a utilized top and to an 8-inch top. Cubic foot figures are for a uti- 

 lized top and a 4-inch top. These are shown for trees (1) with no indica- 

 tion of rot, (2) with either the lower or the upper section (that part 

 above the first 32-foot log) showing indicators of defect, and (3) with 

 both sections showing indicators. He lists reliable indicators of cull. 



The Forest Survey has found it helpful to show these tables in terms of 

 percent of gross volume that is merchantable so that the figure can be 

 applied directly to gross volume. These are shown to a fixed top in 

 table 6. 



Although Kimmey ' s tables of defect are regional and may not be perfect 

 for any one timber sale area, the chances are pretty good that his figures 

 are better even for local use than the estimates of any forester not 

 trained in forest pathology. 



The comparison of board foot and cubic foot figures in table 6 shows just 

 one more reason for discarding the antiquated Scribner board foot rule. 

 Note, for example, that a 28-inch d.b.h. hemlock tree with both lower and 

 upper bole sections showing rot indicators has a merchantable board 

 foot volume of only 50 percent. The same tree has a merchantable cubic 

 foot volume of 80 percent. The cruise, in board feet, will show less 

 than is actually there in pulpwood. The tree is apt to be left unuti- 

 lized because it hasn't boards enough in it, but the sale may be for 

 pulp. If it is taken out of the woods, the scale by Scribner will cull 

 much of it, but still the pulp is there. The board foot rule measures 

 less in the raft than will actually be taken and used for pulp. 



Tree Decomposition Rates 



How long has this tree been dead? The answer to this question is needed 

 to permit estimates of natural mortality in making forest surveys or 

 cruises in old-growth stands. A study of tree decomposition rates is 

 the first step in developing guides to the estimation of natural 

 mortality. 



Seventy-one trees, poisoned or girdled in a stand improvement study, have 

 been observed annually since 1950. The rate of decomposition of the 

 needles, branches, bark, etc. has been expressed as a percentage each suc- 

 ceeding year. A loss of 25 to 75 percent is described as "half gone". 

 "Nearly gone" is 75 percent loss, and "completely gone" is, of course, a 

 100 percent loss. 



Seven years after death the trees appear as follows: 



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