MANAGEMENT. 



53 



The elapsed 14 years had thus been sufficient, with the large increase 

 in light and growing space from the tie culling, for their growth not 

 only to tie size, but to the much more valuable dimension of large 

 poles. A measurement of the rings of annual growth on the stumps 

 of the trees thus cut for poles gave the results shown in Table 37. 



Table 37. — Increase in growth at the stump, resulting from removal of the largest trees. 

 (Chestnut type, quality I, 46 years old, thinned 14 years before; area about 3 acres.) 





Average diameter in- 

 side bark at time of— 



Average width of ring. 



Diameter 

 at time of 

 cutting if 

 original 

 rate of 

 growth had 

 continued. 



Increase i 

 in rate of 

 average 

 annual 

 growth 

 in volume 

 as result 

 of thin- 

 ning. 





Stump diameter 

 class. 



Thinning. 



Final 

 cutting. 



Before 

 thinning. 



After 

 thinning. 



Basis. 



Inches. 

 12 



Inches. 

 7.8 

 7.9 

 9.4 

 9.3 

 9.6 

 9.6 

 9.8 

 7.2 

 8.2 

 11.1 



Inches. 

 12.4 

 13.0 

 13.9 

 15.0 

 16.0 

 16.9 

 18.2 

 18.8 

 20.2 

 21.5 



Inches. 

 0.13 

 .12 

 .15 

 .14 

 .15 

 .15 

 .16 

 .11 

 .16 

 .17 



Inches. 

 0.19 

 .19 

 .18 

 .22 

 .24 

 .24 

 .30 

 .39 

 .30 

 .40 



Inches. 

 11.3 

 11.3 

 13.5 

 13.3 

 13.7 

 13.7 

 14.2 

 10.3 

 12.7 

 15.8 



Per cent. 

 3.1 

 4.7 

 0.9 

 4.0 

 5.3 

 7.6 

 9.6 

 34.0 

 26.2 

 12.3 



Stumps. 



13 



5 



14 



6 



15 



19 



16 



9 



17 



6 



18 



11 



19 



1 



20 



2 



21 



1 







i Derived by means of the formula: 

 (c— b) 100 



1= 



nxa 

 Where I=per cent of increase in rate of average annual growth in area, as a result of thinning: 

 a= surface area of stump at time of thinning; 



b= greatest possible surface area 14 years after thinning if original rate of growth had continued; 

 c= actual surface area 14 years after thinning; 



n= interval between thinning and final cutting— in this case 14 years. 

 These percentage figures are directly applicable to volume grov/th if the total height and form factor 

 are constant. This assumption is made in the above column. 



With the heights and form factors of the trees constant, it is 

 evident from Table 37 that the yearly growth in volume increased 

 by from 1 to 34 per cent as a result of thinning. Since the percentages 

 of increase given in the table are based upon the average growth 

 before thinning and not on the actual rate at which the trees were 

 growing when the thinning was made, they may be taken as con- 

 servative. As a matter of fact, the faces of the stumps showed that 

 during a period, varying with individual trees, of from 8 to 19 years 

 just preceding the thinning the rate of growth had been considerably 

 slower than before. This shows that the trees had begun to be 

 crowded or more or less suppressed by their neighbors. It is prob- 

 able that even if the trees had survived this competition during the 

 14 succeeding years they would have increased very little in diameter. 

 By the removal of their larger neighbors, however, they were 

 enabled to put forth new foliage in such abundance that their sub- 

 sequent growth was more than doubled. Though their growth in 

 height may not have been quite so rapid as in a denser stand, it was 

 nevertheless sufficient to produce excellent poles. 



