COTTONWOOD IN THE MISSISSIPPI VALLEY. 41 
a. # 
It is fair to assume that artificial thinning would be followed by 
somewhat similar results. 
Economie conditions, such as markets for small material, extent of 
investment, etc., will govern to a large extent the practicability of 
thinnings. In the lower Mississippi Valley there is at present little 
if any demand for the small-sized material which thinnings would 
yield. Pulp companies, with mills in Indiana and Ohio, have fre- 
quently purchased peeled cordwood of small dimensions as far south 
as Memphis. If such companies find it profitable to establish plants 
in the lower valley where there are extensive areas covered with 
young willow and cottonwood, a market might be expected to develop 
rapidly for the products of thinnings. While in some instances this 
small material may now be disposed of for fuel, braces, small poles, 
etc., as a rule it can not be profitably marketed. 
There is danger in making thinnings too heavy and so permitting 
the entrance of objectionable undergrowth. Unless there is an under- 
story of a more tolerant tree, such as green ash, sycamore, hackberry, 
or silver maple, only very hght thinnings are advisable. In such a 
case the slower growing trees clear the fast-growing cottonwoods of 
side branches, shade the ground, and prevent the starting of grass 
and undergrowth. 
If the rotation of cottonwood for lumber production may easily 
be shortened at least five years by thinnings without diminishing the 
yield per acre, thinnings might in some instances be justified on finan- 
cial grounds, even when yielding no direct return. The saving. of 
five years’ interest on the investment in land and taxes with interest 
would certainly justify, under some conditions, an investment in 
thinnings. For example, the cost of maturing a crop of cottonwood 
in 80 and 35 years would approximate $77.97 and $112.07, respec- 
tively. This represents a saving for 30-year-old stands of $34.10. 
It is not improbable that two thinnings at the ages of 10 and 18 
years, respectively, might shorten the rotation, so as to result 
in practically the same yield at 30 years as it ordinarily re- 
quires 35 years to produce. The costs of such thinnings should not 
exceed $2 and $5 per acre, respectively, which compounded with in- 
terest at 7 per cent would represent an outlay of $19 at the end of 
the 30-year rotation. In other words, the investment in thinnings 
could be expeeted to return 7 per cent interest like the rest of the 
investment, provided it lowers the cost of the crop $19 by shortening 
the rotation. As a matter of fact, an additional profit of $15.10 
would result in this case, represented by the difference between $34.10, 
the saving in the cost of the crop, and $19, the cost of the thinning. 
With a larger investment, as in the case of planting, the difference in 
favor of thinning would be still more pronounced. If the cost of 
