Gross growth in board feet Scribner for all softwood sawtimber species 

 was equivalent to 2.5 percent of the working circle's total board foot volume. 

 In comparison, gross growth of softwood species in the entire Rocky Mountain 

 region was equivalent to 2.2 percent of both the total cubic foot and board 

 foot softwood volumes (USDA Forest Service 1978). 



Most of the growth in the working circle occurred in Douglas-fir and 

 lodgepole pine. Table 18 shows 79 percent of the cubic foot growth for all 

 softwood species, as well as 81 percent of the board foot growth in these 

 species, occurred in Douglas-fir and lodgepole pine. 



Gross growth by diameter class data indicates smaller diameter trees 

 grow more quickly than larger diameter trees. In other words, the growth 

 rate decreases with age (see Tables 19 and 20). This data also shows that 

 over half of the forest's gross growth, both in cubic feet and board feet, 

 occurred in the two smallest diameter classes. The large amount of growth 

 shown in the smallest diameter class is primarily caused by ingrowth. 



Mortality The data collected in 1978 indicates mortality was occurring 

 at a low to moderate rate. Mortality in softwoods, expressed as a percentage 

 of the total softwood volume, was 0.3 percent for both cubic foot and board 

 foot volumes. Mortality in the entire Rocky Mountain region was estimated at 

 0.5 percent of total volume (USDA Forest Service 1978). In 1978, mortality 

 equalled 13 percent of the cubic foot gross growth and 12 percent of the 

 board foot gross growth taking place in the working circle. 



Tables 19 and 20 show mortality rates generally decline as diameter class 

 increases until they reach diameters in the mid-twenties. At that point the 

 trend reverses and mortality rates increase as the diameter class increases. 

 Eventually mortality rates become high enough and the growth rate slow 

 enough that the trees are dying faster than they are growing. 



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