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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").
The productivity of autotrophs, such as plants, is called primary productivity, while the productivity of heterotrophs, such as animals, is called secondary productivity. [ 1 ] The productivity of an ecosystem is influenced by a wide range of factors, including nutrient availability, temperature, and water availability.
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 ...
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 ...
However, autochthonous (coming from within the ecosystem) pathways also remain important to metabolism in heterotrophic ecosystems. In an autotrophic ecosystem, conversely, primary production (by algae, macrophytes) exceeds respiration, meaning that ecosystem is producing more organic carbon than it is respiring.
In the first quarter of 2022, U.S. worker productivity fell in the steepest drop in 74 years. WSJ’s Jon Hilsenrath explains why productivity is central to the economy, and why big drops can be ...
While generally low, observed primary productivity in gyres is higher than would be expected based on measured nutrient supply. [37] The excess primary production can be explained by nitrogen fixing organisms that supply the remaining bioavailable nitrogen needed to support observed seasonal primary productivity.
Net ecosystem production (NEP) in ecology, limnology, and oceanography, is the difference between gross primary production (GPP) and net ecosystem respiration. [1] Net ecosystem production represents all the carbon produced by plants in water through photosynthesis that does not get respired by animals, other heterotrophs, or the plants themselves.