DETERMINATION OF AREAS FROM DENSITY FACTOR 417 



density by classes, yet the total error is probably very small. The 

 method is as follows: 



The standard density, or 100 per cent, as expressed in the yield 

 table, calls for a definite volume per acre, differing with each age. 



The total volume and age of each age class in the forest are known. 



By dividing this volume by the standard volume on 1 acre of the 

 required age from the yield table, the area which would be required by 

 the age class if stocked at 100 per cent density is found. 



The sum of the areas found in this manner for all the age classes 

 would be the total area of the forest if the density of stocking were 

 100 per cent. 



Since the total area actually stocked is known for this sum or total 

 of age classes, but not for each age class separately, it follows that, 

 Actual per cent of density for total area 



/Area 100 per cent stocked\ 

 \ Total area / 



and, assuming this per cent for each class, 



. , / Area 100 per cent \ 



Area in each age class = I , , , . , I 



100 



\stocked in age class/ per cent of density' 



ILLUSTRATION 

 Second-growth Hahdwoods in Central New England 



Actual area 624 acres. 



416 

 Density per cent 7rr = 66| which will be assumed to apply to each of the four 

 624 



age classes represented. 



To determine the area in each age class; 



100 

 Ratio to fully stocked area — = 1.6. 



oof 



