146 A MANUAL OF FORESTRY. 



trees help also to prevent damage by water rushing 

 down the hill side. At the same time the cover of the 

 shelter-wood during the final stage is already much 

 interrupted, and not too much must be expected from it ; 

 in some cases it 'may even act injuriously, as it may 

 deprive the soil of more rain-water and dew than is pre- 

 served by the beneficial action of the crowns of the trees. 



ii. FROST.* 



As regards frost, the shelter-wood does good service 

 by reducing radiation ; it is less effective against cold 

 air currents, unless it is supplemented by a dense 

 shelter-belt or wind-break along the edges of the wood. 

 Most species are liable to be injured by frost during 

 early youth, and some require protection against it for a 

 considerable number of years. 



iii. WEEDS. 



Here again the shelter-wood acts beneficially, by 

 preventing, or at any rate retarding, the springing up of 

 weeds ; thus giving time to the new crop to increase in 

 height before it has to contend with them. 



iv. INSECTS. 



Experience has shown that damage by insects is in 

 many cases less pronounced under a shelter-wood than 

 on clear cuttings. 



v. LIGHT, t 



As regards light-requirement, most species could miss 

 the shelter-wood altogether were it not required on 



* See page 115 of Volume I. 

 f See page 116 of Volume I. 



