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The Food and Agriculture Organization (FAO) Food Price Index 1961–2021 in nominal and real terms. The Real Price Index is the Nominal Price Index deflated by the World Bank Manufactures Unit Value Index (MUV). Years 2014–2016 is 100. Food prices refer to the average price level for food across countries, regions and on a global scale. [1]
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.
The number of trophic links per consumer is a measure of food web connectance. Food chains are nested within the trophic links of food webs. Food chains are linear (noncyclic) feeding pathways that trace monophagous consumers from a base species up to the top consumer, which is usually a larger predatory carnivore. [8] [9] [10]
Decomposers are often left off food webs, but if included, they mark the end of a food chain. [6] Thus food chains start with primary producers and end with decay and decomposers. Since decomposers recycle nutrients, leaving them so they can be reused by primary producers, they are sometimes regarded as occupying their own trophic level.
A price index aggregates various combinations of base period prices (), later period prices (), base period quantities (), and later period quantities (). Price index numbers are usually defined either in terms of (actual or hypothetical) expenditures (expenditure = price * quantity) or as different weighted averages of price relatives ( p t ...
The rate of biomass production of an organism is required, which involves measuring growth and reproduction through time. There is still the difficulty of assigning the organisms to a specific trophic level. As well as the organisms in the food chains there is the problem of assigning the decomposers and detritivores to a particular level.
Food chain in a Swedish lake. Osprey feed on northern pike, which in turn feed on perch which eat bleak which eat crustaceans.. A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as earthworms and woodlice ...
The Food and Agriculture Organization (FAO) Food Price Index 1961–2024 in nominal and real terms. Years 2014–2016 is 100. The FAO Food Price Index (FFPI) is a food price index by the Food and Agriculture Organization (FAO) of the United Nations. It records the development of world market prices of 24 agricultural commodities and foodstuffs ...