of mammalian ecology, avian ecology, insect ecology, 

 parasitology, and so on. When emphasis is placed on 

 habitat, we speak of oceanography, the study of ma- 

 rine ecology; limnology, the study of fresh- water 

 ecology; terrestrial ecology, and so on. Animal eth- 

 ology is the interpretation of animal behavior under 

 natural conditions : often, detailed life history studies 

 of particular species are amassed. Sociology is really 

 the ecology and ethology of Mankind. 



Ecological concepts, which may be grouped to- 

 gether as applied ecology, have many practical appli- 

 cations ; notably wildlife management, range man- 

 agement, forestry, conservation, insect control, 

 epidemiology, animal husbandry, even agriculture. 



This preview of ecology indicates the great 

 breadth and unique character of the subject material 

 which justifies the view of ecology as one of the three 

 basic divisions of general biological philosophy. 



HISTORY 



That certain species of plants and animals 

 ordinarily occur together and are characteristic of 

 certain habitats has doubtless been common knowl- 

 edge since intelligent man first evolved. This knowl- 

 edge was essential to him for procuring food, avoid- 

 ing enemies, and finding shelter. However, it was not 

 until the fourth century bc, that Theophrastus, a 

 friend and associate of Aristotle, first described in- 

 terrelations between organisms and between organ- 

 isms and their environment. He has, therefore, been 

 called the first ecologist (Ramaley 1940). 



The modern concept that plants and animals occur 

 in closely integrated communities began with the 

 studies of August Grisebach, a German botanist, in 

 1838; K. Mobius, a Danish investigator of oyster 

 banks, in 1877; Stephen A. Forbes, an American, 

 who described the lake community as a microcosm in 

 1887; and J. E. B. Warming, a Danish botanist, who 

 emphasized the unity of plant communities in 1895 

 (see Kendeigh 1954 for further details and literature 

 citations). C. C. Adams recognized and described 

 many animal communities in his ecological surveys of 

 northern Michigan and of Isle Royale in Lake Su- 

 perior, published in 1906 and 1909. V. E. Shelford 

 presented a classic study of animal communities in 

 temperate America in 1913, and Charles Elton pub- 

 lished an outstanding analysis of community dy- 

 namics in 1927. Although an appreciation of the fact 

 that the whole community is one biotic unit, rather 

 than one unit of plants and another of animals, 

 may be discerned in the writings of some early in- 

 vestigators (eg., J. G. Cooper in 1859), the fact has 

 been brought to modern emphasis in the work of 

 F. E. Clements and V. E. Shelford, especially in their 

 Bio-ecology published in 1939. 



Succession of plant species after burns and in 

 bogs has been known in a general way since about 

 1685 ; and European ecologists have studied succes- 

 sion since the late nineteenth century. The present- 

 day interest in succession, however, especially in 

 North America, dates from the plant studies of 

 Henry C. Cowles in 1899 on the sand dunes at the 

 south end of Lake Michigan, and the work of Fred- 

 eric E. Clements, 1916. C. C. Adams and V. E. Shel- 

 ford, in the citations noted were among the first to 

 apply the concept to animals. 



Geographic ecology, in the modern sense, dates 

 from the generalizations on the world-wide distribu- 

 tion of animals made by the French naturalist, 

 Georges L. L. Buffon (lived 1707-1788), and the 

 explorations of the German botanist, Alexander von 

 Humboldt (lived 1769-1859). There was lively inter- 

 est and many important contributions in this general 

 field during the nineteenth century ; notably, the life- 

 zone concept of C. Hart Merriam (1890-1898) needs 

 special mention. During the present century the con- 

 cept of biotic provinces is identified with L. R. Dice 

 (1943) and the biome concept with F. E. Clements 

 and V. E. Shelford (1939). The broad survey of 

 ecological animal geography made by R. Hesse in 

 1924 exerted considerable effect and this treatise was 

 later translated into English and revised by W. C. 

 Alleeand Karl P. Schmidt (1951). 



The study of population dynamics, so important 

 in modern ecology, dates back at least to Malthus, who 

 pointed out in 1798 the limitation to population 

 growth exerted by available food. Darwin, in 1859, 

 recognized the importance of competition and preda- 

 tion in developing his theory of evolution. Pearl, 



1925, analyzed mathematically the characteristics of 

 population growth, and Lotka, 1925, and Volterra, 



1926, developed theoretical mathematical equations 

 to show the manner in which populations of different 

 species interact. These studies led to the classic ex- 

 periments of Gause, 1935, with interacting popula- 

 tions of predators and prey. Nicholson's publication 

 in 1933 stimulated much thinking concerning the fac- 

 tors that stabilize populations at particular levels. 

 Andrewartha and Birch, 1954, emphasized the im- 

 portance of climate and other factors on determining 

 the size of populations. 



The measurement and analysis of energy use by 

 organisms for existence and growth is now of very 

 great interest in ecology. Attention to biological pro- 

 ductivity began in the 1930's in connection with prac- 

 tical pond-fish culturing in Europe and the limnologi- 

 cal studies of Thienemann in Europe and of Birge 

 and Juday at the University of Wisconsin, but the 

 modern crystallization of the subject came with the 

 fresh-water and marine investigations of Lindeman, 

 Hutchinson, and Riley at Yale University (Ivlev 

 1945) and of Howard and Eugene Odum. An early 



Background 



