﻿30 BULLETIN" 24, U. S. DEPABTMENT OF AGBICULTUBE. 



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 overflow 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 



