Research On Tundra Biome

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 Food Webs and Energy Flow

As in most ecosystems, energy enters the tundra ecosystem in the form of sunlight. The polar tundra is unusual, however, in the way sunlight is distributed over the course of time. In the polar tundra summer, the days become very long and the nights very short. Between the Arctic and Antarctic Circles and the poles there is no night at all for part of the year. In the polar winter, on the other hand, there is little daylight or none at all for part of the time. Day length in alpine tundra varies seasonally according to how far north or south of the equator it is found. Close to the equator there is very little seasonal variation in day length.

The duration of daylight affects the amount of photosynthesis that green plants can achieve. They continue to respire during the hours of darkness, so if day length becomes very short, plants may lose more energy in respiration than they are producing by photosynthesis, in which case they have to draw upon stored food reserves to sustain life. Many plants, therefore, enter a period of dormancy throughout the polar winter so that they can reduce respiration losses of energy to a minimum. Even in alpine tundra, plants may respond to low temperature and snow cover with a winter shutdown rather than try to maintain low levels of productivity.

The short growing season of the tundra ecosystem means that the total amount of primary production (the overall carbon-fixation by green plants) occurring in the course of a year is relatively small compared to that of other ecosystems. It is not easy to measure primary production accurately for a number of reasons. Some of the energy that accumulates is in the form of roots, and root growth is not easily measured. Parts of plants become detached and decomposed, so ecologists have to make allowances for the losses of litter and the death of roots. Animals, including invertebrates, are constantly consuming plants, so energy is moving along the food webs all the time and is not left to accumulate in the growing plants. Despite all these problems, ecologists have now built up many separate estimates of primary productivity from the various biomes of the world. Generally these estimates are expressed in terms of how much dry weight of plant material accumulates in a specific area of an ecosystem in the course of a year. Dry weights are used because different plants contain different amounts of water, regardless of the amount of energy present. Strictly speaking, it would be better to express productivity data in the form of energy accumulated rather than weight, and sometimes this is done, but weight of plant material is normally used because the variation in energy content of different plant materials is not normally a source of great error.

Tundra vegetation, already described, is very variable. There are locations where vegetation is unable to survive, and these areas will have no productivity at all. The amount of annual dry matter productivity found within vegetated Arctic tundra habitats ranges from 0.25 to 0.42 pounds per square yard (0.14 to 0.23 kg/m²). Alpine tundra productivity is similar, usually below a value of 0.5 pounds per square yard (0.3 kg/m²). This is very low productivity compared with a tropical rain forest, which has an annual productivity of about 5.4 pounds per square yard (3 kg/m²), or even a temperate deciduous forest yielding 1.8 pounds per square yard (1 kg/m²). It is very similar, however, to the value for annual productivity found in the hot dry deserts of the world. From a productivity point of view, therefore, the tundra ecosystem is equivalent to a desert.

Ecosystems with low primary productivity generally support a limited amount of animal life and have a relatively poor biodiversity, and this is true of the tundra. The diagram illustrates the type of food web that is found within tundra ecosystems.

Conclusions

The tundra can be viewed as an ecosystem because the animals, plants, and microbes that it contains function as an integrated unit, interacting with their chemical and physical setting. Using the ecosystem approach to the study of tundra, it is possible to trace the processes of energy flow and nutrient cycling that link the living and nonliving components of the system.
The energy input from the Sun is relatively low in tundra ecosystems when compared with those of all other biomes, and it is strongly seasonal in its distribution. Polar sites undergo a prolonged winter in which energy input is very low or completely absent. Low temperature in the winter season reduces the primary productivity in both polar and alpine tundra. As a result, energy flow in the tundraecosystem is limited and consequently there are relatively few links in food chains and food webs. The outcome of these energy limitations is that the number of different types of living organisms that can exist in tundra is restricted.
Nutrient cycling between vegetation and soil is limited by the rate of decomposition, and this is affected by temperature and wetness. Under conditions of low temperature or water-logging there is reduced microbial activity and hence low decomposition. As a result, some elements are locked up in dead organic matter in the ecosystem and are not released for recycling. This slows down the process of nutrient cycling and may restrict plant growth and consequently herbivore abundance.

The low biodiversity, soil instability, and restricted nutrient cycling combine to make the tundra ecosystem relatively fragile. It lacks inertia, so it is easily damaged, and it is not very resilient, so it does not recover quickly from disturbance.

Citation: Moore, P. D. Tundra ecosystem. In Science online. Retrieved from http://www.fofweb.com.libproxy.nlb.gov.sg/activelink2.asp?ItemID=WE40&SID=5&iPin=BETDR0003&SingleRecord=True

Tundras are among Earth's coldest, harshest biomes. Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy and rainfall is scant. Tundra lands are snow-covered for much of the year, until summer brings a burst of wildflowers.

Mountain goats, sheep, marmots, and birds live in mountain, or alpine, tundra and feed on the low-lying plants and insects. Hardy flora like cushion plants survive on these mountain plains by growing in rock depressions where it is warmer and they are sheltered from the wind.

The Arctic tundra, where the average temperature is 10 to 20 degrees Fahrenheit (-12 to -6 degrees Celsius), supports a variety of animal species, including Arctic foxes, polar bears, gray wolves, caribou, snow geese and musk-oxen. The summer growing season is just 50 to 60 days, when the sun shines 24 hours a day.

The few plants and animals that live in the harsh conditions of the tundra are essentially clinging to life. They are highly vulnerable to environmental stresses like reduced snow cover and warmer temperatures brought on by global warming.

The Arctic tundra is changing dramatically due to global warming. Already, more southern animals like the red fox have moved onto the tundra. The red fox is now competing with the Arctic fox for food and territory, and the long-term impact on the sensitive Arctic fox is unknown.

It is the Arctic's permafrost that is the foundation for much of the region's unique ecosystem, and it is the permafrost that is deteriorating with the warmer global climate. Permafrost is a layer of frozen soil and dead plants that extends some 1,476 feet (450 meters) under the surface. In much of the Arctic it is frozen year round. In the southern regions of the Arctic, the surface layer above the permafrost melts during the summer and this forms bogs and shallow lakes that invite an explosion of animal life. Insects swarm around the bogs, and millions of migrating birds come to feed on them.

With global warming, the fall freeze comes later and more of the permafrost is melting in the southern Arctic. Shrubs and spruce that previously couldn't take root on the permafrost now dot the landscape, potentially altering the habitat of the native animals.

Another major concern is that the melting of the permafrost is contributing to global warming. Estimates suggest that about 14 percent of the Earth’s carbon is tied up in the permafrost. Until recently, the tundra acted as a carbon sink and captured huge amounts of carbon dioxide from the atmosphere as part of photosynthesis. This process helped keep the amount of this greenhouse gas from accumulating in the atmosphere.

Today, however, as the permafrost melts and dead plant material decomposes and releases CO2, the tundra has flipped from a carbon sink to a carbon contributor.

From: http://environment.nationalgeographic.com/environment/habitats/tundra-profile/







Thus, I can infer that the habitat has:

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
8. a vast and treeless land
9. The energy input from the Sun is relatively low

1. Since the habitat is extremely cold, I gave my organism a thick layer of furs
2. Since habitat has little food source, I gave my organism a hump to store food.
3. Since habitat is white, my organism should be white in colour to camouflage with the surroundings.