Stem Analyses. 163 



It must be remembered that the object of stem analyses is 

 to secure figures of volume growth for a given species which will 

 enable us, after compiling a large number of values and averag- 

 ing them together, to construct a table showing the average in- 

 crease in volume by decades. That is, it is desired to know what 

 the volume of White Pine, or any other species, will 

 be, under average conditions, at an age of 10 years, and 

 again at 20 years, 30 years, 40 years, etc. Since the age at 

 the stump (cross-section i) is always slightly less than the true 

 age of the tree, (from 2 to 10 years, often, depending on the 

 stump-height, and the rate of growth of the seedling of the 

 species), and a number of years, — usually determined by a study 

 of seedlings — has to be added arbitrarily to secure the total age 

 of the tree, it is suggested that these years be added before the 

 stem analysis is recorded, instead of afterward, thereby making 

 it possible to secure results which can ultimately be averaged to- 

 gether with a smaller degree of error. For example, it is known 

 that White Pine seedlings attain an average height of one foot 

 at an age of 5 years ; a height of 2| feet at an age of 6 years, 

 etc. (*) ; if the stump of the White Pine being analysed is one 

 foot high, it is then determined that 5 years must be added to the 

 age of the stump to secure the total age of the tree, which is 

 entered on the blank form at ("k"), the space provided for it. 



Now, as each section is analysed, the rings are counted back- 

 ward from the bark to the center, beginning at the outside and 

 designating the outermost ring with its proper number, viz., the 

 total age of the tree, and not the number of rings which happen 

 to be found on that section. Thus, if the total number of rings 

 at the stump is 80, and 5 years are to be added for a stump one 

 foot high, then the outermost ring on the stump will be counted 

 "85" and the next one inside "84", etc., counting backward, and 

 placing a mark at the even decades, 80, 70, 60, 50, etc. In like 

 manner, the outermost ring on all subsequent sections will be 

 called "85," and the counting proceed backward, until the center 

 is reached, marking each decade as before. t 



* Values are taken from U. S. Forest Bulletin 22, "The White Pine," by 

 V. M. Spalding and B. E. Fernow, page 28. 



flf it is preferred by some to count from the center outward, the num- 

 ber of rings on the section can be subtracted from the total age, and the 

 counting begun at tJie age obtained. For example, on section 5 there are 

 38 annual rings ; this subtracted from 85 = 47, and the counting may begin 



