232 THE STUDY OF PLANT COMMUNITIES • Chapter IX 



Frequency in Percent 



llyrs 22yrs 3 I y r s 3 4 yrj 42yrs 75yr$ 110 yrj Oak - 



90 i i Hickory 



B Oak and Hickory Trees 

 \/////A Oak and Hickory Reproduction 

 [XX^ Pme Trees 



Pme Reproduction 



25- 



20- 



* 15- 



I 10- 



5- 

 0. 



35 



95 



100 



290 

 295 



300 



10 



Frequency in Percent 



Fig. 110. Relationships of trees and reproduction of pine and oak-hickory 

 in old-field succession in North Carolina as shown by their density and fre- 

 quency in successive ages of pine dominance leading to oak-hickory climax. 

 Frequency is indicated by width of columns, density by height. Such phyto- 

 sociological representations clarify relationships that might otherwise go un- 

 recognized. 



It is often possible for honest observation to be wrong, and only 

 quantitative and qualitative data will demonstrate the discrepancies. 

 Again, such data may bring to light pertinent information that 

 could not be realized by observation alone. When questions of 

 "why" "when" or "how" come up, they can be most satisfactorily 

 answered with absolute data. 



These things were soon realized by some early students of suc- 

 cession, and quadrat methods were introduced as a part of their 

 procedure. Early methods of sampling, however, were rarely ade- 



