40 BULLETIN 1291, U. S. DEPARTMENT OF AGRICULTURE 
will last through at least one rotation. Planting of small areas of 
conifers in large aspen areas could be done at smaller expense and 
would serve to speed up greatly the replacement of aspen where 
natural stands of conifers are at great distances. The replacement 
which might naturally require 250 years could be reduced to about 
80 by the establishment of three to four seed trees per acre at a 
cost of perhaps $2 per acre. This cost would be chargeable to the 
first merchantable crop, consisting not of the trees planted but of 
their offspring, which would presumably mature some 250 to 300 
years after the planting. The annual charge would be only 0.6 
cent per acre on this basis, but it presupposes, as before, the certain 
knowledge of the inferiority of aspen to conifers for all general 
and special purposes far into the future. Under present circum- 
stances even this activity in artificial transformation would seem 
unwarranted, particularly in view of many unsuccessful plantings 
of Douglas fir, western yellow pine, and Engelmann spruce under 
aspen. 
It must not be inferred that aspen is a hindrance to artificial re- 
forestation, for the success of tolerant conifers is greatly increased 
by aspen cover. Results in the vicinity of the Great Basin Experi- 
ment Station in central Utah show this clearly (10) ~ 
On an area of aspen (site quality 2) at about 9,000 feet elevation, 
Engelmann spruce was planted under a virgin stand and also on 
areas where one-quarter, one-half, three-quarters, and all the timber 
had been removed. Five years after establishment: 
61 per cent were alive under virgin stand. 
29 per cent were alive where one-fourth of the stand was cut. 
18 per cent were alive where one-half of the stand was cut. 
11 per cent were alive where three-fourths of stand was cut. 
1 per cent were alive where all timher was cut. 
A similar series of plots under aspen at 7,800 feet elevation (site 
quality 4) in which Douglas fir was used, gave, after three years, the 
following results: 
32 per cent were alive under virgin stand. 
31 per cent were alive where one-fourth of stand was cut. 
52 per cent were alive where one-half of stand was cur. 
27 per cent were alive where three-fourths of stand was cut. 
8 per cent were alive where all of stand was cut. 
Experimental plantings indicate that Englemann spruce can be 
introduced with a fair degree of success in aspen stands within the 
spruce-fir type, except on south slopes. In general, growth on such 
plantations is less vigorous than in the open at high elevations. 
Douglas fir and western yellow pine can be planted with success, in 
years of favorable rainfall at least, in the lowest of the aspen, al- 
though the stands must usually be thinned within a few years to get 
the most rapid and vigorous growth, particularly in the case of west- 
ern yellow pine. 
APPLIED MANAGEMENT IN THE FIELP 
The perpetuation of aspen stands is always advisable, for the 
forest cover has a great indirect value as a protection to watersheds 
and as a nurse tree to conifers, aside from any commercial value. 
Therefore, grazing should not be allowed to wipe out aspen under 
any circumstances, for aspen can not reclaim the lost areas again. 
Old even-aged stands without an understory of sprouts and cut-over 
