98 PLANTING 



vantages and disadvantages connected with each method. 

 But, briefly, the advantages of pure -woods are: 



(1) They are very easy to manage, and thinning opera- 



tions require least skill. 



(2) The whole crop is ready to be cut at the same period. 



(3) Trees of the same species reciprocally prune the 



branches of each other, better than is the case with 

 any mixture. 



(4) Natural regeneration of one species is more easily 



effected than that of a mixture. 



But on the other hand, pure woods are often open to 

 grave disadvantages, namely : 



(1) All thinly foliaged trees open out their canopy when 



the principal height growth has ceased, and they are 

 no longer able to preserve the fertility of the soil ; 

 rank grass and other growth will appear ; and the 

 amount of moisture available for the trees will be 

 much diminished. 



(2) The danger from particular insect and fungoid attacks 



is increased ; and, in the case of pure coniferous 

 woods, the danger from fire is greater than when 

 coniferous trees are mixed with broad-leaved trees. 1 



(3) Thinnings of some pure crops are often almost value- 



less. 



On the other hand, when mixed -woods are grown, the 

 disadvantages of pure woods are largely avoided ; and other 

 advantages comprise : 



(1) If some species not suited to the soil and locality 



have been planted, they may be removed as thinnings, 

 and other trees which are more suitable may be left 

 for the final crop. 



(2) In the case of shallow rooted trees, the danger from 



storms and gales is largely avoided if they be mixed 

 with deep-rooted trees. 



1 Pure Larch, especially if grown on flat cold land or on southern 

 aspects, is far more liable to Larch Disease than when grown on northern 

 aspects, 



