SHELTER-WOOD COMPARTMENT SYSTEM. 93 



2. The Shelter-wood Compartment System, or the Uniform 

 Treatment of a Wood. 



a. Origin and Character. 



The wood is formed, or regenerated, under the shelter of 

 the whole or part of the okl crop, which forms the shelter- 

 wood, and which is retained for some years, until the young 

 generation has established itself and is safe against injurious 

 external influences peculiar to early youth. The regeneration 

 is effected, according to circumstances, by the seed falling 

 from the shelter trees, which in that case become mother 

 trees, or by sowing and planting. In the former case the 

 regeneration is said to be natural, in the latter artificial. 

 In the case of natural regeiieration, one seed year is rarely 

 sufficient ; as a rule two or three such seed years are required, 

 and often artificial cultivation has to assist, in order to pro- 

 duce a full new' crop ; hence, the latter shows in the majority 

 of cases differences of age ranging up to perhaps 15 years. 

 Nevertheless, such differences will be no longer discernible, 

 when the wood approaches the end of the period of prin- 

 cipal height growth, and, for all practical purposes, such 

 woods are considered even aged. 



h. External hangers. 



Owing to the presence of the shelter-wood, the danger 

 from frost, drought and weeds daring youth is very con- 

 siderably reduced, if not altogether obviated ; during the 

 rest of life no difference exists in this respect between this 

 system and the system of clear cutting. There is no doubt 

 that such woods are less attacked by insects than woods on 

 clear cuttings. The chief difference as regards storms is, 

 that the shelter- or mother trees are liable to be thrown. 



c. Production of Wood. 



The quantity of total production is probably the same as 

 in clear cutting. As regards quality it should be noticed that 



