184 GENERAL SUMMARY 



precocious in our climate, and late frosts take their toll of 

 the young needles. South slopes of hills encourage early 

 sprouting more than north slopes, but south slopes are 

 not so injurious to the larch as frost hollows in which young 

 larch often die outright as the result of late frosts. Next, 

 the larch is extremely sensitive to shade, and whether we 

 regard this as an alpine characteristic or not, it is the 

 feature which more than any other determines its sylvicul- 

 tural treatment. Where grown pure the larch must be 

 early and thoroughly thinned, and it is best to underplant 

 it with shade bearers. When grown in mixture the- other 

 trees should be so chosen as to allow plenty of space for 

 the larch crowns, and they should be soil-improving species, 

 to compensate for the larch's deficiency in this respect. 



The soil requirements of the larch are more physical than 

 chemical, and good aeration is the most important con- 

 sideration. The soil in which it is to be grown should have : 



(i) A deep, porous subsoil. 



(ii) A surface that does not cake, but allows at all times 

 a free interchange of gases. 



(i) Unlike the spruce the larch has a tap-root, which, 

 under favourable conditions, remains alive and penetrates 

 the subsoil to a considerable depth. In addition to this, 

 lateral roots send down ' anchor ' roots, which not only fix 

 the tree firmly in the ground, but maintain the requisite 

 water-supply during a dry period. If the subsoil is hard 

 or lacking in porosity these roots penetrate for a short 

 distance, but then languish and die, and, besides adversely 

 affecting the general health of the trees, allow the entrance 

 of the chief heart-rotting fungus, Fomes annosus. Tree 

 growth is the chief agency in promoting subsoil porosity, 

 and in old oak woods or beech woods little difficulty should 

 be experienced in this respect. The subsoil of agricultural 

 land, however, is nearly always inferior, and, where possible, 

 larch should be avoided as a first rotation on such land. 

 The roots of most coniferous crops suffer in the first rotation 

 on agricultural land, and in Germany special commissions 



