MIXED AND PURE WOODS 53 



gaps in the crop should be filled by transplants, 

 special care being taken that ash are planted in 

 any spots that are suitable, oak wherever grow- 

 ing oak seedlings indicate a fair chance of success, 

 and the rest of the wood filled up with beech 

 and sycamore. 



Experience shows that, in mixed woods of 

 larch with oak, beech, or sycamore, the larch 

 have greater vigour, resistance to wind, and 

 more freedom from disease than in pure larch 

 woods ; also that larch generally does not 

 succeed as a second crop after larch. It is 

 difficult to assign satisfactory reasons for these 

 facts. Possibly broad-leaved trees offer less 

 resistance to currents of air than larch, and if 

 this is so, their presence would be an aid to 

 ventilation of the plantation. In late growth, 

 when the trees stand somewhat apart, the 

 advantage given by the broad-leaved trees is 

 probably due to their leaves, which quickly decay 

 and so keep the soil more cool and open than it 

 would be if either covered w^ith larch leaves or 

 bare and swept by winds. Agriculture shows 

 that after successive crops of the same plants 

 the soil loses something which is essential to 

 healthy growth. In the forests of Switzerland 

 larch can grow in large pure woods and maintain 



