56 THE STUDY OF PLANT COMMUNITIES * Chapter I V 



approaches, which led to somewhat different conclusions. Several 

 centers of thought and research naturally grew up, which still in- 

 fluence our thinking and procedure. The ideas of the so-called 

 Zurich-Montpellier school have gained rather wide favor, largely 

 through the influence of Dr. J. Braun-Blanquet, 34 and they will be 

 summarized in the remaining section of the chapter. 42 



Before proceeding with this summary, it seems entirely appro- 

 priate to point out the unfortunate fact that Americans have been 

 slow to adopt the phytosociological approach, probably because 

 of a lack of appreciation of the usefulness of sociological data. Al- 

 though phytosociology is, in itself, only a phase of ecology, its 

 methods are useful far beyond the field for which they were de- 

 veloped. Whenever communities must be described or the sig- 

 nificance of individual species in a community must be evaluated, 

 phytosociological concepts and methods are applicable and usu- 

 ally with distinct advantages. This means that the methods are 

 useful in experimental studies of communities, for comparing one 

 community with another, for showing changes in a community 

 from year to year, and, in fact, whenever precise information is 

 needed about community structure and the part contributed by 

 various species. Its possible applications are almost unlimited. To 

 illustrate, various of its methods have been used to advantage in 

 such diverse problems as correlating the progressive changes of 

 vegetation and soil on abandoned fields, 20 showing the effects of 

 different intensities of fire on the structure of pine stands, 1S4 and 

 for demonstrating differences in virgin forest with changes of 



topography. 187 



STRUCTURAL CHARACTERISTICS 



The sociological characters of an individual stand or concrete 



o 



community may be conveniently grouped in two categories : 

 quantitative and qualitative. Quantitative characters, obtained by 

 quadrat methods, indicate numbers of individuals, their sizes, and 

 the space they occupy. Qualitative characters indicate how species 

 are grouped or distributed, or describe stratification, periodicity, 

 and similar conditions, and are based upon the knowledge derived 

 from long familiarity and observation of the community. 



Quantitative Characters. — Numbers of Individuals. — Under 

 some circumstances, it mav not be practicable to make actual 



