In obtaining the figures previously quoted the Forest Service found
that the average Douglas fir stand at 40 years contains 410 living
trees, most of them between 6 and 15 inches in diameter. At 60
years there are but 265 trees, 145 having died and decayed in the
20-year interval which were suitable for ties or other small timber
products. The remaining trees would have been improved by thinning
to prevent this loss, for the greatest diameter growth is made
when the stand is open, and the ideal is to have just the density
which will get the greatest wood production and still result in
proper pruning and clearing of the trees.

Commenting along this line Mr. T. T. Munger, who conducted the
investigation, says:

"That thinnings are silviculturally practicable and financially
profitable in the Pacific Northwest has been demonstrated. In the
vicinity of Cottage Grove, Oregon, many fully stocked even-aged
Douglas fir stands now about 50 years old, most of them forming
a part of ranches. Many of these stands have been cut over in the
last 10 years and all the material then large enough for piling or
mine timber cut out. This removed about 20 per cent of the stand.
At the present time many of these same stands now contain much
material valuable for small piles, ties and mine timber, yet the
crown canopy is as dense and the trees as close and fine quality
as though no cutting had ever been done in the stand. In fact,
some of the 50-year old stands have already been cut over a second
time, and each time with decided profit to the owner and no damage
to the forest. From one 10-acre block of second growth now 50 years
old, situated 7 miles from the railroad, already 32,000 feet of
mining timber and about 100 50-foot piles have been taken out,