudes of the northern hemisphere in a belt around the Arctic Ocean. Many of its species, both plant and animal, have circumpolar distribution areas.
Within the tundra biome a latitudinal zonation of communities is realized:
* High Arctic Tundra: essentially confined to the islands of the Arctic Ocean and characterized by scattered lichens and mosses on care rock surfaces and perennial forbs growing in protected crannies among sharp, ice-fractured rock debris.
* Middle Arctic Tundra: restricted to the Arctic Coastal plain where level terrain, a thin active layer, and freeze and thaw result in or rock polygons. The sorting of particles by freeze-thaw activity results in a waterlogged center to the polygons, a microhabitat conducive to sphagnum moss and sedges; and an outer ring that is drier and provides a microhabitat favorable to forbs and some dwarf heaths.
* Low Arctic Tundra: the majority of the tundra lies on better drained slopes with greater depth to permafrost than is encountered on the Arctic coastal plain. Here there is a greater frequency of woody shrubs: willow, birch, and various berry-bearing members of the heath family. Along streams willows and alders may be 10 feet high. On south-facing slopes needleleaf evergreen trees (spruce and fir) are established and represent the northernmost extensions of the great boreal forest to the south. (Such areas where two biomes interdigitate are known as.)
Many tundra species can be found at high elevations in the mountains of the northern hemisphere. The of high elevations experiences a different climate--in terms of day length and seasons--than does the true tundra of the Arctic. However, thin soils and cold temperatures create an environment that many middle latitude trees cannot tolerate and thus allow tundra species to invade and thrive.
In the tropics, the climate of very high elevations is extremely different than that of the Arctic. Freeze-thaw, instead of following a seasonal cycle, follows a diurnal cycle. Also, the peaks are isolated from the Arctic tundra. Often endemic species derived from a tropical flora or from Antarctic flora create the unique communities of tropical high mountain tops.
These areas are also some of the driest in the world. They include: the Arctic and Antarctic regions the Tundra regions.
All available moisture at the North and South Poles (i.e. Arctic and Antarctic) is in ice form. The air at the poles is descending so no condensation can take place. The prevailing winds blowing in these areas are continental in origin and are not bringing moisture onto the land. The winds originate at the poles and are thus icy cold, freezing all available moisture.
In the case of the Tundra regions of Canada, the available moisture forms as snow because of the very cold temperatures. They (tundra regions) form at around 70° North of the equator only occurring on land and so only found in the Northern Hemisphere. An example of this area is Greenland, where 80 mm of rain falls per year and temperatures range from -29° C to 4° C with only of the year reaching above 0° C.
The winter temperatures average about -30 F throughout most of the true Arctic including the North Pole. The coldest weather occurs in northeastern Siberia. There January temperatures average -40 F, and have reached -93 F. Most other parts of Siberia and the sub arctic sections of central Asia, Canada, and central Alaska have an average winter temperatures of about -20 F. The mildest winters occur in the coastal regions of the Pacific Oceans, where January temperatures average about 30 F.
These same regions have mild summers, with average temperatures of about 45 F. The warmest summers occur in the inland regions of Siberia, Alaska, and Canada. July temperatures there average around 60 F. Weather stations have recorded temperatures of 90 F and above in these regions.
Winter storms develop chiefly in two areas where the barometric pressures remains low. One of these areas, called the Aleutian low, extends from eastern Siberia to the Gulf of Alaska. The other, the Icelandic low, covers central Canada, half of the Arctic Ocean, and parts of the North Atlantic Ocean and northern Europe. Storms beginning in these areas tend to travel from northwest to southwest.
Rainfall in many arctic regions totals six to ten inches a year, including melted snow. This is less rain than falls on some of the world's greatest deserts! Much of the arctic has rain and fog in the summer. In spite of the low annual rainfall, arctic lands may be very wet underfoot because the moisture evaporates slowly and drainage conditions are poor. There is also a lot of permafrost, ice that never goes away in the ground that is usually about five feet deep.
