58 BULLETIN 1402, U. S. DEPARTMENT OF AGEICULTUEE 
The most important source of new growth on cut-over lands lies 
in the small trees below 12 inches in diameter at the time of cutting. 
On good sites with well-distributed advance reproduction, of which 
two-thirds is saved during logging, the growth in a 30-year period 
will amount to between 9,000 and 10,000 feet per acre. On medium 
and poor sites the growth on this class of material will be around 
6,000 and 3,000, respectively. 
The total groAvth to be expected with good practice varies from 
150 board feet an acre each year to 500 or 600, depending primarily 
on site, thus exceeding by about 50 per cent the growth under the 
minimum timber-growing measures discussed in the first part of this 
bulletin. At an average stumpage rate of only $3 per thousand feet 
board measure, the value of the annual increment will range from 
$0.45 to $1.80 per acre. In addition, the volume of merchantable 
timber reserved is to be counted on, and this will naturally be of a 
higher quality in the future than it is at the time of the first cutting. 
In short, attainable growth to-day in the pine region is sufficient to 
justify commercial timber growing when carried on as part of a 
going operation. 
Nearly every extensive area of timberland will contain a wide 
range of site quality, varying often from the best to inferior lands. 
Holdings on which the land is predominately good, even with small 
areas of poor lands, oiler naturally the best opportunity for the 
growing of timber. It is estimated that in the pine region as a whole 
not over 20 per cent of the private forest lands are of a poor site 
quality, and the great bulk of these are on the east slope of the 
Sierras. 
The great advantage of the partial cutting plan proposed is obvi- 
ously that it makes possible a second cut within one-third to one-half 
of the number of years required to grow a merchantable tree from 
seed. 
Even the rapid gi^owth under partial cutting does not represent 
the full productive capacity of the land. On the west slopes of the 
Sierras, full stands of even-aged young timber produce in a period 
of 80 years, 80,000 board feet per acre on good sites, 50,000 on 
medium, and 30,000 on poor sites as measured by the international 
log rule. On the east slope of the Sierras, with a rotation of 120 
years, the yields for the same three classes of land are 83,000, 55,000, 
and 27,000 board feet, respectively. The longer period required 
to grow merchantable timber makes it particularly important on the 
east slope to save the advance reproduction, which already has a 
good start, rather than to wait for new seedlings to come in and go 
through a period of very slow juvenile growth. 
Until planting becomes possible these figures can not be attained 
on large areas; they indicate the rapid growth possible, especially 
on the better lands. As more and more intensive measures become 
possible, growth can be still further increased. 
BASIC PRINCIPLES OF FULL TIMBER CROP PRODUCTION 
The decision to grow full timber crops for future cuttings is one 
that must be made in advance of logging. However simple and 
alluring it may seem to substitute planting for the advance repro- 
duction and seed tree plan, the latter under present .conditions is 
