7-inch
white pine will be salable, the best fir table was worked upon
a 12-inch diameter basis. Obviously this would show an unfairly
greater yield of a pine forest containing trees between 7 and 12
inches and be very misleading in calculating financial results at
the same age and stumpage rates; yet without the original data
there is no way of reducing both tables to the same basis. As an
example, however, to indicate how the financial possibilities of
second growth can be arrived at if a systematic study is made,
let us take the Douglas fir figures referred to.

DOUGLAS FIR

These are exceedingly reliable. Measurements were taken by the Forest
Service of practically pure fir on about 400 areas in thirty-five
different age stands from 10 to 140 years old, ranging along the
western Cascade foothills from the Canadian line to central Oregon.
Since reforestation investment is likely to be confined mainly to
the more promising opportunities, only such growth was measured
as gave an average representation of the better class of the two
should all the general territory covered be graded in two quality
classes of all around ability to produce forests. On the other
hand, care was taken not to represent the maximum of the better
class, data being taken only from permanent forest land and not
from rich potential agricultural land which might show unfairly
rapid forest growth. The average areas were actually measured and
the number, age, form, diameter growth, height growth, board foot
contents, etc., of all the trees on them were accurately determined.
Trees 12 inches in diameter 4-1/2 feet from the ground were considered
merchantable, and it was assumed they could be used to 8 inches in
the top. From this data were prepared tables and diagrams showing
the average development of trees and stands under fairly favorable
conditions in the region west of the Cascades.

This gave the following yield per acre:

Age of Stand. Feet, B. M. Age of Stand. Feet, B. M.
40 12,400 90 70,200
50 28,000 100 79,800
60 41,000 110 90,300
70 51,700 120 101,500
80 61,100 130 113,000

Let us see how these figures can be used in answering the primary
question of the prospective timber-grower: "Will it pay to hold
my cut-over land for a second crop?"