CHAP, vii.] Formation of Mixed Woods 145 



lopping, topping, or even cutting out the other species of trees 

 threatening to suppress it. 



3. Shade-bearing (thickly-foliaged) species can be intermixed 

 with light- demanding (thinly-foliaged) species^ when the latter 

 are of more rapid grmuth in height, or when they are afforded 

 some advantage as to age or height, If, however, the shade- 

 bearing species is to be expected to develop vigorously, instead 

 of being suppressed during the youthful period of growth, it 

 must form the principal or ruling species numerically. 



4. Light-demanding species should not be permanently associated 

 together as timber crops. When the slower-growing species is 

 at the same time relatively the more capable of bearing shade 

 (e. g. Austrian Pine and Larch, Austrian Pine and Scots Pine), 

 exception to this rule can be made : 



(a) On very good soil not exposed to deterioration under 

 the light canopy of the thinly-foliaged species. Under such 

 conditions mixed growth of Alders and Ash, Oak and Elm, Oak 

 and Maples, &c., are not at all injudicious. 



(b) On very poor (sandy) soil, principally given up to 

 conifers, where of broad-leaved trees the Birch alone is 

 content to grow. 



Except on soils and situations where the Scots Pine shows 

 a decided tendency towards a fuller degree of shade-bearing 

 capacity than usual, a mixture of this species and Larch is not 

 at all advisable, although very often made in Britain (see 

 P- 155)- 



5. The subordinate species should be introduced individually 

 and not in patches or groups. Here, again, however, exceptions 

 may be made : 



(a) When the quality of the soil is variable, so that patches 

 here and there are specially suited for any one particular 

 class of tree (e. g. Spruce on shallow, stony soil ; Ash and 

 Alder on damp, wet spots ; Pines on dry patches). 



L 



