38 PURE AND MIXED WOODS 



On the other hand, mixed woods are more difficult to 

 manage than pure woods, and have the serious disadvantages 

 that the various species often mature at different ages, and 

 that the timber, when felled, is not all of one grade. Again, 

 in a mixed wood the less valuable species is occupying land 

 which might be occupied by the more valuable species. In 

 these respects pure woods have the advantage. 



On the whole the advantages of mixed woods on a large 

 area outweigh the disadvantages, though on small areas pure 

 woods may often be preferable. 



The advantages of a mixed wood will only be realized if 

 the following conditions are attended to : 



1. The soil and climate must be suitable for all the species 

 chosen. 



2. The mixture must be such that the fertility of the soil 

 is preserved or improved. 



This practically means that the soil-improving species must 

 appear in every wood, and that light-demanders must be 

 mixed with shade-bearers. 



3. The mixture must be so arranged that one species does 

 not outgrow and kill the others, thus establishing a pure wood. 



In this connexion the rate of growth in height of the 

 various species, more especially in youth, is of great impor- 

 tance. Assuming favourable conditions, the species may be 

 arranged as follows, commencing with the fastest growing 

 species : 



1. Douglas fir (Pacific variety), birch, larch, Black Italian 

 poplar, Sitka spruce, red cedar. 



2. Aspen, alder, Norway maple, sycamore, ash, lime, elm. 



3. Weymouth pine. 



4. Corsican pine. 



5. Scotch pine, Austrian pine. 



6. Sweet chestnut. 



7. Beech, oak. 



8. Hornbeam. 



