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Biomass

Biomass

Suppose you take a walk in the forest one day and you look around you at all the trees and think, "That's a lot of wood, I wonder how much all these trees weigh?" Biologists ask the same question. Biomass is the total mass of all the trees (after the water has been taken out).

The term "biomass" is actually applied to three related but slightly different concepts. The total dry weight of all living organisms that can be supported at each trophic level in a food chain is known as the biomass. The term is also applied to the dry weight of all living organic matter in an entire ecosystem. Finally, people interested in alternative sources of energy use the term to apply to the total mass of all plant materials and animal wastes that can be used as fuel.

Plants use a complex chemical process known as photosynthesis to combine carbon dioxide, water, and sunlight to produce carbohydrates (sugar and cellulose), fats, and proteins. The solar energy that drives photosynthesis is stored in the chemical bonds of these molecules. These carbohydrates, fats, and proteins make up biomass. Biomass, then, can be considered to be stored solar energy.

The energy stored in carbohydrates and other compounds by photosynthesis can be released by burning or by metabolism. When animals eat plants, their bodies slowly release the energy stored in the chemical bonds and this energy becomes available to the animals for muscular activity or maintaining body temperature. When biomass is burned, the water and carbon dioxide are released back into the atmosphere. Therefore, biomass is a renewable energy resource.

The total amount of biomass produced each year is about eight times the world's energy consumption. However, the energy density of each unit of biomass is much smaller than the energy content of fossil fuels ("old" biomass), so much more mass must be burned to produce the same amount of energy. Also, the world's biomass is widely distributed, so concentrating and transporting the biomass remains a problem. There are experimental projects that convert biomass into alcohol or natural gas. But worldwide, only about 7 percent of the biomass produced each year is used as fuel, so this energy resource remains underutilized.

The amount of biomass generally decreases at each higher trophic level. In a temperate grassland, for example, the amount of biomass at each trophic level is only about 10 percent of the biomass of the level below it. If there are 10,000 kilograms (22,000 pounds) of producers (grasses and other plants), there will be only 1,000 kilograms of primary consumers (grasshoppers, voles, bison), 100 kilograms of secondary consumers (shrews, hawks, small cats), and only 10 kilograms of tertiary consumers (large cats, wolves, humans).

The remaining 90 percent of the available energy from biomass at each level is converted to waste heat. This energy loss at each trophic level generally limits food chains to no more than four or five levels.

Marine environments usually reverse the amounts of biomass in the first two trophic levels. The mass of primary consumers (small fish and shrimp) is generally much larger than the mass of producers. This happens because the primary producers are tiny phytoplankton that grow and reproduce rapidly instead of large plants that grow and reproduce slowly.

see also Biomes; Food Web.

Elliot Richmond

Bibliography

Curtis, Helena, and N. Sue Barnes. Biology, 5th ed. New York: Worth Publishing, 1989.

Miller, G. Tyler, Jr. Living in the Environment, 6th ed. Belmont, CA: Wadsworth Publishing Company, 1990.

Purves, William K., and Gordon H. Orians. Life: The Science of Biology. Sunderland, MA: Sinauer Associates, 1987.

American Bioenergy Association

This interest group located in Washington D.C., works to promote the use of bioenergy resources as alternative energy sources. The ABA strives to gain support through the federal government by proposing policies such as tax incentives, increased budget allocations, and research funding. The ABA argues that using biomass would cut U.S. dependence on oil from the Persian Gulf, and fuel the nation's economy.

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biomass

biomass Total mass (excluding water content) of the plants and/or animals in a particular place. The term is often used to refer to the totality of living things on Earth; or those occupying a part of the Earth, such as the oceans. It may also refer to plant material that can be exploited, either as fuel or as raw material for an industrial or chemical process.

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biomass

biomass(standing crop) The total mass of all living organisms (producers, consumers, and decomposers) or of a particular set (e.g. species), present in an ecosystem or at a particular trophic level in a food-chain, and usually expressed as dry weight or, more accurately, as the carbon, nitrogen, or calorific content per unit area.

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"biomass." A Dictionary of Ecology. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

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"biomass." A Dictionary of Ecology. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/biomass

biomass

biomass The total mass of all the organisms of a given type and/or in a given area; for example, the world biomass of trees, or the biomass of elephants in the Serengeti National Park. It is normally measured in terms of grams of dry mass per square metre. See also pyramid of biomass.

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biomass

biomass The total mass of all living organisms, or of a particular set (e.g. species), present in a habitat or at a particular trophic level in a food chain, and usually expressed as dry weight or, more accurately, as the carbon, nitrogen, or calorific content, per unit area.

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biomass

bi·o·mass / ˈbīōˌmas/ • n. the total mass of organisms in a given area or volume. ∎  organic matter used as a fuel, esp. in a power station for the generation of electricity.

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biomass

biomass (standing crop) The total weight of the living components (producers, consumers, and decomposers) in an ecosystem at any moment, usually expressed as dry weight per unit area.

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"biomass." A Dictionary of Plant Sciences. . Encyclopedia.com. 20 Aug. 2017 <http://www.encyclopedia.com>.

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"biomass." A Dictionary of Plant Sciences. . Retrieved August 20, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/biomass-0

biomass

biomassalas, Alsace, amass, ass, Bass, chasse, crass, crevasse, en masse, gas, Hamas, lass, mass, morass, sass, tarantass, tass, wrasse •Díaz • Phidias • palliasse •materfamilias, paterfamilias •Asturias • Aphrodisias • Trias •Donbas • Vargas • Ofgas • biogas •teargas • jackass • Hellas • Ulfilas •Stanislas • Candlemas • landmass •Martinmas • biomass • Childermas •Esdras • Mithras • hippocras •sassafras • demitasse • gravitas

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