o They get energy from detritus nonliving organic material such as the remains

O they get energy from detritus nonliving organic

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o They get energy from detritus, nonliving organic material such as the remains of dead organisms, feces, fallen leaves, and wood. o Detritivores play an important role in material cycling. Decomposition connects all trophic levels. The organisms that feed as detritivores form a major link between the primary producers and the consumers in an ecosystem. Detritivores play an important role in making chemical elements available to producers. o Detritivores decompose organic material and transfer chemical elements in inorganic forms to abiotic reservoirs such as soil, water, and air. Producers then recycle these elements into organic compounds. An ecosystem’s main decomposers are fungi and prokaryotes. Concept 54.2 Physical and chemical factors limit primary production in ecosystems The amount of light energy converted to chemical energy by an ecosystem’s autotrophs in a given time period is an ecosystem’s primary production. An ecosystem’s energy budget depends on primary production. Most primary producers use light energy to synthesize organic molecules, which can be broken down to produce ATP. The amount of photosynthetic production sets the spending limit of the entire ecosystem. A global energy budget can be analyzed. o Every day, Earth is bombarded by approximately 1023 joules of solar radiation. The intensity of solar energy striking Earth varies with latitude, with the tropics receiving the greatest input. Most of this radiation is scattered, absorbed, or reflected by the atmosphere. Much of the solar radiation that reaches Earth’s surface lands on bare ground or bodies of water that either absorb or reflect the energy. Only a small fraction actually strikes algae, photosynthetic prokaryotes, or plants, and only some of this is of wavelengths suitable for photosynthesis. Of the visible light that reaches photosynthetic organisms, only about 1% is converted to chemical energy. o Although this is a small amount, primary producers produce about 170 billion tons of organic material per year. Total primary production in an ecosystem is known as gross primary production (GPP). o This is the amount of light energy that is converted into chemical energy per unit time. Plants use some of these molecules as fuel in their own cellular respiration. Net primary production (NPP) is equal to gross primary production minus the energy used by the primary producers for respiration (R): NPP = GPP - R To ecologists, net primary production is the key measurement, because it represents the storage of chemical energy that is available to consumers in the ecosystem. Primary production can be expressed as energy per unit area per unit time, or as biomass of vegetation added to the ecosystem per unit area per unit time.
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o This should not be confused with the total biomass of photosynthetic autotrophs present in a given time, which is called the standing crop.
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