164 Studies in Forestry [CHAP. vm. 



and Douglas Firs, an admixture of Spruce could only endanger 

 the stability *of the crop and increase the risk from injurious 

 insects ; whilst, on soils naturally best suited for Spruce, the 

 introduction of these other genera can be of considerable advan- 

 tage in the protection afforded against windfall and insects. 

 The formation of mixed forests of Scots Pine and Larch, so 

 often hitherto favoured in Scotland, is not one that can be 

 recommended -; for it is not in conformity with the principles 

 of sylviculture. And practical experience has shown that the 

 theoretical point of view in this matter is correct. 



The most advantageous results are obtainable when a happy 

 choice has been made combining light-demanding and shade- 

 bearing genera, and when the former retain for a long time 

 the early advantage they gain owing to their more rapid growth 

 during the. earliest stages of development. Where it is suited 

 to the soil, Beech, owing to the very superior .quality of leaf- 

 mould formed by its dead foliage, or Hornbeam, yields the 

 best results as matrix from a purely sylvicultural point of view. 

 But, in Britain, financial considerations undoubtedly deserve 

 greater attention from the land-owning classes than the scientific 

 sylvicultural principles that ought to underlie .the treatment 

 of the State lands and Crown forests if they were properly 

 administered ; hence Spruces, -Silver Firs, Douglas Fir, and in 

 certain cases Austrian and Corsican Pines, are the forest trees 

 most deserving of cultivation. Even though these species may 

 be to a certain, and often to a considerable, extent influenced 

 in their development by the other species of more rapid growth, 

 yet even then they are still capable of yielding timber of good 

 marketable quality and dimensions. Where, however, the 

 interference with their normal .development is only compara- 

 tively slight, the quality of the .timber of the above kinds of 

 forest trees decidedly gains by admixture. 



And when once the choice of species has been made, the 

 proportion which they shall each bear to the total number of 

 plants per acre requires equally careful consideration. The 



