DEVELOPMENT OF ASSOCIATION AND CLIMAX CONCEPTS 333 



term associes for developmental units and retained association only for climax 

 units. Even with this restriction, we must realize that all climax units are not 

 equivalent, that there are different kinds of climaxes, chief of which are 

 physiographic climaxes and regional climaxes. 



Shall the term association be used only for regional climax communities or 

 for all sorts of climax communities, physiographic and regional? Shall it be 

 thus restricted, or shall it be used for all relatively stable communities even 

 though developmental? Or shall the term be restricted to the abstract? The 

 local worker usually shuns the restricted usage and prefers to designate all 

 well-marked communities as associations. (I am not here concerned with 

 division of associations or associes into consociations, consocies, etc.) Exten- 

 sive work is sure to modify this view, for the great regional associations are 

 not comparable to the local associations. If association is to be used for all, 

 then the regional should be called major associations. In fact, such emphasis 

 is often desirable even when a broad association concept is used. 



The validity of an association concept (and of other community units) 

 has been questioned (Whittaker, 1951). I believe everyone will agree that 

 communities are recognizable in the field, that we do see patches of forest 

 to which we can give names, because of dominants. The objection is based 

 on the fact that communities do not have definite limits, but intergrade with 

 one another; that the species which seem to characterize them extend into 

 other communities, although probably in different proportions; that no two 

 communities are exactly alike; that vegetation (barring abrupt site differ- 

 ences) is continuous though differing from place to place. 



The climax concept, too, is questioned, perhaps because of rigidity of in- 

 terpretation in some schools of thought (Whittaker, 1953). The monoclimax 

 and polyclimax ideas do not help. To me, a monoclimax concept appears im- 

 possible (although I have been surprised to find that I am by some con- 

 sidered a supporter of the idea) ; equally, a polyclimax concept seems ques- 

 tionable. I adhere to the idea that there is more than one kind of climax. I 

 do not refer to the complex Clementsian units — as serclimax, disclimax, post- 

 climax, etc. — which I prefer not to recognize. Extensive investigation reveals 

 the recurrence, on mesic although not exactly similar sites, of climax com- 

 munities closely similar through wide geographic areas. Intensive or local 

 studies usually reveal the existence of other climaxes, stable communities re- 

 lated to other, sometimes extreme, sites. The first group of communities are 

 representative of what I prefer to call the regional climax — an abstract con- 

 cept. The second are physiographic climaxes, or, if you prefer, topographic, 

 or edaphic, climaxes. This should not be understood to imply that regional 

 climaxes are not influenced by topography — environment operates on all. Re- 

 gional climaxes are commonly, but not always correctly, referred to as cli- 

 matic climaxes. The relative prominence of these climax groups and of the 

 developmental communities in any region depends upon the age of the region 



