34 



THE HISTORY OF ECOLOGY 



THE COMMUNITY CONCEPT 



Recognition of the existence of com- 

 munities of living organisms in nature is 

 not new. As shown earlier in this chapter, 

 the idea dates back to the classical Greeks. 

 In the modern period, according to Braun- 

 Blanquet (1932), Heer (1835), Lecoq 

 (1854), Sendtner (1854), and Kerner 

 (1863), all sought to understand the basic 

 causes of the interrelations of certain 

 plants, and Kerner "brought even to the 

 laymen an understanding of the principal 

 plant communities of Austria-Hungary to 

 the environment." 



Clements (1905) traced recognition of 

 the plant formation to Grisebach (1838), 

 who recognized it as the fundamental fea- 

 ture of vegetation. Earlier writers, Cle- 

 ments continues, "notably Linne (1737, 

 1751), Biberg (1749), and Hedenberg 

 (1754), had perceived this relation more 

 or less clearly, but failed to reduce it to a 

 definite guiding principle." Clements adds 

 that the acceptance of the "formation" as 

 a unit of vegetation took place slowly, but 

 this point of view came to be more and 

 more prevalent as a result of the work of 

 Kerner (1863), and a half-dozen others, in- 

 cluding Warming (1889)." Clements and 

 Shelf ord (1939) state that "the idea of the 

 plant community in general extends back- 

 ward for nearly two centuries," and, as re- 

 gards the biotic community, "Post (1868) 

 recognized that the organic world should 

 be dealt with in its entirety, but seems to 

 have had no definite idea of the community 

 as a unit." 



Darwin's recognition of the web of life 

 concept has akeady been mentioned. His 

 famous illustration of the relationship be- 

 tween the number of cats and the amount 

 of clover seed in an English community 

 illustrates his understanding of possible in- 

 tracommunity relationships. Saint-Hilaire 

 (1859) foreshadowed the concept, and 

 Haeckel (1869), in his classical definition 

 of "Oecology," also vaguely recognized the 

 existence of communities. 



Edward Forbes (1843-1844), in study- 

 ing the animal distribution in British wa- 

 ters and the Aegean Sea, discovered "prov- 

 inces of Depth" which "are distinguished 



• Warming's bibliography in the 1909 edi- 

 tion of his Oecology of Plants does not list a 

 title for 1889 among his thirteen publications 

 between 1869 and 1894, inclusive. 



from each other by the associations of 

 the species they severally include. Cer- 

 tain species in each are found in no other; 

 several are found in one region which do 

 not range into the next above, whilst they 

 extend to that below, or vice versa. Certain 

 species have their maximum of develop- 

 ment in each zone, being most prolific in 

 individuals in that zone in which is their 

 maximum, and of which they may be re- 

 garded as especially characteristic. Mingled 

 with the true natives of every zone are 

 stragglers, owing their presence to the sec- 

 ondary influences which modify distribu- 

 tion." 



Forbes clearly recognized the dynamic 

 aspect of the interrelations between organ- 

 isms and their environment. He stated liis 

 conclusions as follows (1843, p. 173): 



"The eight regions in depth are the bcene 

 of incessant change. The death of the indi- 

 viduals of the several species inhabiting them, 

 the continual accession, deposition and some- 

 times washing away of sediment and coarser 

 deposits, the action of the secondary influences 

 and the changes of elevation which appear to 

 be periodically taking place in the eastern 

 Mediterranean, are ever modifying their char- 

 acter. As each region shallows or deepens, its 

 animal inhabitants must vary in specific asso- 

 ciations, for the depression which may cause 

 one species to dwindle and die will cause 

 another to multiply. The animals themselves, 

 too, by their over-multiplication, appear to be 

 the cause of their own specific destruction. As 

 the influence of the nature of the sea-bottom 

 determines in a great measiure the species pres- 

 ent on that bottom, the multiplication of 

 individuals dependent on the rapid reproduc- 

 tion of successive generations of MoUusca, etc., 

 will of itself change the ground and render it 

 unfit for the continuation of life in that lo- 

 cality until a new layer of sedimentary matter, 

 uncharged with living organic contents, depos- 

 ited on the bed formed by the exuviae of the 

 exhausted species, forms a fresh soil for simi- 

 lar or other animals to thrive, attain their 

 maximum, and from the same cause die oflF." 



This is an early, perhaps the first, state- 

 ment of ecological dynamics, a subject much 

 emphasized in recent decades (see p. 563). 

 Elsewhere, Forbes (1844) regarded self- 

 produced, local destruction of a species as 

 a kind of "rotation of crops" and shows 

 clearly that he was more concerned with 

 the alternation of fossihferous and nonfos- 

 siHferous geological strata than with the 

 processes that we now know are connected 



