THE PRINCIPLES WHICH DETERMINE SPACING 55 



ticed has led many foresters to consider a stand of from 300 to 

 600 plants per acre 2 or 3 years after seeding an acceptable 

 stand. The author believes that disappointments will arise from 

 this practice and that the employment of more intensive methods 

 and more seed per acre will result in fewer failures and assure 

 much denser stands than those attained under present practice. 



5. THE DENSITY OF THE STAND FROM PLANTING 



In general, the principle which applies to the most acceptable 

 density of reproduction in direct seeding also applies to spacing in 

 the formation of plantations, i.e., the canopy should close within 

 a period of from 6 to 12 years. This can be attained by planting 

 with a much smaller number of plants per acre than it can by 

 direct seeding. 



Spacing varies from less than 4 square feet of growing space for 

 each plant to 64 square feet or even more. Even in countries where 

 forestry has been long established, there is still much controversy re- 

 garding the best spacing distance for different species on different 

 sites. Mayr 1 states that the better the soil and the warmer the 

 climate, the further apart the trees should be spaced. Failures 

 result from wide spacing on poor soils and in cold regions. Close 

 spacing is recommended on steep declivities and on dry sites 

 where the trees tend to develop crooked stems. Moderately close 

 spacing is recommended for such species as oak and larch that 

 require crowding in order to develop straight stems. On the 

 other hand, white pine, Douglas fir, and most species of spruce 

 and fir form a good shaft under wide variations in spacing. 

 Change in soil quality and in the character of the vegetation on 

 the ground often necessitates a change in spacing. 



The more important factors which have a direct bearing upon 

 spacing in planting operations are: 



a. The size of the stock. Large plants should be wider spaced 

 than small ones. 



b. The character of the stock. Transplants should be wider 

 spaced than seedlings. 



c. The site. The plants should be wider spaced on good sites 

 than on adverse sites. 2 



1 Mayr, Heinrich : Waldbau auf naturgesetzlicher Grundlage. Berlin, 1909. 



2 Plantations in semiarid regions where the available soil moisture is only 

 sufficient to sustain a wide-spaced stand are an exception to this rule. 



