Pure and Mixed Woods 41 



(3) The mixture of broad-leaved trees with conifers, lessens the 

 danger of " snow-break" of the latter. 



(4) " Storm-firm " species shelter the weaker species from wind. 



(5) The species may be selected suitable to the varying nature 

 of the soil (see Mixture by groups, below). 



(6) By admixture with shade-bearers, light-demanding trees 

 may be grown without diminishing the soil fertility, and the annual 

 increment of timber is maintained to the very end of the rotation. 



(7) Any species not adapted to the locality, or attacked by 

 insects and fungi, may be removed in the thinnings. 



Mixed woods may be formed by planting each species in groups 



mixture by groups ; or they may be formed by planting according 



to a definite plan previously decided upon, when single specimens of 



one species are placed alternately with single specimens of another 



mixture by single trees. 



(i) Mixture by groups. 



This is the usual method employed where the conditions 

 of soil, elevation, etc., vary throughout the planting area. The 

 groups may be composed either of one species of tree only, or of 

 two or more species. Each group may be regarded as a small inde- 

 pendent wood, the soil on which it is growing being of a more or 

 less similar character, so that previous remarks on pure and mixed 

 woods will apply to each of the units or groups composing the area 



Fig. 10 represents a section through an imaginary planting area, 

 and will serve to illustrate the main points. 



LARCH 



Fig. 10. 

 Mixture by groups. 



