INTRODUCTION 31 



is a Stand of characteristic form. The form of a stand 

 has reference to the arrangement among the different tree- 

 classes. The form depends primarily on the distribution 

 of the age-classes. Trees of different ages may mingle 

 together proiniscuously; the age-classes may be in groups; 

 the trees ma\' be all of about the same age; or there 

 may be a more or less complete canopy of crowns, and 

 underneath this a separate story of smaller trees, whose 

 crowns form a secondary canopy. The forms most com- 

 monly recognized are the following: 



A. High Forest Forms. 



1. Selection Form. — Trees of different ages, from the 

 seedling to maturity, are represented, mingled individ- 

 ually or in small groups. 



2. Regular or Even-Aged Form. — The trees are ap- 

 proximately even-aged. The term is not confined to 

 stands in which the trees are exactly even-aged. If the 

 majority of the trees have nearly the same age and their 

 crowns form a clearly defined, regular canopy, the stand 

 is classed as regular. In a virgin forest a stand is regular 

 if the majority of the trees are of merchantable size. 



,1. Irregular Form. — Through unregulated cuttings or 

 accidental injuries the stand has been broken and there is 

 an irregular representation of two or more ages. The 

 age-classes are not all at hand, and therefore it is not of 

 the selection form. The irregular form necessarily varies 

 enormously. 



4. Two-Storied Form. — There are two distinct stands 



