IMPROVEMENT OF THE FOREST 217 



The various methods developed to secure this object 

 are called accretion methods, or methods of accretion 

 cuttings. 



The two-storied system of management is really an 

 accretion method; but since it involves the reproduction 

 of a stand to be grown with the main trees, it was de- 

 scribed under the silvicultural systems. In like man- 

 ner, the systems of reserves involve the same principle of 

 giving individual trees full light. 



One method of taking advantage of an accelerated 

 growth is to make a long period of reproduction under 

 the shelterwood system, The reproduction cuttings are 

 begun earlier than usual. When the seed-cutting is 

 made, the trees left standing are chosen primarily with 

 reference to their ability to produce a more rapid 

 growth. During the lengthened period of reproduc- 

 tion there is thus secured a large growth. This method 

 is employed only where the rotation is relatively short, 

 as, for example, in spruce 100 years of age or under. 

 With old stands there would be little response to the 

 changed light conditions, and hence very little or no 

 light growth. 



Probably the most common method used in Europe 

 is that of underplanting. When the trees have reached 

 their main height-growth and have developed the form 

 desired, the stand is thinned very heavily and under- 

 planted. The aim is to give to the best dominant trees 

 in the stand just the amount of light they can fully utilize 

 in making growth. In order that there may be as many 



