132 



FOREST COMMISSIONER S REPORT. 



Considerable observation of my own on this point is confirmed 

 by the experience of Mr. Pike and others. It may be summed 

 up in the rule that in ordinary stands of virgin spruce the 

 trees between six and twelve inches in diameter do not greatly 

 out-number those of larger size. This rule, I think, will hold 

 true not only on the Androscoggin, but on representative 

 stands of spruce everywhere. In connection with this matter, 

 I invite the attention of the reader to the record of sample 

 areas o-iven earlier in this work, which were not selected 

 with reference to this principle.* 



Spruce on the Grafton acre. 



Diameter. 



0) 



S a) 





a 



Over 18 inches 



15-18 



12-14 inclusive 

 10 and 11 



8 and 9 



6 and 7 



3-6 



Under 3 



6 

 24 

 10 

 12 

 24 

 21 

 63 

 366 



526 



500 

 1,200 

 290 

 225 

 265 

 120 

 125 

 35 



2,760 



1,800 



4,200 



1,160 



837 



795 



8,792 



Of full more general interest is the relation in regard to 

 volume and scale. Leaving out trees under eight inches, the 

 trees over fourteen inches in diameter on this acre comprise 



* Reason for this may be seen on considering the relative age of trees of these 

 different sizes. A six-inch tree in virgin growth like this is probably on the 

 average 100 to 125 years of age. Mr. Pike in several hundred trees examined by 

 him, found no eight-inch tree less than 125. The period of growth from six to 

 twelve inches (see rule for diameter growth in thinned timber on page 123) must 

 represent as much as seventy-live years. Trees pass the twelve-inch limit therefore, 

 at not far from 200 years of age. Now they seldom live— as was shown in the last 

 Maine Forest Commissioner's Report— to over 300. Therefore considering the 

 hardiness and fieedom from disease of spruce ordinarily, it seems reasonable 

 that the trees between 125 and 200 should about equal in number those from 200 

 to 300. 



Of course there are exceptions to this rule. There are thick growths of small 

 trees. There are areas of young timber, grown up probably on old fires or blow- 

 downs. I am speaking of the usual well grown stand only. 



