Aspect 



(1) One of the seasonal appearances of vegetation. See 

 Aspection. (2) The direction toward which a slope faces. 



Aspection 



The variability in the appearance of vegetation or of its 

 constituent parts such as blooming, fruiting, foliation, and 

 defoliation during the various seasons of the year. Chief 

 seasons are Prevernal* Vernal, Estival, Serotinal, and Hibernal 

 (q. v.). 



Assimilation 



The synthesis of protoplasm and other complex sub- 

 stances by organisms. 



Association 



A term with a number of usages, some of which are 

 defined. (1) An actual or Concrete community, Stand, or 

 group of organisms characterized by a definite floristic com- 

 position, presenting uniformity in physiognomy and struc- 

 ture, and growing under uniform habitat conditions. (2) In 

 an abstract sense, a group of concrete communities or stands 

 that are classified together because they meet certain stand- 

 ards of similarity. See Association type, Index of similarity. 

 (3) In the Clements' sense, a Climatic climax (q. v.) unit 

 that includes all of the successional stages preceding or 

 associated with it. Plant association and animal association 

 emphasize populations of plants or animals respectively 

 within an area. 



Association, Coefficient of 



A measure of the frequency of occurrence together of 

 two species not due to chance, calculated by dividing the 

 number of samples in which both occur together by the 

 number of samples in which it is expected they would occur 

 by chance alone. 



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