APPENDIX. 



195 



Table 64.— Birch, Paper— Yield Per Acre— Pure (100 Per Cent) 

 Birch Stands. 



PENOBSCOT, PISCATAQUIS, SOMERSET, AND FRANKLIN 

 COUNTIES, ME. 



[Data gathered by R. L. Marston for Paper Birch Study, 1903-1907.) 





Quality I. 



Quality II. 









S^ 









^^ 





4^ 









0) 











c3x3 







•^ Qj a> 



c3X3 







■^ o.2^ 



Age. 













i 





o p,^ 









'6 

 '3 



ip 



W)o3 



-=5 











<v 





VH >^ 









«" >«« 







tc 



% 



o o o 







'>> 



O O o 





> 



C3 



a; 

 > 



o 



SflS) 





> 



'c3 



o 



III 





< 



< 



^ 



.^C3C3 



<*1 



< 



Eh 



>^ 



Y'ears. 



Inches. 



Feet. 



Cu.ft. 



Per ct. 



Inches. 



Feet. 



Cu.ft. 



Per ct. 



15 



2.3 



24 



710 







1.8 



21 



410 







20 



3.4 



33 



1,020 



4 



2.6 



28 



580 







25 



4.5 



41 



1,340 



27 



3.4 



34 



770 



18 



30 



5.6 



48 



1,700 



46 



4.3 



40 



1, 010 



35 



35 



6.4 



.54 



2,090 



63 



5.0 



45 



1,290 



50 



40 



7.2 



58 



2,520 



75 



5.7 



49 



1,580 



63 



45 



7.8 



62 



2,950 



85 



6.3 



53 



1,890 



73 



50 



8.4 



65 



3,340 



91 



6.8 



56 



2,220 



82 



55 



8.8 



68 



3,660 



96 



7.2 



59 



2,530 



89 



60 



9.2 



70 



3,940 



98 



7.6 



61 



2,810 



94 



65 



9.6 



72 



4,190 



100 



7.9 



64 



3,060 



97 



70 



10.0 



74 



4,450 



100 



8.2 



66 



3.300 



100 



Note.— These sample plots were taken in unmanaged stands. All plots with a 

 density less than 50 per cent were discarded. All plots containing less than 40 per 

 cent birch were discarded and the remainder reduced to 100 per cent birch by 

 dividing the actual birch yield by the percentages of the total basal area formed by 

 the birch. Hence the table applies only to pure birch stands of average density 

 (quality 1, 83 per cent and quality II, 75 per cent). For the yield of a mixed stand, 

 containing, for example, 60 per cent of birch, a corresponding reduction would be 

 made in the yield. The number of trees per acre was exceedingly irregular and 

 was therefore excluded from the table. 



The volume given is total stem volume, though the lowest measurement taken 

 in the sample trees was at 4.5 feet, and this disregard for butt swelling makes the 

 yield conservative. 



Based on 20 quality I and 26 quality II, sample plots. 



