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?"

Obviously no certain answer can be printed here, not only because
no uniform stumpage prices or carrying charges can be predicted but
also because individuals may differ as to what profit is necessary