32 FORESTRY 



or by the artificial introduction of plants or seeds, the general 

 system being known as artificial regeneration. 



Generally speaking, the natural means is the cheaper 

 method. It frequently happens, however, that artificial re- 

 generation is the only treatment possible or, at least, desirable. 

 Such is always the case when there is no old crop already on 

 the area to be dealt with, or when there are too few trees 

 capable of giving seed ; and, again, when it is wished to 

 change the species from that previously grown. Unfavour- 

 able condition of the soil or parent trees may make it 

 inadvisable to adopt natural reproduction. 



With certain trees, particularly Spruce and Scots Pine, 

 natural regeneration is indeed possible, but so many diffi- 

 culties are connected with it, that it is usually both surer 

 and cheaper to completely remove the standing crop and to 

 replace the species artificially. In nearly all cases one must 

 assist natural regeneration to a greater or less extent in order 

 to obtain woods of the desired composition. 



The artificial establishment of woods may be either by 

 sowing or planting. With the latter, in ordinary forest 

 practice, the plants are nearly always raised from seed sown 

 in nurseries ; but cuttings, layers, and root -suckers are 

 also employed. In favour of the direct sowing of forest 

 ground it is claimed that it approaches nature's method of 

 reproduction more closely, that it is usually cheaper than 

 planting, and that it provides a denser crop of young trees. 

 Planting, however, is often preferable. With it there is not 

 the same risk in depending upon a particular season's yield of 

 seed ; it gives a start in age and in power to resist many 

 dangers that seriously affect small plants springing from seed 

 directly sown in the forest. Planting is therefore clearly 

 indicated under difficult conditions, such as high exposed 

 situations, or where there is a strong growth of grass or 

 other herbage. For the filling of vacancies that have 

 occurred in recently stocked areas, plants, not seeds, are used. 



If from economic grounds sylviculture is to be practised 

 with as small an expenditure as possible, the choice of 



