Running levels to control barometric work. 



kept of what trees will probably die out through crowding 

 and shading. 



As large a number of felled trees of different diameters as 

 practicable are measured. If logging is going on this can be 

 done in the works. Besides the diameter at breast height, the 

 measurement of growth at breast height or on the stump is 

 made by counting rings back for ten years more or less. Differ- 

 ent types of trees are classified by height as well as diameter. 

 This adds to the accuracy of the figures but is not always neces- 

 sary. The best and cheapest way can be decided on the ground 

 by the forester. 



The rate of height growth is also determined, and the volume 

 of the trees at different ages is computed. This is often a long 

 and somewhat expensive process, but for practical purposes it is 

 possible to shorten it greatly by certain slurring methods which 

 give the desired results for local areas. 



From the volume so obtained for trees of different diameters 

 and growth between different ages, the future growth and yield 

 can be predicted. 



The forest owner may fix the most profitable size at which 

 to cut, and may know the yields of merchantable lumber at 

 future dates after such cutting. He can definitely plan what 

 his forest is going to be worth, as well as what it is worth, and 

 can figure whether he will get good interest on his money if it 

 is left invested in certain tracts of land. 



27 



