Biomes (Encyclopedia of Environmental Issues, Revised Edition)
Each of the earth’s biomes has a typical ecological pattern, with its flora and fauna sharing similar characteristics, such as leaf forms and survival strategies. A study of any biome, on any continent, will show multiple ways its species carry out the essential tasks of life. Biomes are large and complex, with species forming intricate networks of life within subsets of the biomes.
Land-based major biomes include the following: tropical rain forest, tropical dry forest, savanna (tropical grassland), desert, temperate grassland, Mediterranean scrub or chaparral, temperate deciduous forest, temperate mixed and coniferous forest, boreal forest(taiga), and Arctic tundra. Marine biomes are basically characterized as oceanic or freshwater, although the lack of vegetation-climate links and the gradients between coastal and deep-sea habitats make the simplicity of this scheme problematic. Finally, human activities have so transformed large portions of the earth that some biologists treat anthropogenic (human-dominated) biomes as a separate concept. These biomes range from dense settlement patterns in urban landscapes to cropland, rangeland, and forest.
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Influences on Biomes (Encyclopedia of Environmental Issues, Revised Edition)
Biomes are sometimes viewed as giant ecosystems. Because of biomes’ size and complexity, however, both scientists and lay observers find it more useful to view biomes as made up of many different ecosystems and habitats.
Land-based biomes are shaped largely by their climates. The most important climatic factors are latitude and humidity (total precipitation, seasonal rainfall patterns, ambient moisture); sometimes elevation is important also. Cross-cutting these climatic factors—though influenced by them—are such features as terrain, soil type and nutrient status, and prevailing winds. All these affect the kinds of vegetation that can flourish in a region, thus determining the types and amounts of animal life the plant cover will support.
Generally biomes closer to the equator support more biodiversity, in the form of different species. An estimated 50 percent of all life-forms on earth are native to tropical forests. Tropical rain forests also have many layers of life systems, from the canopy ecosystems with their monkeys, marmosets, and tropical birds, such as macaws, down through several canopy-gap layers that shelter opossums and woodpeckers, to the forest floor, the base station for jaguars and frogs, among other jungle dwellers. What the tropical forests do not have is a rich nutrient base. They have poor soil quality, and most of the available nutrients are held within the trees themselves rather than...
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Environmental Issues and Biomes (Encyclopedia of Environmental Issues, Revised Edition)
For the nonhuman organisms living in any given biome, the environmental features of that biome are essential to life. Human beings, in contrast, interact with biomes by finding ways to use the biomes’ natural resources to sustain them. Human technologies and large numbers of humans, however, can upset a delicately balanced biome far beyond its ability to recover. Even in the ancient world, large-scale grazing and firewood collection apparently turned once-wooded coastal areas into the Mediterranean scrub that bears that region’s name.
Throughout history, humans have cleared forests or modified grasslands for use in agriculture. Sometimes the environmental damage done by such processes is limited. For example, the prairie grasslands of the American Great Plains were originally roamed by bison, and the cattle herds that replaced the bison filled the same ecological niche. Other human-caused changes have brought near disaster to entire biomes.
Human activities have altered every one of the earth’s biomes. Among the most dire changes has been the destruction of tropical forests caused by timber harvesting and by the clearing of trees and other plant life to make way for ranching or industry. The damage caused when a biome is altered is not confined to the loss of diverse natural resources within that biome; rather, such change threatens the entire biosphere because it interferes with the role the...
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Further Reading (Encyclopedia of Environmental Issues, Revised Edition)
Butz, Stephen D. Science of Earth Systems. 2d ed. Clifton Park, N.Y.: Thomson Delmar Learning, 2008.
Whitfield, Philip, Peter D. Moore, and Barry Cox. Biomes and Habitats. New York: Macmillan, 2002.
Woodward, Susan L. Biomes of Earth: Terrestrial, Aquatic, and Human-Dominated. Westport, Conn.: Greenwood Press, 2003.
_______. Introduction to Biomes. Westport, Conn.: Greenwood Press, 2009.
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Background (Encyclopedia of Global Resources)
Biomes are natural habitats for bacteria, protists, fungi, plants, and animals. Biomes maintain the natural life cycle of these organisms and preserve the products of geological processes on Earth. A biome is a source of shelter, rocks and minerals, and food and fiber for human needs.
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Technical Definition (Encyclopedia of Global Resources)
A terrestrial biome is a large ecosystem characterized by a particular type of climate and soils with defined groups of highly adapted living organisms. Biome formation is influenced by warm temperature and heavy precipitation in the tropics and extreme cold and low precipitation near the poles. Most ecologists do not consider aquatic ecosystems as biomes and refer to them as “aquatic biomes,” which are classified based on the concentration of dissolved salts: less than 0.1 percent in freshwater biomes, 0.1 to 1.0 percent in estuaries, and more than 1.0 percent in marine biomes.
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Climate and Biomes (Encyclopedia of Global Resources)
Climate shapes terrestrial biomes. Climate is predominantly driven by the solar energy and atmospheric circulation. Air circulation is initiated at the equator, because the equator receives the greatest solar energy with the warmest air near the ground. Because of different air densities, warm air in the troposphere rises into the stratosphere and cools. Cool air in the stratosphere descends into troposphere and warms. This rise and fall pattern of circulating air starts at 0° (equator) to 30° latitude, then continues at 30° to 60° latitude, and ends at 60° to 90° latitude (poles).
