As a result of items 3 and 4, a new weighted regression was computed, this time 

 with an intercept. The resulting intercepts were small [0.03 ft^ (0.0008 m^) for both 

 pinyon and juniper], and the slope corrections were not unreasonable. A plot of the 

 weighted residuals about the models with intercepts revealed that items 1 and 2 had 

 been unchanged, items 3 and 4 had been corrected, and item 5 for juniper had been im- 

 proved. Therefore, the weighted models with intercept values were accepted as the best 

 linear unbiased estimators of cubic volume. 



RESULTS 



The final equations which follow have the following use restrictions: 



1. The minimum top diameter limits must be in the range of 1 to 7 in (2.5 to 

 17.8 cm). 



2. The number of stems cannot exceed 20. 



3. The cubic volume predicted is total volume from ground line to point of 

 minimum top diameter including bark and limbs. 



4. The equations are considered representative of pinyon, Utah juniper, and Rocky 

 Mountain juniper in northern New Mexico. Use elsewhere should be accompanied by suit- 

 able checks of applicability. 



The pinyon cubic volume equation is: 



F = c + b/^E 



where : 



a (English units) = 0.02768 



c (metric units) = 0.0007838 



X (English units) ^ D - W 

 D - TD 



X (metric units) = 



2.54 



D = basal diameter (at ground line) in inches for English units or centimeters 

 for metric units 



H = total tree height in feet for English units or meters for metric units 



TD = minimum top diameter limit in inches for English units or centimeters 

 for metric units 



b (English units) = 0.08789 - 0.03675(11.0 - TD)^-'^^ 



b (metric units ) = 0.0081652 - 0.0024637(27.94 - 70)0.35 



n (English units) = 1.1 + 0.007(11.0 - TD)'^-^ 



n (metric units) = 1.1 + 0.001085(27.94 - TO)^-^ 



F = gross cubic volume outside bark to the specified minimum top diameter 



limit including stump and limbs in cubic feet for English units or cubic 

 meters for metric units. 



5 



