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.] 



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 11,75 percent). 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. 



