considerably exceeded as the Montana forest is cut 
over and restocked with thrifty stands. 
Net annual growth of live saw tim- 
ber and primary growing stock 
Primary growing 
Live saw timber stock 
(million (million 
bd. feet) cu. ft.) 
WesterngMontanaltsaassiee eae 346 97 
asternzMontanaremten eae 260 144 
AR otal eee ae een ste 606 241 
At present 60 percent of the net cubic-foot tim- 
ber growth in Montana occurs east of the Con- 
tinental Divide. This may seem strange, consider- 
ing that only 43 percent of the commercial forest 
area lies in eastern Montana and that this forest 
has on the average a substantially lower growth 
capacity than the forest of western Montana. Here 
again the answer lies in the character of existing 
stands. One-third of the saw-timber area west of the 
Divide is overmature, growing slowly, and _ suffer- 
ing heavy losses from insects and disease. This 
overmature condition is much less common in east- 
ern Montana. Proportionately, much more of the 
eastern Montana commercial forest bears young 
stands, many of which are in the stage of most rapid 
growth. 
The cutting of the overmature stands in western 
Montana is gradually changing the picture, and in 
MAJOR BODIES OF 
DEAD TIMBER IN MONTANA 
FicurE 23. 
the long run we may expect the net annual growth 
there to be substantially higher than in eastern 
Montana. As a matter of fact, inasmuch as the 
western Montana estimates are based on measure- 
ments made in the middle thirties when precipita- 
tion was below normal, current annual growth in 
that area is no doubt somewhat higher than indi- 
cated. The majority of growth measurements in 
eastern Montana were made following World War 
II, during a period when precipitation was slightly 
above normal. 
26 Forest Resource Report No. 5 U. S. Department of Agriculture 
