SAW-TIMBER GROWTH AND 
MORTALITY IN MONTANA 
++ OUT OF A GROSS 
ANNUAL GROWTH OF 
849 MILLION BOARD 
FEET 
Lear feet Wee 
243 ttlion 
jltlligled beg ' 
We es 
ACMUCING the 
Oppective growth 
te 606 million 
board feet 
FicGureE 36. 
matter where it occurs. With that policy clearly 
defined, the effort has been directed toward carrying 
it out and the problem is being tackled aggressively. 
During the 1930’s an all-out effort was begun 
to suppress blister rust. The lack of an equally 
forceful attack on the other enemies of the forest, 
particularly the mountain pine beetle, has been 
the principal weakness in the protection program. 
Reduction of losses from the present level requires 
a well-rounded attack. 
Postponing the mortality of mature trees by con- 
trolling insect attacks is profitable only to the ex- 
tent that the timber saved can be utilized before 
a recurrent infestation. For example, if mountain 
pine beetle control is to pay, the control should 
be tollowed ‘by utilization of the susceptible trees. 
In the past it has seldom been practicable to obtain 
prompt utilization, because lodgepole pine and 
several other species have had only a limited mar- 
Forest Resources of Montana 
ket. Thus, the matter of increasing industrial de- 
velopment to secure complete utilization is of pri- 
mary importance in managing Montana’s forests. 
Increasing Gross Growth 
If it were possible to eliminate mortality losses, 
the net annual saw-timber growth in Montana 
would rise from 38 board feet an acre to 54 board 
feet. Even then, however, the net growth would be 
below the desired rate. If the net annual growth 
of the average acre is to be raised from 38 board 
feet to 85 board feet, gross growth will have to be 
increased at the same time losses are being reduced. 
Merely to say that the gross forest growth in 
Montana should be increased gives no idea of the 
dimensions or complexity of the task ahead. ‘To 
increase the gross forest growth involves all of the 
things a forester generally includes in the term 
“silviculture.” Some forest lands are so overcrowded 
that the trees have stagnated. Other areas are under- 
stocked. Some are deforested. Many trees have 
passed their prime and are growing slowly. There 
are too many of some sizes of trees and too few 
of others. Less desirable species are gaining ascend- 
ency over preferred species. A major part of some 
of the older stands is cull trees that contribute 
nothing in the way of growth but compete for 
space with normal trees. ‘The task of forest man- 
agers, therefore, is to correct these deficiencies with 
the objective of developing a fully productive, 
vigorous, fast-growing forest. 
The larger problems of management arise from 
the advanced age of much of the timber. In western 
Montana, for example, stands on 45 percent of the 
commercial forest are over 120 years old. Many of 
the trees in these stands, in addition to being poor 
risks, are growing very slowly. Yet they should not 
all be cut at one time or there will be a shortage 
of large timber while younger stands are growing 
to maturity. The conflicting objectives of spreading 
the old timber for a sustained yield and cutting it 
before it dies require a calculating eye on each 
tree to determine its life expectancy. 
Hand-in-hand with the problem of managing 
these old stands for a sustained-yield cut to offset 
the shortage of intermediate-age timber in the next 
few decades, is the one of securing ample reproduc- 
tion of the desired species (fig. 37). Studies in the 
ponderosa pine type, for example, show that this 
species reproduces best in stands of 3,500 to 5,500 
ae 
Or 
