number of plots, uniform in area, located in a number of 

 stands of one kind of Community-type or Abstract commun- 

 ity, cf. Presence. 



Constants of a Community or Association 



The species which show the highest degrees of Con- 

 stancy (q. v.); the most usual lower limit is 80 per cent, but 

 varies from 50 to 90 per cent, according to various schools. 



Constructive (Species) 



Refers to plants whose Reactions or Coactions aid in the 

 development or persistence of a Community. 



Consumer Organisms (Consumers) 



Organisms which ingest other organisms or food par- 

 ticles, may be classified as primary, secondary, etc., depend- 

 ing upon their position in the Food chain (q. v.) or the 

 Trophic level (q. v.). cf. Producers. 



Consumptive Use 



The quantity of water used and transpired by vegetation 

 plus the amount lost by evaporation, syn. Evapotranspiration. 



Contagious Dispersion 



The non-random (above normal) occurrence of indi- 

 viduals of a species, forming aggregations, syn. over-disper- 

 sion, Hyperdispersion. cf. Normal dispersion, Hypodisper- 

 sion. 



Continental Bridge Hypothesis 



The hypothesis that the present-day continents were 

 once connected by isthmuses, or other areas of land. 



Continental Drift Hypothesis 



The hypothesis, advanced especially by Wegener, that 

 the presentnday continents were displaced horizontally from 

 the original mass of land to their present positions. 



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