30 BULLETIN 24, U. 8. DEPARTMENT OF AGRICULTURE. 
seed trees if they are never utilized, or by the extra cost of removing 
them if they are taken out later. Planting, then, requires a cash out- 
lay. Natural reproduction requires merely a curtailing of present 
profits. The greater-present returns when no seed trees are left may 
often go a long way toward defraying the expense of planting. 
It is questionable if planting would be wise where there is a 
reasonable certainty of securing new stands from natural seeding. 
Wherever conditions are favorable to seed germination, as on lands 
subject to overflow in the spring, but which is only moist when the 
seed falls, and is free from shrubs, vines, or herbaceous plants, 
natural reproduction is reasonably certain and less costly than plant- 
ing. On low ridges or where spring overfiow is uncertain, complete 
dependence can not be placed: upon natural reproduction. 
Planting insures a uniformly stocked stand; the spacing of the 
trees can be so regulated as to obtain more rapid growth during 
early life, thus shortening the rotation, and there is less chance of 
complete failure due to weeds or undergrowth, the absence of high 
water, or an unusually late flood which washes away the seed. On 
land where reproduction by either method is difficult planting is 
preferable. Planting, therefore, will in the future probably be pre- 
ferred to natural reproduction in the Mississippi Valley. 
REPRODUCTION BY SPROUTS. 
Natural reproduction may be obtained either from sprouts or from 
seed. For several reasons sprout or coppice reproduction will prob- 
ably be of comparatively minor importance in the lower valley. 
First, few stands of cottonwood less than 35 years old will be cut, 
by which time the sprouting vigor of the stumps has weakened. It is 
questionable whether sprouts from stumps of this age, even though 
originating at the root collar, will produce as large and vigorous 
trees as the parent stock. The sprouting vigor declines steadily 
after the tree is 20 to 30 years old. At this age the number of trees 
per acre is small. Consequently the sprouts would not form a suffi- 
ciently dense stand to clear themselves readily of side branches. 
These difficulties may be overcome, as, for example, by supplementing 
coppice growth by planting or natural seeding. From present indi- 
cations it would seem that sprout reproduction is applicable only 
to stands managed for pulpwood on a rotation of 10 or 12 years. 
Pulpwood companies in the North which are planting this species 
will undoubtedly find the sprouting of cottonwood of great value in 
securing second growth. The coppice system of reproduction entails 
but small initial expense, and because of rapid growth makes pos- 
sible short rotations. The young age of trees taken for pulpwood 
and the low stumps which it is possible to cut will insure vigorous 
sprouting from the root collar. Six inches should be the maximum | 
