Reconnaissance Data and Marking Timber 461 



ideal acre, therefore, represents the maximum amount of crowns 

 that can be crowded on one acre and still have each tree enjoy 

 the maximum of direct sunlight. There is, undoubtedly, under 

 normal conditions considerable overtopping, and for this rea- 

 son the ideal acre on the basis of total crown space is conserva- 

 tive, for it does not take this into account. On the basis of the 

 ideal acre 84 per cent of our Yellow pine stands have a crown 

 density of less than 0.42 or are less than half stocked. 



Such a basis of comparison as the one above is fairly indica- 

 tive of the degree of density of the Yellow pine stands. There 

 is a relative comparison between our poorest and best stands, 

 if nothing else. It is safe to say that the ideal is by no means 

 the best that can be grown, for reasons mentioned above. For 

 this reason these densities are probably high. 



The Representation of Age Classes 

 By consulting the latest growth tables on Yellow pine, the 

 following relation appears to exist between the diameter groups 

 mentioned above and the age of the trees: 



Diameter Group Age 



6-10 inches 40-55 years 



11-20 55-100 



21-30 100-150 



31-40 150-270 



Over 40 Over 270 



For the purposes of this study only three age classes will be 

 considered, as follows : 



TABLE 5 



The following table gives for each crown density class the 

 representation of the three age classes in per cent : 



TABLE 6 



Trees 



Crown Per Acre 



Density All Ages 



Class From Table 



Very open I 6.8 



Open II 14.4 



Medium Ill 17.9 



Dense IV 26.1 



Very dense V 39 . 7 



Average 14. 8 



Maximum Acre 80. 



