EOKEST PLANTIXG IX THE LAKE STATES 15 
tions in the Mississippi Valley and in Iowa have been discussed at 
length in published bulletins (7o, JfS). The conclusions may be 
summarized briefly. The commercial growing of eastern cottonwood 
by planting deserves consideration as a means of supplying pulp- 
wood, fuel, and farm timbers. It may be expected to yield 15.000 
to 20,000 board feet at 40 years, or 20 cords in 20 years. Well- 
drained bottom lands, even if sandy, are the best planting sites. 
Upland or land covered with sod or a heavy growth of weeds should 
be plowed in preparation for planting, although plowing may not 
be necessary on open cut-over bottom lands where moisture is 
plentiful. Cuttings 10 to 18 inches long from fresh twigs may be 
planted at once or after being rooted in nursery "beds. They should 
be set out in the spring, 7 to 10 feet apart each way. The rapid 
growth of eastern cottonwood makes good returns probable. 
White and green ash, Russian poplar, and box elder have been 
planted on soils which were cultivated before and after planting. 
Under these conditions they have been thoroughly successful even 
in the severe climate of western Minnesota. It is not known whether 
they would be successful without cultivation. Russian poplar makes 
exceptionally rapid growth, but its timber value is uncertain and 
will probably not exceed that of eastern cottonwood. Box elder is 
not a desirable timber tree. 
The ashes, however, are highly valued for many purposes. Green 
and white ash grow naturally in the region on good soils. The 
growing of different kinds of ash by planting and otherwise, chiefly 
in New York, Ohio, and Illinois, has been covered in a separate bul- 
letin {62) from which the following suggestions are taken as being 
presumably applicable in the Lake States: Ash may be recom- 
mended for planting on cleared fields or good forest soils where it 
has grown naturally. One-year or two-year seedlings 6 inches to 
2 feet high are most likely to succeed. They may be spaced 6 to 8 
feet apart in mixture with northern white pine, sugar maple, or red 
oak. The site should be cultivated before planting and for one or 
two seasons after. On soils of medium quality, ash may be ex- 
pected to yield 15,000 board feet to the acre at 60 years when the 
trees average 10 inches in diameter. 
MIXED PLANTINGS 
Plantings in the Lake States are still too young to indicate con- 
clusively the advantages of specific mixtures of species. Since in- 
formation from experiments or experience is lacking, it is necessary 
to limit the discussion of mixed plantings to some general principles 
and suggestions of possible mixtures which seem most likely to prove 
successful. In general, mixed plantings of more than one species 
are desirable because they provide more complete use of the produc- 
tive capacity of the site and a larger product of higher quality and 
subject to more variety of use and market than plantings of only one 
species. If insects or disease attack the plantations and become 
epidemic, they are unlikely to damage seriously more than one kind 
of tree, and the damage to the more susceptible one is less than it 
would be if it were in a pure plantation. Even if one species be 
