24 BULLETIN 1176, U. S. DEPARTMENT OF AGRICULTURE. 
survive. Additional cost of logging to protect ^eed trees and advance 
growth is roughly 75 cents per thousand for slash piling and burning, 
snag disposal, and additional blocks, bushing, etc., to protect trees 
from lines, or, for a cut of 20,000 board feet, about $15 per acre. 
These costs are really borne by the Government in reduced stumpage 
rates. Natural reproduction, as compared with planting, will in- 
crease the rotation by 10 or more years. Comparing the two methods 
on a financial basis, disregarding taxes and administrative charges, 
and using the same rate of interest in each case for the respective 
rotations, the ultimate costs are much in favor of planting. At 
present the planting of such areas is inconsistent with the nation- 
wide policy of the Forest Service which gives first consideration to 
completely denuded areas where lack of seed trees makes even slow 
natural regeneration impossible and to areas where rapid growth 
and good markets will insure quickest returns. 
SUMMARY. 
Site is the most important factor in the growth of stands left after 
cutting. On Sites I and II a reserve volume of 6,000 to 10,000 feet 
board measure is justified for increased growth and improved quality 
of second cut. By proper selection of reserves a net growth of 2^ to 
3 per cent annually can be maintained for at least 10 years after cut- 
ting. On Site III, or poorer, silvicultural considerations indicate 
marking aimed to secure reproduction. Other considerations, how- 
ever, do not permit the uniform application of these principles. 
White fir ranks first in rate of growth, followed by sugar pine, 
Douglas fir, yellow pine, and incense cedar. Sugar pine maintains a 
high rate of growth to a greater age or diameter limit than the other 
species. On Site II, or better, indicated diameter limits are roughly 
30 inches for sugar pine, 26 inches for yellow pine, and 24 inches for 
white fir and incense cedar. Corresponding ages range from 150 to 
200 years in present stands. 
In selecting trees to reserve for increased growth the best results 
will be obtained from trees free from defects, with the color and tex- 
ture of bark characteristic of immaturity, pointed tops, dense dark 
green foliage, and crown length equal to 60 per cent or more of the 
total height. 
Leaving trees in groups neutralizes the effects of cutting and dis- 
criminates against pine reproduction. 
The greatest response to cutting can only be secured by heavy 
marking, proper distribution, and careful selection of reserves ac- 
cording to the foregoing statements. Response is greater and more 
prompt on good sites and where cutting frees both root and crown. 
The net rate of volume increment for stands averaging about 
15,000 board feet per acre for Sites I to III has been from 53 to 470 
board feet per acre annually, or 0.34 to 3.46 per cent. Loss by death 
has averaged 0.37 per cent annually. 
Except on Sites I and II, in 10 years' time there has been no appre- 
ciable increase in the amount of reproduction on early sale areas cut 
over lightly by the group selection and shelterwood methods. A 
regeneration period of from 5 to 10 years on Site I and of 20 or more 
years on Site III may be expected. 
