32 



method of planting, silver maple is referred to by Sv and sugar maple 



bySg: 



Sv Sg Sv Sg 



Sg Sv Sg Sv 

 Sv Sg. Sv Sg 

 Sg Sv Sg Sv 



In plantations the average annual rate of growth of silver maple 

 is approximately one-third inch in diameter and 2 feet in height, 

 while that of sugar maple is about one-half as great. Sugar maple, 

 however, is shade enduring, and even though overtopped by the sil- 

 ver maple will continue to grow. 



With a spacing of 7 by 7 feet, as given in the diagram, the silver 

 maple should, at the end of eighteen years, average about 35 feet in 

 height and 6 inches in diameter, and the suger maple should be 3 inches 

 in diameter and from 15 to 20 feet high. The silver maple should be 

 removed as fast as it becomes a serious menace to the sugar maple. 

 Its complete removal will leave a pure stand of sugar maple, spaced 

 10 by 10 feet in rows running diagonally to the original ones. 



SUGGESTIONS FOR PLANTING. 



Before attempting to establish a forest plantation the behavior of 

 certain species when planted with others should be clearly under- 

 stood. Larch is a pronounced light-demanding tree, and if planted 

 with another species whose rate of growth is equal to or greater than 

 its own it will suffer severe^. The intolerance of walnut leads to 

 such heavy natural thinning that the crown cover is broken and 

 grass obtains a foothold. But both larch and walnut might be under- 

 planted with some slower-growing, shade-enduring species to the 

 general improvement of the plantation. Again, it is quite possible 

 that a mixture of catalpa and Osage orange would be beneficial for 

 both species. 



Once planted, the various species differ in the amount of care which 

 must be given them. A close-spaced larch plantation needs to be 

 cultivated for only a few } T ears, and will then form excellent poles 

 without further attention. On the other hand, to secure straight, 

 healthy catalpa trees, it is advisable to cut them back two or three 

 yenrs after setting, and to select the best of the resulting sprouts for 

 the permanent trees. Dead branches should be pruned wherever 

 their presence might lay the trees open to disease. Pruning is an 

 important factor in assisting Osage orange to grow straight enough 

 for fence posts. 



Approved: 



James Wilson, 



Secretary of Agriculture. 



Washington, D. C, February 26, 1907. 



[Cir. 81] 



O 



