Timber Sales in Selection Forests 95 



Recording the data. If only the amount of timber which is 

 to be sold is desired, the diameters of only the merchantable 

 trees by species are recorded or, if preferred, their contents may 

 be estimated in merchantable logs. If the total stand is to be 

 estimated only to any diameter limit, they may be recorded as 

 above. 



But to make a complete analysis of the stand as is required 

 by the Forest Service previous to making a sale, more detail 

 is required. Whether we later use the data, practically no more 

 work is required to record separately the trees which should be 

 removed and those which should be cut for cultural reasons. 

 Should we regulate the cutting solely with the view of working 

 towards definite normality, separate columns for the trees "to 

 leave" and "to cut" need not be kept. If they are to be kept 

 separate, one should have pretty well defined ideas from the 

 start regarding the diameter limit, even if he takes some time 

 to consider the matter. 



The diameters of trees under 15 or 16 inches can, with prac- 

 tice, be estimated; but for larger diameters it is safer to use 

 calipers or the "Biltmore Stick." The measurement of the height 

 of an occasional tree may be taken with the assistance of the 

 clinometer or otherwise, if you have a volume table based on 

 diameters and heights, in order that more accuracy may be had 

 in applying the volume table. The estimated quality of locality 

 may also assist in choosing the volume in such a volume table. 



Working up Stock Data. 



For a concrete example we will suppose that after covering 

 the sale area we have recorded 20 quarter acre plots. 



By species and separately for the trees to be left and for 

 those to be cut we would next proceed to find the total number 

 of trees in each diameter class on the 20 plots aggregating 5 acres. 

 By dividing these sums by 5 we find the number of trees in each . 

 diameter class for each species on the average acre. Next we 

 find the total basal area of two or more diameter groups i. e., the 

 total area in square feet of the tops of stumps that would result 

 if all the trees were cut smoothly off with a saw at breast height. 

 Then, by dividing this total basal area in each group by the total 

 number of trees in the group we obtain the basal area of the 

 average tree of each group. Finally the diameter of a circle of 

 that area is computed or found in a table of areas of circles such 



