CHAPTER V 

 CLIMATIC FACTORS 



Studies of the structure of vegetation are likely to fail in thcii 

 object if not accompanied by a search for the underlying causes of 

 the social union and the mutual dependence of the component plants. 

 This research into the household economics of the community is the 

 function of synecology. 



The serious study of the problems of synecology is now at its very 

 beginning, because the chief interests of most ecologists have centered 

 in autecology, the life relations of the individual plant. Autecology 

 can be studied in gardens, plant houses, and laboratories, but the 

 problems of synecology must be investigated in the open, under natural 

 conditions. 



The impossibility of separating the various factors that are opera- 

 tive in nature greatly hampers these studies. Those investigators who 

 regard synecology as the foundation of phytosociologic classification 

 and, indeed, of the whole structure of plant sociology, must not forget 

 how insecure that foundation still is. Wholly new problems and 

 fundamental changes of viewpoint have come forward recently with 

 surprising suddenness, especially in the field of synecology. 



Synecology is inseparably bound to the concept of the plant com- 

 munity. The fathers of geobotany, Heer, Lecoq, Sendtner, and 

 Kerner, sought to understand the basic causes of the social relation 

 of certain plants. In Sendtner's classic " Vegetations verhaltnisse 

 Siidbayerns nach den Grundsatzen der Pflanzengeographie" (1854) not 

 less than 136 pages are devoted to the influence of climate and soil on 

 vegetation. Kerner's "Pflanzenleben der Donaulander" (1863) was 

 epoch making. In glowing terms it brought even to the layman an 

 understanding of the relation of the principal plant communities of 

 Austria-Hungary to the environment. 



The most important landmark in the development of synecology 

 since Heer was Warming's textbook of ecologic plant geography pub- 

 lished in 1895 in Danish, 1896 in German, 1909 in English. It is an 

 inexhaustible mine of trenchant observation and fertile suggestion. 

 Here for the first time the social life of plants was presented from the 

 standpoint of the influence of species upon one another. Attention was 

 also directed to the competition between species and communities. 



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