There are six major atmospheric circulations: Three move from the equator to the North Pole; the other three move from the equator to the South Pole. At 0° latitude, the ascending warm, humid air from the troposphere cools and condenses as it reaches the stratosphere, releasing heavy rain to or near the equator. That the dominant biomes formed at the equator are the tropical rain forests is no accident. After releasing rain, the cool, dry air moves poleward and descends at 30° latitude. The descending cool, dry air becomes warm as it reaches the troposphere and then absorbs all the available moisture. Not surprisingly, the dominant biomes at 30° latitude are the deserts, where the warm, humid air splits. One air mass moves equatorward to recirculate at 0° latitude. The other moves poleward and rises at 60° latitude, releasing rain or...
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Terrestrial Biomes (Encyclopedia of Global Resources)
The are nine major terrestrial biomes.
Arctic Tundra. Arctic tundra is located in the Northern Hemisphere near the North Pole and covers 20 percent of Earth’s landmass. It has extremely long, freezing, and harsh winters, with very short (six-to eight-week) summers. It is considered “cold desert,” because it receives 20 centimeters of precipitation per year. Melting snow creates bogs in summer, but there are frozen layers of subsoil (permafrost) at least a meter deep that exist throughout the year. Soil is nutrient-poor. Only the low-growing grasses and dwarf woody shrubs adapted to extreme cold and a short growing season are found. No trees survive. Their roots cannot penetrate the permafrost. Few animal species live in tundra. In winters, ptarmigans, musk oxen, snowy owls, lynxes, arctic foxes, and snowshoe hares are found. Polar bears are common in the coastal regions. In summers, few migrating animals from taiga move to tundra. No reptiles are found, but mosquitoes survive.
Taiga. Taiga, also called boreal coniferous forest, exists south of tundra and covers 11 percent of the Earth’s land surface. It is found in the northern parts of North America and Eurasia and along the Pacific coast of northern North America to Northern California. It has patchy and shallower permafrost than tundra, and has acidic, nutrient-poor soil. It has short summers and long, cold winters and...
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Aquatic Biomes (Encyclopedia of Global Resources)
All aquatic biomes share three ecological groups of organisms: the plankton, nekton, and benthos. Plankton are classified into microscopic phytoplankton and large zooplankton. Phytoplankton are producers and include photosynthetic cyanobacteria and free-floating algae, which provide oxygen and food for heterotrophic organisms. Zooplankton are consumers, heterotrophic, nonphotosynthetic organisms that include protozoa, small crustaceans, and larvae of aquatic animals. Nekton are larger swimming animals such as turtles, fishes, and whales. Benthos are bottom-dwelling animals that attach themselves to a substratum (sponges, oysters, and barnacles), burrow themselves into soil (clams, worms, and echinoderms) or simply swim or walk on the bottom (crayfish, crabs, lobsters, insect larvae, and brittle stars).
Based on salt contents, the three major aquatic ecosystems are the freshwater, estuary, and marine ecosystems.Freshwater ecosystems, which contain less than 0.1 percent dissolved salts and occupy about 2 percent of the Earth’s surface, include flowing waters (streams and rivers), standing waters (ponds and lakes), and freshwater wetlands (marshes and swamps). While all freshwater habitats provide homes for animal species, greater vegetations are found in marshes (grasslike plants) and in swamps (trees and shrubs) than in flowing- and standing-water ecosystems. Estuaries occur where fresh water and salt water meet, with salt...
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History (Encyclopedia of Global Resources)
The existence of aquatic and terrestrial ecosystems was discovered through fossil records. Aquatic biomes emerged before the terrestrial biomes. Approximately 542 million years ago, during the Cambrian period, organisms in marine biomes became diversified and included bacteria, cyanobacteria, algae, fungi, marine invertebrates, and first chordates. The first terrestrial biome existed when the first forest and gymnosperm appeared about 416 million years ago, during the Denovian period. About 359 million years ago, during the Carboniferous period, the formation of much more diversified forest occurred, which consisted of ferns, clubmosses, horsetails, and gymnosperms and which housed many insects, amphibians, and first reptiles. Flowering plants (angiosperms) later evolved and became the dominant organisms of most major biomes.
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Further Reading (Encyclopedia of Global Resources)
Kirchner, Renee. Biomes. Detroit: KidHaven Press/Thomson Gale, 2006.
Roth, Richard A. Freshwater Aquatic Biomes. Westport, Conn.: Greenwood Press, 2009.
Solomon, Eldra Pearl, Linda R. Berg, and Diana W. Martin. “Ecology and the Geography of Life.” In Biology. 8th ed. Monterey, Calif.: Brooks/Cole, 2008.
Woodward, Susan L. Marine Biomes. Westport, Conn.: Greenwood Press, 2008.
University of California Museum of Paleontology. http://www.ucmp.berkeley.edu/exhibits/biomes/index.php
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Biomes (Science Experiments)
Life in the desertith air conditioning
Building a Temperate Forest Biome
Summary of Results
Design Your Own Experiment
If you have ever hiked in a forest or driven through a desert, what you saw was a biome. are large geographical areas with specific climates and soils, as well as distinct plant and animal communities that are all interdependent.
Most biomes are on land. Our oceans make up a single biome. Besides temperateMild or moderate weather conditions. forest and desert, the major land biomes include , taigaA large land biome mostly dominated by coniferous trees. (pronounced TIE-gah, temperate (pronounced deh-SID-you-us) forest, tropical rainforest, and grassland. To understand how biomes work, let us look at some of them.
Maybe you have hiked in a taiga biome, the biome that receives the most snow. Unlike its neighboring biome, the tundra, which is treeless and characterized by low-lying plants, the taiga is sometimes called the (pronounced BORE-e-al)
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