Tundra climate is characterized by harsh winters, low average temperatures, little snow or rainfall, and a short summer season. The arctic tundra, in particular, is influenced by permafrost, a layer of permanently frozen subsoil in the ground. The surface soil, which tends to be rocky, thaws in summer to varying depths. The combination of frozen ground and flat terrain on the tundra impedes the drainage of water. Held at the surface or soaking the upper layer of soil, the water forms ponds and bogs that provide moisture for plants, which helps to make up for the low precipitation.
The tundra regions are cold and freezing places, usually covered in ice making it extremely difficult for plants to grow. Lichens are the ideal plant to grow in the Tundra regions because they can grow on any surface, including bare rock faces. They come in a range of colour like red, yellow, black, orange and green. Lichens are strong and hardy plants that are able to grow where nothing else can grow. Lichens in fact are a combination between two of the most primitive plants, algae and fungi. These two plants live with each other in order to survive. The fungus extracts nutrients from the rock surface to provide moisture for the algae. The algae uses what ever sunlight that it can get hold of, and makes sugars for the fungus to feed upon. As Lichens spread, they help to break up the surface of the rock so they can then grow into finer particles. Lichens are slow growing plants and they come in a variety of species within the Lichen family.
*Various groups of people settled in the tundra area about 10000 years ago (after the Ice Ages)
*Hunters lead a simple life
*Hunters became subsistence hunters and fishing people or nomadic herders wandering with their reindeer, searching for food
*People who were settleing in Tundra areas had to adapt to the climate and the unique way of life
*Inuk ‘a person’
*They call their natural Tundra homeland ‘Nunavut’, and their language ‘Inuktitut’
*Natural vegetation provides Inuit with little food, only a few berries, and it is too cold in the tundra environment to develop crop farming
*Native animals provided them with most of their food, clothing, tools, and even boats and shelter.
*The settlers made up clever methods of hunting animals before there were guns and rifles- like harpoons, spears, bows and arrows, and traps.
*Most of the Inuit lived around the shore-line, where they could also hunt and fish for marine life such as fish (mostly Arctic Char), seals, walrus, whales and polar bears.
*In winter Inuit search for food along the frozen gulfs, channels and Islands and move inland hunting caribou in summer
*Animal furs and caribou hides could be made into warm winter clothing.
*Until recently Inuit didn’t have metal implements, used bone and horn to make harpoon spear-heads, knives, and needles for sewing things together.
*Inuit developed oil lamps using animal fat such as whale blubber.
*The Inuit had no timber so they learnt how to build turf-huts with bone rafters, tents out of caribou skin, and snow block houses called igloos.
*To be able to hunt fish at sea, Inuit built open boats called umiaks, which were the world’s first kayaks, making them out of whale bone and animal skin.
Many Tundra region animals do not remain active during harsh winter months. Animals like ground squirrels and bears remain at a dormant state during the winter until the spring season. Musk oxen and lemmings are some of the few animals that remain active during the winter. Musk oxen are perfectly adapted to the tundra.
Their fur is so long and thick that when it snows or rains on the animal, the skin never gets wet. Lemmings survive using a different approach; they go underground. They dig networks of tunnels under the arctic tundra's soil and line each tunnel with grass to keep them about 0 degrees Celsius. Lemmings live underground fully active until spring. They can even bear young in mid winter.
Some common adaptations of the animals of the Tundra region include:
*short arms and legs.
* a thick, insulating cover of feathers or fur.
* colour changing feathers or fur: brown in summer, and white in winter.
Not only do animals have to keep warm, but also insects needed to develop ways to prevent freezing of their bodily fluids. Like tundra animals, insects also use the sun to keep warm. Insects are also dark in colour and hairy for the same reason animals are. Being small also makes it easier for tundra insects to keep warm.
Animals and insects also have to change their diets depending on the season, other wise they would die of starvation.