306 



JOURNAL OF FORESTRY 



The following facts may be noted from the diameter growth curves : 



1. At a period five decades back from the time of cutting all age 

 classes began an accelerated growth. 



2. The largest — that is, the oldest — age class at that time was 3.8 

 inches on the stump. 



3. The younger trees responded more quickly and grew more rapidly 

 than the older. 



4. The youngest age class passed through no period of suppression, 

 and was cut for pulp 56 years after it passed the stump height. 



5. All age classes show a crowding in the last decade. 



Comparisons of the results shown in Table 2 serve to emphasize the 

 comparatively equal development of stem in all age classes and show 

 a larger number of trees in the 60-70 year class than in any other. 



The average age of all the trees 50 years ago was 27 years, and the 

 average diameter on the stump for that age 2.16 inches. The average 

 diameter of all trees at the time of cutting was 11. 16 inches on the 

 stump, and the average age at that time "jy years. 



No complete caliper record was obtained, since the true significance 

 of the stand was not known at the time the measurements were made. 

 It is still possible to obtain such a record from the stumps, and so obtain 

 yield and an idea of the condition of the cut-over area. 



This study is sufficient basis for the assertion that a crop of balsam 

 fir, merchantable in the present interpretation of the word, can be pro- 

 duced in 60 years from seedlings. It must be pointed out also that 

 the stand does not show crowding until the last decade, and for this 

 reason would not need thinning during this period of production. No 

 statement can now be made as to the probable loss of trees from the 

 stand during the last 50 years' growth. 



T.A.BLE I. — Dimensions of 208 Trees {Balsam Fir) not Averaged by a Curve 



Diameter breast height outside bark, 

 inches.' 



Total height, 

 feet. 



9.63 I 62.7 



9-75 63 



10.2 I 04 



9.85 I 64 



10.4 I 64 



9.8 ' 64 



Average age, 



years, above 



the stump. 



56 



68 

 76 

 87 

 96 

 106 



Volume 



in cubic feet, 



total. 



15.84 

 16.30 

 17.96 

 16.90 

 18.60 

 16.70 



^ Bark thickness was taken as .6 inch from U. S. Dept. Agr. Bui. 55. 

 was interpolated from volume table 19, in same bulletin. 



Volume 



