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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.
In population ecology and economics, optimum sustainable yield is the level of effort (LOE) that maximizes the difference between total revenue and total cost. Or, where marginal revenue equals marginal cost. This level of effort maximizes the economic profit, or rent, of the resource being utilized.
Theoretically, it is easy to calculate ecological efficiency using the mathematical relationships above. It is often difficult, however, to obtain accurate measurements of the values involved in the calculation. Assessing ingestion, for example, requires knowledge of the gross amount of food consumed in an ecosystem as well as its caloric ...
A farmer can invest a large amount of money to increase his yields by a few percent, for example with an extremely expensive fertilizer, but if that cost is so high that it does not produce a comparative return on investment, his profits decline, and the higher yield can mean a lower agricultural productivity in this case. A yield is a 'partial ...
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").
Resource productivity is the quantity of good or service (outcome) that is obtained through the expenditure of unit resource. [ 1 ] [ 2 ] [ 3 ] This can be expressed in monetary terms as the monetary yield per unit resource.
Productivity in economics is usually measured as the ratio of what is produced (an aggregate output) to what is used in producing it (an aggregate input). [1] Productivity is closely related to the measure of production efficiency. A productivity model is a measurement method
The Solow growth model is a model of economic development into which the Solow residual can be added exogenously to allow predictions of GDP growth at differing levels of productivity growth. The Balassa–Samuelson effect describes the effect of variable Solow residuals: it assumes that mass-produced traded goods have a higher residual than ...