ACCRETION OF A FELLED TREE. 143 
their respective cross-sectional areas at that point by the length 
of the topless trunk. 
A more careful stem analysis of a tree affords detailed meas- 
urements from which the volume at any time during its lifetime 
may be determined very accurately. The following table of 
measurements of a pine will furnish data for the calculation of 
its volume at different ages, and its progressive development is 
graphically illustrated in Figure 38: 
‘S 4 “ Accretion in inches during past 
+g Sy ~ | eT ae eee 7 Sapa ee 
a gro | aid | 1 ; . 
ee | BG | BS |} Age} 19 | 20 | 30} 40 | 50 | 60 | x0 
9 = om 2 years. |years. years. years.|years. years. years. 
me | 628 | Aes | soe cles mabe neta sicceat | Geadst 
| = he —s 
2 9.3 8.52 | 65 -54 | 1.10 | 1.6 2.80 | 8.70 | 4.26 
10 7.8 7.16 57 50 94 | 1.3 2.68 | 2.70 
18 Tal 6.98 51 57 | lov | 1 3.37 | 3.49 | 
2 | 63 | 588 | 2 | ‘42 | ‘99 | 1. 2.04 | | 
34 5.7 4.92 39 edd] 1.03 | 1 
42 t.4 3.94 28 -48 | 1.28 | 1.8 
50 | 3.0 | 248 | 19 | (56 | 1.24 | | 
58 5 48 5 24 
60 Top | 
The Accretion of a Forest for a given number of years 
is found by multiplying the accretion of the sample tree for that 
period by the number of trees per acre and the number of acres 
in the tract. If the trees are arranged in diameter classes, the 
accretion of each class is determined, and the sum of accretions 
of all the classes taken as the accretion of the forest. 
The Working Plan of a forest contemplates the economic 
management of the growing crop, so that there may be cut each 
year not to exceed the amount of the annual accretion; or, if 
worked on the rotation plan, so that there may be cut at any one 
time not more than the accretion for the period of rotation, thus 
leaving the capital stock unimpaired. The methods of measure- 
ment described are used in outlining this plan. 
The Estimation of Standing Timber is usually a matter 
of personal experience on the part of the estimator. No meas- 
urements are taken of trees, but the estimate is made by men of 
long experience in the woods. Sometimes their figures are very 
close, but more often they fall short of the actual stand of tim- 
ber. Buying and selling timber lands is based on this method of 
determining the possible crop, both parties sending out their 
