SOIL CONDITIONS 141 



is helpless. He must have the assistance of the 

 entomologist. 



In questions of pure silviculture too, where there 

 is reasonable ground for assuming that practice 

 would be sufficient, the forester is dependent on 

 the laboratory investigator. Questions as to the 

 capacity of certain soils to grow certain trees are 

 settled on broad lines by experience. -Neverthe- 

 less it is frequently found that trees planted on 

 soils which generally speaking should suit them, 

 may fail. The soil may have all the ingredients 

 in sufficient quantity necessary for the growth of 

 the trees, and yet the trees either will not establish 

 themselves, or after a brief period their normal 

 growth ceases. This experience is most commonly 

 met with in the case of plantations on moorlands, 

 and has nothing to do, either with the fertility of 

 the soil or climatic conditions. The presence of 

 the various kinds of "pan" goes far to explain 

 things, but further knowledge is wanted. Exten- 

 sive investigations have taken place on the con- 

 tinent, notably by Dr Miiller in Denmark, and some 

 light has been thrown on the question. Its solution 

 will be of particular interest to us, as it has become 

 imperative that we increase our forest area, and it 

 is mainly on the moorlands that this must take 

 place. 



As a result of faulty observation, forestry is 

 not infrequently worked on lines which defeat the 

 desired end. It has for long been the custom to 



