HISTORICAL DEVELOPMENT OF THE CONCEPT 11 



BIOTIC RESEARCHES 

 The Biotic Formation on Land 



Vorhies and Taylor (1922) ; Taylor and Loftfield (1924) ; Greene 

 and Reynard (1932). Vorhies and Taylor made a study of the kan- 

 garoo rat in relation to vegetation which brought out various biotic 

 interactions. Taylor and Loftfield determined the amount of forage 

 taken by the Zuni prairie dog, while Greene and Reynard showed the 

 benefits of some rodent reactions to the soil. 



These studies were a part of a project in grazing research which 

 was organized jointly by the Carnegie Institution, the U. S. Biological 

 Survey, the U. S. Forest Service, and the University of Arizona (cf. 

 Year Books 16-30, Carnegie Institution of Washington, 1917-1931). 



Palmgren (1928, 1930). In connection with the investigation of 

 the bird life in the forests of southern Finland, Palmgren has dis- 

 cussed the ecological synthesis of plant and animal groups and has 

 recognized that vegetation must form the basis for this. He also 

 subscribes to the principles that animals must be treated as members 

 of the community and that green plants assume the primary role in 

 the latter, with the important corollary that the ecological study of 

 animals must rest in the first instance upon their intimate relations 

 with plants. He has employed the forest types of Cajander and the 

 line surveys of Ilvessalo as the ground plan for his work, which has 

 dealt especially with the numbers and characteristic species of birds. 

 Although he uses the term bird society or association {V og elver ein), 

 it appears evident that he does not intend to set these apart from 

 the biotic community. 



He finds that the best forest types (Sanicula and Oxalis-Myrtillus) 

 show clearly the influence of the tree species upon the quantitative 

 expression of the bird fauna inasmuch as the numbers are significantly 

 larger in deciduous woods. It appears, however, that the herbaceous 

 layers take the leading role in this and that the nature of the stand 

 of trees comes next- In this connection, his comparisons between 

 deciduous, mixed, and coniferous forests are supported by the rela- 

 tions to be found in North American woods. He gives summaries of 

 bird density for eight different forest types and lists the character 

 species and their abundance for the seven biotopes considered. His 

 methods and results represent the most extensive quantitative attack 

 upon the problem of the role of birds in the biotic community and 

 with the addition of the dynamic outlook will serve as the model for 

 other climaxes. 



Weese, 1924; Blake, 1926, 1931; Smith, 1925, Smith-Davidson, 

 1930, 1931. These authors made a series of studies in a forest in cen- 

 tral Illinois composed chiefly of red oak, maple and elm. The work 

 of Weese and the succeeding investigators was essentially quantitative. 

 Weese devoted considerable attention to experiments designed to 

 reveal the factors controlling the position of the prevalents in the 

 layers of the forest; he discussed seasonal communities and described 

 winter movements of invertebrates. Blake (1926) carried on an inves- 



