| 单词 | pyramid of numbers |
| 释义 | > as lemmaspyramid of numbers 11. Ecology. An ecological system conceived as a series of trophic levels with many small prey animals (or primary producers) forming the base of a pyramid and a few large predators forming the apex; a diagram representing such a system as a stack of horizontal bars, each of a length proportional to the numbers, biomass, etc., at the corresponding trophic level. Originally and esp. in pyramid of numbers. ΚΠ 1927 C. Elton Animal Ecol. v. 70 This arrangement of numbers in the community, the relative decrease in numbers at each stage in a food-chain, is characteristically found in animal communities all over the world, and to it we have applied the term ‘pyramid of numbers’. 1940 Amer. Midland Naturalist 24 179 This periodic change in animal protein is notable in that it increases the food supply in the upper third of the Eltonian pyramid. 1958 Biometrics 14 386 [It is] only because birds are so high in the ecological pyramid that their densities related to the available foraging area are relatively so low. 1973 P. A. Colinvaux Introd. Ecol. ix. 132 The distribution as well as the abundance of animals was reflected in the pyramid of numbers, the larger animals being more wide ranging as well as less numerous than the small animals. 1987 BioScience 37 613/2 In talking of ecology, pyramids of energy content are confused with..pyramids of energy flow. The former are just minor variants of pyramids of biomass, and..thermodynamics does not dictate any taper in successively higher levels. 1997 Jrnl. Biogeogr. 24 704/1 The number of carnivorous species of mammals..is less than the number of herbivorous species on the same islands, reflecting the Eltonian pyramid. < as lemmas |
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