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Gross primary production (GPP) is the amount of chemical energy, typically expressed as carbon biomass, that primary producers create in a given length of time.Some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues (i.e., "growth respiration" and "maintenance respiration").
Aquatic primary productivity refers to the production of organic matter, such as phytoplankton, aquatic plants, and algae, in aquatic ecosystems, which include oceans, lakes, and rivers. Terrestrial primary productivity refers to the organic matter production that takes place in terrestrial ecosystems such as forests, grasslands, and wetlands.
The production process and output directly result from productively utilising the original inputs (or factors of production). [3] Known as primary producer goods or services, land, labour, and capital are deemed the three fundamental factors of production. These primary inputs are not significantly altered in the output process, nor do they ...
Gross primary production is a measure of the energy that a photoautotroph harvests from the sun. Take, for example, a blade of grass that takes in x joules of energy from the sun. The fraction of that energy that is converted into glucose reflects the gross productivity of the blade of grass. The energy remaining after respiration is considered ...
Upwelling regions therefore result in very high levels of primary production (the amount of carbon fixed by phytoplankton) in comparison to other areas of the ocean. They account for about 50% of global marine productivity. [9] High primary production propagates up the food chain because phytoplankton are at the base of the oceanic food chain. [10]
A pyramid of energy or pyramid of productivity shows the production or turnover (the rate at which energy or mass is transferred from one trophic level to the next) of biomass at each trophic level. Instead of showing a single snapshot in time, productivity pyramids show the flow of energy through the food chain. Typical units are grams per ...
Labor, not labor power, is the key factor of production for Marx and the basis for earlier economists' labor theory of value. The hiring of labor power only results in the production of goods or services ("use-values") when organized and regulated (often by the "management"). How much labor is actually done depends on the importance of conflict ...
Marine primary production is the chemical synthesis in the ocean of organic compounds from atmospheric or dissolved carbon dioxide. It principally occurs through the process of photosynthesis , which uses light as its source of energy, but it also occurs through chemosynthesis , which uses the oxidation or reduction of inorganic chemical ...