METHODS AND PRACTICE 159 



planted in any crop may usually consist of this species, 

 apart from hopeless soils or exposed situations. Bad 

 results often arise from the use of larch in a mixture, 

 owing to the fact that it is allowed to get ahead of the 

 other species too far at first, leading to their partial 

 suppression and weakening at a critical period. Larch, 

 when mixed Avith slower growing species, should be freely 

 pruned back during the first ten or fifteen years, and 

 entirely removed by the twenty-fifth or thirtieth year, 

 unless required for filling up gaps in the permanent 

 crop. 



Other trees of this class are ash, birch, Spanish chest- 

 nut, and spruce, all of which give saleable poles earlier 

 than most species, and can be used in mixture with trees 

 of an average, or rapid rate of growth. In exposed and 

 windy districts, or on thin soils, however, it is rarely 

 advisable to depend too much upon intermediate thin- 

 nings after the first twenty years or so. Any break in 

 the leaf canopy after that age is a dangerous occurrence, 

 and may lead to the destruction or stunting of the crop, 

 unless extreme care is exercised. 



The use of species for suppressing surface growth may 

 or may not be necessary on ordinary soils, but on poor, 

 peaty ground covered with heather, bracken, Vacci7iiu7n, 

 etc., such species are desirable, if not absolutely necessary, 

 to bring about satisfactory results, especially on exposed 

 sites. One important feature of these species must 

 always be cheapness, and ability to thrive under the exist- 

 ins: conditions from the first, otherwise no advantasfe is 

 gained in using them. The most suitable species for the 

 worst classes of soils are birch and mountain pine, but 

 the latter is, of course, useless for anything except fire- 

 wood, and birch must be planted closely to produce the 

 desired result. The system adopted in Jutland and else- 

 where, of planting mountain pine and white American 



