THE SUBJECT MATTER OF ECOLOGY 15 



broad training in this field is a necessity. Soils are a constant con- 

 cern of the ecologist both as to their origin and development and 

 as to the paralleling vegetational characteristics as modified by 

 water, aeration, and nutrition. The frequent recurrence of prob- 

 lems related to climatology suggests its desirability, and the in- 

 creasing use of quantitative methods requires an appreciation of, if 

 not actual facility in, the use of statistical methods and experi- 

 mental design. Also, ecological problems frequently overlap those 

 of applied fields such as agriculture, forestry, and range manage- 

 ment. In addition to the terrestrial ecology with which we shall 

 primarily concern ourselves in this text, there are the special fields 

 of limnology, dealing with fresh-water environments, and marine 

 ecology and oceanography with all their particular problems. 



These suggestions are indicative of the diversity of subject mat- 

 ter included in ecology. Specialization is a natural and desirable 

 result so long as it contributes to the ultimate goal of understand- 

 ing the interrelationships of organisms and environment and to 

 clarifying the natural laws under which the complex operates. 



HISTORICAL DEVELOPMENT OF PLANT ECOLOGY 



The origins of modern plant ecology are, of necessity, diverse. 

 Designation of the limits and ranges of species by Linnaeus and 

 other early systematic botanists led to the development of floris- 

 tic plant geography, which considers the origin and spread of 

 species. The next step was in the direction of explaining distribution 

 of species. Humboldt, a taxonomist who was a great traveler, was 

 impressed by the correlations with climate that he observed. As a 

 result, he developed his ideas so effectively at the beginning of 

 the nineteenth century 126 that the influence of his thinking is 

 still apparent in the interpretations of climatic plant geography. 

 Schouw, 214 one of Humboldt's students, was the first to attempt 

 the formulation of laws regarding the effectiveness of light, mois- 

 ture, and temperature in species distribution. Somewhat later 

 (1855), still another taxonomist, A. de Candolle, published studies 

 along this line but with major emphasis upon temperature as a 

 controlling factor. Attempts to correlate vegetational distribution 

 with single factors continued for several years and culminated in 

 Merriam's 173 study of temperature zones for all of North America. 



