Edaphic Factor 



A condition or characteristic of the soil, physical, chem- 

 ical, or biological that influences organisms, cf. Biotic, Cli- 

 matic, Ecological factor. 



Edaphology 



The study of soils. 



Edaphon 



The aggregate of organisms in the soil except the roots 

 or underground stems of plants, cf. Plankton. 



Edge Effect 



The influence of two communities upon their adjoining 

 margins or fringes, affecting the composition and density of 

 the populations in these bordering areas, e. g., a forest edge 

 bordering a grassland, cf. Ecotone. 



Effective Temperature Range 



The range between the highest and the lowest tempera- 

 ture in which an organism can live. cf. Ecological amplitude, 

 Tolerance. 



Effluent 



The outflow of water from subterranean storage, cf. In- 

 fluent. 



Elaioplast 



A Plastid in which oil is formed and stored. 



Electrolyte 



Salts, acids, or bases that in a solution conduct an electric 

 current, e. g., sodium chloride dissolved in water. 



Element 



(1) Organisms that are typical or characteristic of a cer- 

 tain region, but may occur outside of it, e. g., a group of 

 prairie species occurring in the eastern part of the United 

 States. (2) See Ecological factor. 



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