the ungrazed prairie, was probably an important interaction. 



Attempts have been made to integrate the characteristics of 

 abundance and frequency in estimations and measurements; even 

 such terms as "sparse," "frequent," "abundant," and others, 

 usually include connotations of both dispersal and numerical 

 abundance or cover. Objective methods have been devised for in- 

 tegrating quantitative data on abundance and frequency," and 

 the frequency-abundance index has been used to advantage in 

 comparing the importance of one or more species in various 

 communities. ^°^ This is exemplified in the following table show- 

 ing ratings of five species in three communities in western North 

 Dakota, on the basis of 100 as the maximum (Figure 2-6). These 

 index figures were used as one of the chief criteria in classifying 

 36 stands into 9 community-types. 



The frequency-abundance index was also used effectively in 

 comparing a virgin grassland with two grazed grasslands in the 



Analytic CHaaracteristics of tHe Community • 115 



