90 



FOREST COMMISSIONER S REPORT. 



GROWTH. 



Paper birch is commonly considered a very rapid grower. 

 To some extent this reputation is deserved, though the tree's 

 growth throughout Hfe is not so rapid as is often supposed. 

 It makes a quick start in early youth and shoots up more 

 quickly than most of the species with which it grows, and in 

 this way attracts attention. After the first five or ten years it 

 also makes a good diameter growth, but the rate begins to fall 

 off when the tree is about 30 years old, and gradually decreases 

 until in old age it is almost negligible. Perhaps another reason 

 for the prevalent notion that paper birch is such a rapid grower 

 is the fact that much smaller specimens can be utilized than with 

 other trees lumbered in the region, such as spruce, pine, balsam, 

 and hemlock. 



In any consideration of growth a distinction must be made 

 between seedlings and spourts, and the locality must also be 

 taken into consideration. Table i shows the growth of both 

 seedlings and sprouts in height and in diameter, while Table 2 

 shows their volume growth. The figures for the seedlings are 

 based on 50 full stem analyses of trees growing in low, rocky 

 ground near the shore of Hardy Pond in Piscataquis County, 

 Me. Those for the sprouts are based on 30 full stem analyses 

 of trees growing on a very rocky, rather thin-soiled hillside in 

 Carroll County. X. H. Both localities are of the second quality 



Table i. — Height and diameter groziih of paper birch. 



Age. 



Years. 



5 



10 



15 



20 

 25 

 30 

 35 

 ■10 

 45 

 50 

 55 

 60 

 65 

 70 

 75 

 80 

 85 

 90 



Height. 



Seedlings. 



Sprouts. 



Diameter breast- 

 high. 



Seedlings. 



Fret. 



13 



22 

 30 

 37 

 44 

 49 

 .54 

 58 

 62 

 65 

 68 

 71 

 74 

 76 

 78 

 80 

 HI 



Sprouts. 



