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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").
Terrestrial primary productivity refers to the organic matter production that takes place in terrestrial ecosystems such as forests, grasslands, and wetlands. Primary production is divided into Net Primary Production (NPP) and Gross Primary Production (GPP).
Out of a total of 28,400 terawatt-hours (96.8 × 10 ^ 15 BTU) of energy used in the US in 1999, 10.5% was used in food production, [3] with the percentage accounting for food from both producer and primary consumer trophic levels. In comparing the cultivation of animals versus plants, there is a clear difference in magnitude of energy efficiency.
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.
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 ...
The primary factors facilitate production but neither become part of the product (as with raw materials) nor become significantly transformed by the production process (as with fuel used to power machinery). Land includes not only the site of production but also natural resources above or below the soil.
Gross domestic product (GDP) is defined as "the value of all final goods and services produced in a country in 1 year". [3] Gross national product (GNP) is defined as "the market value of all goods and services produced in one year by labour and property supplied by the residents of a country." [4]
On the other hand, this particular textbook definition of Primary Production does not contain reference to time, so I believe that it directly contradicts the statements in the "Gross primary production and net primary production" section that these quantities are rates (units of mass per unit area per unit time interval). In other words, the ...