16 BULLETIN 11*76, U. S. DEPARTMENT OE AGRICULTURE. 
ous volume loss. From Table 12 it will be seen that volume losses 
have never exceeded 1 per cent and have averaged 0.37 per cent an- 
nually. Since windfall and deaths from other causes are usually 
heaviest during the first five years after logging (true, thus far, of 
practically all the areas included), this rate should decrease m the 
future, (PI. I.) 
Economic conditions at present do not permit the removal of all 
defective material, and in consequence there are on these plots a 
number of trees showing the effects of mechanical injuries, or attacks 
by pathogenic organisms, some of which reduce growth. Probably 
the most serious of these is mistletoe. This subject early received 
rather careful consideration in marking, so that most of the trees* 
seriously attacked were removed. Excepting the above-mentioned 
case of Douglas fir on the Shasta, mistletoe damage is largely con- 
fined to attacks of the lower limbs of white fir and yellow pine by 
Razoumofskya and of the tops of large decadent white firs by a 
Pharandendron. Pearson, in the Southwest, has shown that a con- 
siderable infestation of mistletoe reduces growth to a marked degree. 
On timber sales made before the advent of the sanitation clause in 
the contracts there remain considerable numbers of old unmerchant- 
able white firs and incense cedars affected with fungi. These trees 
are growing slowly, probably due as much to advanced age as to the 
fungi, most of which attack the heartwood only. 
Even large mechanical injuries, such as basal logging and fire 
scars, have not been found to reduce growth except in smaller trees, 
which are practically girdled. 
Increment borings show that injuries, such as scorching away part 
of the foliage by brush-burning fires, raking off of green limbs by 
falling trees, or broken tops, are always evidenced by reduction in 
the width of the annual rings made during the years immediately 
following logging, in proportion to the amount of foliage destroyed. 
The dense cover of shrubs which, owing to the open character of 
the stands, frequently grows to the bases of the larger trees, un- 
doubtedly reduces the amount of soil moisture available and conse- 
quently their rate of growth. While this fact is usually conceded, 
the extent to which it is true has not been determined. 
VALUE OF INCREMENT. 
So far we have been considering the disadvantages of a heavy 
stand after cutting as regards volume increment without regard to 
quality. There is considerable justification for leaving a certain 
amount of large, high-quality material for value increment, where 
the stand will be accessible for a second cut in a reasonable time, but 
great care should be exercised in selecting trees to be reserved for 
this purpose. The following figures, although they do not represent 
the method of determining national forest timber-sale policies, 
indicate that a profit will result from such stand unless unexpected 
wind or insect damage occurs. 
The valuation of the stand left on the Stanislaus plot 3 at the time 
of cutting, assuming a second cut in 30 years, would be : 
Sale value of timber at time of cutting, $45.20 per acre. 
Value of timber at end of 30 years, with compound interest at 3 per cent. 
$109.71. 
