NOTES ON A METHOD OF STUDYING CURRENT 

 GROWTH PERCENT 



By B. a. Chandler^ 



During the last two years the writer has had occasion to predict 

 the ciirrent growth of several uneven-aged stands that have been 

 lumbered under market conditions which permitted various degrees 

 of utilization. The first really satisfactory results were obtained 

 by using the following method: the diameter for the last 5 and 

 10 years for each d.b.h. class was determined and a curve produced 

 through these points for the next 10-year period.^ 



The details of the method differ slightly from that described 

 by Mr. Stetson.* Plots were not used because our growth studies 

 were made in connection with valuation survey estimates. To 

 determine growth for the whole stand, rates of growth were deter- 

 mined for each diameter class and these were applied to the 

 volumes of the corresponding diameter classes, as shown in the 

 stand table. No special study of height growth was made; the 

 height curve made for these estimates, representing the height of 

 the whole stand, was used to predict height growth. Therefore, 

 the trees which were bored to get the growth for the last 5- and 

 10-year periods were scattered over the whole stand and were 

 selected in practically the same way that the trees for the height 

 curve were selected. The second change consisted in plotting 

 the current growth figures on the basis of d.b.h. in order to even 

 off the irregularities between trees of different but consecutive 

 diameters. Diameters were plotted on the abscissae and radial 

 growth on the ordinates (Fig. 1). The points so plotted were 

 evened off by a curve which showed the relation of current growth 

 to diameter. As growth was measured separately for the 5- and 

 10-year periods, separati curves were made. It should be noted 

 that it was the total growth for each period that was used for this 

 set of curves, and not the average growth for each 5-year period. 



In taking the field data it will always be necesary to classify 

 the trees in groups of some kind. The character of the classifica- 



' Assistant State Forester, Vermont. 



* Forestry Quarterly, Vol. VIII. Page 326. Suggestions on Predicting 

 Growth, by J. G. Stetson. This method was devised by Prof. H. H. Chap- 

 man in 1909. 



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