ESTABLISHING FORESTS BY PLANTING 377 



22. Regular and Semi-regular Spacing 



In nearly all planting operations in the United States the trees 

 are set by some system of regular or semi-regular spacing, i.e., an 

 effort is made to plant them in rows a uniform distance apart and 

 at equal distances in the rows. In practice, however, absolute 

 uniformity is rarely attained nor is it desirable when it entails 

 additional expense. Where the same number of trees per acre 

 is used in the planting, all methods of regular or semi-regular 

 spacing show inappreciable differences after one or two thinnings. 

 The question of cost, therefore, should determine the method best 

 to use on any particular site. 



23. ADVANTAGES OF REGULAR SPACING 



The advantages of regular spacing as compared with irregular 

 spacing are as follows: 



a. The trees being in rows, blanks can be filled more readily 

 and the young trees can be found more quickly in protecting 

 them from competing vegetation. 



b. The trees have a more uniform growing space and, as a result,- 

 the site is more completely occupied. 



c. Cultivation, when necessary, can be resorted to without the 

 necessity of hand labor. 



d. The early thinnings can be removed more readily and at 

 much less'cost. 



e. When mixed stands are desired, the required mixture can 

 be more readily attained. 



When 2- to 5-inch trees are planted on sites covered with grass 

 and other herbage, unless the trees are set in rows it is impracti- 

 cable to attempt to fill the blanks for a period of several years or 

 until the young trees clearly show above the herbage. This nec- 

 essary delay in filling blanks adds greatly to the cost, because 

 much larger stock must be used than when the filling is done the 

 year following the formation of the plantation. On open sites it 

 is also often necessary to protect the young trees from weeds, 

 grasses and other herbage which, if not removed, will overtop and 

 smother them during the first year or two after planting. Econ- 

 omy in providing this protection demands the finding of the 

 young plants amongst the herbage without undue waste of time. 

 It is sometimes necessary to cultivate plantations for a period of 



