CHAPTER IX. FORESTS 
Losses of Forest Resources 
The mortality of standing timber in Unite? States forests re-= 
sulting from natural causes is estimated at about 2.15 billion 
cubic feet annually. In terms of sawtimhber (Table 19), annual 
mortality from all natural causes totals about 8.7 billion board 
feet. These losses represent about 0.5 percent of the total 
stand of timber and about 15 percent of the current anmial growth 
of timber crops. These losses result primarily from insects, 
fire, disease, and wind. 
Losses due to raduced growth of forest crops are substantially 
higher than the direct mortalities. Destruction of seedlings and 
saplings by fire and other natural causes, damage to larger trees, 
and deterioration of soils reduce the productivity of forest lands 
and result in losses of potential growth amounting to 6.5 billion 
cubic feet annually, including ahout 25.7 billion board feet. of 
sawtimher. 
Serious losses of lumber and other forest products in buildings 
and other structures also result from fire ad other natural causes. 
Estimated annual losses of forest resources in the United States 
are given below. 
i nent ten Wit emENOntal tyil Siss fasiahey fa Ttagoe ss oom 
sie Aula $ 3 Cull increase and 
Cause : Timber 3 Sawtimber : growth loss 
: Million : Billion Million :Million Billion Million 
s Cutts : bdeutte dollars s:cusitt. bd. ft. dollars 
Fire : 750) =: 2-0 18 ; 2,550 10.0 50 
Insects 1/ 21h 950) wiencralrsS Siiee: 0) 0.2 2 
Disease Se OM me NOT, Guns 296 5.5 50 
iiseel laneous 2//iaa, 1 3000) 2) 5 1B eter SOM Os0 50 
Total 2,150 8.7 91 6,550 98 25.7 1 Ge 
1/ Cull inerease and growth loss due to insects are believed 
to be considerably greater than shown, but informetion is 
lacking as a basis for more precise estimates. 
ey Wind, rodents, lozgzing casualties, etc. 
Fire Losses =— Timber 
About 3.5 million acres of forest land were burned over anmualiy in 
the United States during the period 192-51, This represented a loss 
5 eal So 
