The rate at which these consumers convert the chemical energy of their food into their own biomass is called secondary productivity. The efficiency at which energy is transferred from one trophic level to another is called ecological efficiency.
Key Features of Biomes
Tundra is the coldest of all the biomes. Tundra comes from the Finnish word tunturia, meaning treeless plain. It is noted for its frost-molded landscapes, extremely low temperatures, little precipitation, poor nutrients, and short growing seasons. 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
- Extremely cold climate
- Low biotic diversity
- Simple vegetation structure
- Limitation of drainage
- Short season of growth and reproduction
- Energy and nutrients in the form of dead organic material
- Large population oscillations
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 subarctic, and these include 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, blackflies 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 tundra is located on mountains throughout the world at high altitude where trees cannot grow. The growing season is approximately 180 days. The nighttime 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:
- Tussock grasses, dwarf trees, small-leafed shrubs, and heaths
- Mammals: pikas, marmots, mountain goats, sheep, elk
- Birds: grouselike birds
- Insects: springtails, beetles, grasshoppers, butterflies
Salient Features of Tundra
The tundra region derives its name from the Finnish word “tunturia,” which means treeless plain. The tundra is characterized by a harsh, frost-laden landscape, minus-zero temperatures, lack of precipitation, nutrients, and extremely short seasons. Divided into two major categories, the artic tundra and alpine tundra, the tundra environment is characterized by a distinct climate, flora and fauna.
The artic is renowned for its cold, desert-like conditions. Winter and summer are its two main seasons, with spring lasting for a short duration between winter and summer. Rainfall varies in different artic regions, and yearly precipitation including melting snow, is around 6 to 10 inches. Summer temperatures in the artic tundra range between 37 to 54 degrees Fahrenheit, and winter temperatures average around minus-29 degrees Fahrenheit.
Flora and Fauna
Characterized by low-nutrient soil with sparse vegetation, the artic tundra is home to around 1,700 different species of shrubs, sedges, mosses, lichens, grasses and 400 varieties of flowers.
Plants are adapted to sweeping winds and soil disturbances, growing short and grouping together to resist the cold temperatures. The growing season lasts for around 50 to 60 days. With the exception of birch trees in the lower latitudes, no other trees inhabit the artic tundra.
Since the ground is always frozen beneath the soil’s top layer, trees cannot send roots down. Willows grow in some tundra regions, but only as low carpets around 3 inches high.
Tundra animal life is restricted to the challenging environment, and reptiles and amphibians do not exist in this habitat. According to the Physical Geography web site, the caribou, musk ox, arctic hare, voles and lemmings are the principal herbivores, which enable a few carnivores like the arctic fox, snow owl, polar bear, and wolf to survive.
Global Warming & Tundra Climate
Large swaths of the Arctic tundra will be warm enough to support lush vegetation and trees by 2050. Higher temperatures will lessen snow cover, which, in turn, will decrease the sunlight reflected back into the atmosphere and increase warming. About half the areas will see vegetation change, and areas currently populated by shrubs may find woody trees taking their place.
One can substitute the snowy surface with the darker surface of a coniferous tree for example, and the darker surface of the tree will store more heat. It is going to exacerbate warming.
Oil Drilling in Tundra
The oil and gas industry wants access to areas both on land (the Arctic Wildlife Refuge) and in the Arctic Ocean (the Chukchi and Beaufort seas), even though oil and gas development would carve up the Arctic Refuge with roads and industrial infrastructure, fragmenting otherwise pristine habitat and exposing the fragile tundra and wildlife to toxic chemicals and oil spills.
Currently, oil and gas companies, including Shell, are attempting to begin drilling operations in the Arctic Ocean. Offshore drilling threatens the sensitive coasts of both the Arctic Refuge and the Western Arctic Reserve. With the oil and gas industry lacking technology to safely operate or recover spilled oil in one of the harshest environments on Earth, these proposals are dangerous. Despite what oil companies say, oil spills are part of drilling. In the Chukchi alone, the government has predicted a 40 percent chance of a significant oil spill.
The Chukchi and Beaufort seas are home to polar bears, several species of seals and whales, millions of birds and 90 percent of the entire Pacific walrus population. An oil spill could devastate critical feeding grounds for these animals, and put them in direct danger of exposure to oil through oil spills. Arctic ecosystems are less likely to recover from spills than those in more temperate climates. Oil breaks down slower in cold weather, while shorter growth and reproduction seasons means that negative impacts persist longer.