8GG JOURNAL OF FORKSTRY 



eter growth measurements are not now required for volume calcula- 

 tions, the stump growth may be determined in the direct and simple 

 way. The rings are counted from the pith outward, the growth by 

 decades averaged arithmetically, and a single row of points plotted. 

 When the rings are counted toward the center, the measurements can- 

 not be averaged arithmetically. A d. b. h. growth curve is then con- 

 structed from the stump curve in the standard way. The construction 

 of a height growth curve is carried out in the usual way. The most 

 radical change, however, as well as the most substantial reduction in 

 the quantity of work, is in connection with the construction of a vol- 

 ume-growth curve. The d. b. h. and height-growth curves are applied 

 to the volume table and the volume at each decade is secured without 

 any detailed computations. 



Thus all the relationships ordinarily worked out when the standard 

 method of complete stem analysis is followed are worked out by this 

 method, with an expenditure of but half the labor involved in the other. 

 The main objections seem obvious and it is not desired to hide or over- 

 look them. They relate entirely to the method of computing the vol- 

 ume growth, as there is no basic change in the method of establishing 

 the other relationships. The method of computing volume growth by 

 applying to the volume table data read from the diameter and height 

 growth curves means that any errors arising from the incorrect draw- 

 ing of those curves will be carried on to the volume-growth curve and 

 perhaps be distorted there. Each of the curves, however, is constructed 

 by averaging the data arithmetically and plotting only a single row of 

 points. It is found that in most cases the final curves will follow 

 closely these points and the chance of distortion is small. It should be 

 borne in mind, too, that the volume table is based entirely on the same 

 trees that constitute the basis for the diameter and height growth 

 curves. 



Another objection that may validly be made to this method is that 

 it does not take sufficient account of the change in form of the indi- 

 vidual trees during the various periods of their growth. Since in the 

 volume table the small sizes are most often represented by the smaller 

 suppressed trees of the present stand, the data taken from the volume 

 table may not give the correct volume growth at the earlier ages. This 

 would be overcome to a large extent if the study could be carried out 

 in young stands as well as in old; but this cannot usually be done if a 

 logging operation is being followed. 



For the same reason this method may not be well adapted to a study 

 of volume growth in cubic feet, unless the interest centers mainly in 

 merchantable sizes, as would be the case where the object of the study 



