Table 1 . - -Distribution of tree samples for specific gravity analysis 



D.b.h. : Crown class : 



(in.) : Dominant : Codominant : Intermediate : Suppressed : 



______________ Number - -- - — _________ 



4 





2 



2 



2 



6 



6 



2 



2 



4 



5 



13 



8 



1 



6 



8 



5 



20 



10 



1 



6 



3 



2 



12 



12 



4 



3 



4 





11 



14 



o 

 O 



4 



1 





lo 



16 



3 



4 



2 





9 



18 



■ 3 



3 







6 



20 



3 









3 



22 



3 



3 







6 



24 



2 









2 



26 



2 









2 



28 



2 









2 



30+ 



3 









3 



Total 



37 



33 



24 



14 



108 



Determination of core specific gravity . --Specific gravity at breast height was obtained 

 from cores taken with a standard increment borer . The cutting diameter of the borer was 

 calibrated by a taper gage periodically during the fieldwork. The average diameter was 0.171 

 inch. The length of the core from end of last growing season to the pith was measured to 

 ±0.01 inch immediately upon extraction. The last 20 annual rings were then severed and their 

 length recorded. The cores were inserted in numbered paper straws for transportation to the 

 laboratory. After drying for 25 hours at 105° C, the cores were weighed on a precision 

 balance . Specific gravity (grams of dry wood fiber per cubic centimeter of green volume) was 

 computed from the following formula: 



Sp.gr. = 0.0777 W/D^L 

 where W = ovendry weight (grams) 



D = diameter of increment borer (inches) 

 L = length of core (inches). 



The mean specific gravity of the cores to pith was 0.388 with a standard deviation of 

 ±0.030 per tree. The standard deviation of the separate cores about the mean for the tree was 

 ±0.022. Hence, the standard error of the mean of the two cores to pith for a single tree was 

 ±0.016. 



The mean specific gravity of the 20-year increment was 0.397 with a standard deviation 

 of ±0.048 per tree. The standard deviation of the four separate cores about the tree mean was 

 ±0.054. The mean of the four cores for the 20-year increment specific gravity thus has a 

 standard error of ±0 . 027 . 



3 



