LOGGING PRACTICE IN THE LAKE STATES 57 
ability of replacing them by other more promising species such as 
white or Norway pine or white spruce, for which the soil is well 
adapted. 
CONVERSION OF ASPEN INTO CONIFEROUS STANDS 
The conversion of aspen into white and Norway pine or white- 
spruce forests can be brought about either by underplanting aspen at 
the rate of 100 to 200 trees per acre or by releasing the young white 
pine or white spruce if they are already on the ground. Conifers 
should be planted in mature stands of aspen only where the aspen is to 
be removed within 10 years after the planting, as otherwise the coni- 
fers may not grow or even live. Paper birch, which is usually found 
in mixture with aspen and other species, should be handled like the 
aspen. 
SLASH DISPOSAL 
There is no special problem in slash disposal. Clearing protective 
strips along roads and leaving the tops so that they will le flat on 
the ground are all that is needed. A desirable practice is to cut 
down the dead birches, since sparks from burning birch snags spread 
fire over large areas. 
Where aspen and birch are cut clean and utilization is very close, 
as when aspen is used for pulp and paper birch for small turning 
bolts, the slash may be left unburned provided strips along the 
logging roads are cleared. Both aspen and paper birch decay very 
rapidly and within two or three years cease to be a fire menace. 
YIELDS AND COSTS 
Aspen stands, as they occur over wide areas, yield on an average 
about 15 cords of merchantable pulpwood in 40 years, or a little 
better than one-third of a cord per acre per year. In Minnesota a 
large part of the aspen finds a ready market at an average stumpage 
price of $1 a cord. In many parts of Michigan and Wisconsin aspen 
is still only little utilized, and the returns from it are uncertain. 
On the better white-pine lands pure aspen with only protection 
from fire often yields in 40 years 4,000 board feet of saw-log material 
and 15 cords of pulpwood. In mixed stands of white pine and aspen 
the yields may vary from that of pure aspen stands to that of pure 
white pine. Aspen reproduction may be secured at the mere cost 
of fire protection in addition to the annual taxes and interest on 
the value of the land. It is doubtful whether more intensive forest 
practice would increase the yields above those in pure aspen stands 
on the better soils, unless the aspen stands were to be converted into 
white-pine or white-spruce stands. 
Conversion of the aspen stands, either by underplanting with coni- 
fers or by cutting out the aspen to release reproduction of conifers 
already on the ground, may be effected at a cost of about $2 or $3 
an acre. The yields found to-day in small well-stocked stands on 
land originally in white pine are indicative of the yields that may 
be obtained under intensive forest management of aspen stands. 
These yields range from 15 to 40 cords, or from 2,000 to 8,000 board 
feet, an acre in 40 to 45 years, 
