FACTORS INFLUENCING NATURAL REPRODUCTION 1 7 



are in the transition stage between the unmanaged forest 

 of the past and the managed forest of the future. After the 

 first cutting which utilizes the old overmature trees the possi- 

 bilities and necessity of cutting systematically to secure re- 

 production will be seen. 



Factors Influencing Natural Reproduction. — The method 

 of cutting is only one among a number of factors which con- 

 trol the establishment of natural reproduction, such as cli- 

 matic conditions (which is the dominating factor), occurrence 

 of seed years, grazing and other injuries by animals, insects, 

 fungi and fire. All these factors, outside of what direct 

 mechanical influence some of them may exert in destroying 

 established reproduction, affect the start and early develop- 

 ment of reproduction through influence upon such funda- 

 mental factors as temperature, moisture and light which are 

 of direct controlling importance. For successful natural re- 

 production there must be: 



(i) Abundant seed supply in excess of that destroyed by 

 rodents, insects and other agencies ; 



(2) Favorable conditions for germination of seed; 



(3) Favorable conditions for the growth of seedlings. 



Each species is likely to have different requirements and 

 will vary more or less in its own requirements in different 

 parts of its range. The silviculturist should be equipped 

 with a definite knowledge of the basic requirements for nat- 

 ural reproduction of the species with which he deals, and 

 should also know the effect in establishing and maintaining 

 these requirements which methods of cutting, fire, grazing, 

 etc., possess. Supplied with this knowledge he can utilize 

 cuttings, fire and other means, so far as control of them may 

 be in his power, to establish and maintain the conditions 

 requisite for reproduction. 



