SNOWBREAK. 569 



escapes damage after the thinning has been effected, the better 

 it will resist should a severe snow-storm occur. 



In thinned woods, individual stems are more liable to 

 breakage, whilst in unthinned woods whole patches of poles 

 may be crushed. Biihler* has undertaken some very interest- 

 ing experiments to investigate the effects of thinning on snow- 

 break. They show that heavy thinnings are less affected by 

 snow than hght thinnings ; it is not the dominant poles with 

 regularly shaped crowns that are so much endangered by the 

 snow as the badly grown poles with lop-sided crowns, and 

 these are removed in heavy thinnings as well as dead, dying 

 and dominated poles. A heavy thinning somewhat interrupts 

 the leaf-canopy, and thus allows more snow to reach the 

 ground than in a dense pole-wood. 



h. State of the. Weather. 



The snow is the more destructive the wetter and larger 

 the flakes and the more quietly it has fallen. Small flakes 

 pass more easily between the branches of the trees, and dry 

 snow is more easily shaken off' them by the wind than damp 

 snow. During a frost, however, wood is more brittle, and 

 consequently breakage is easier. 



The greatest damage is done when a thaw sets in after a 

 fall of snow, and is followed by a frost, a fresh fall of snow 

 and a strong breeze. Such a combination of circumstances 

 will cause extensive snow-breakage in woods of all ages, 

 whether sown or planted, thinned or unthinned, forming a sad 

 picture of devastation for the forester, who sees the results of 

 his care at once nullified. 



2. Record of Damar/e done hij Snow. 



Snowbreak being of a local nature only, the occurrence of 

 serious damage in the Ilarz mountains maybe cited. ])uring 

 the sixty-six years ending with 1897, there have been nineteen 

 disastrous years of snowbreak, or one year in every four, the 

 worst of which were as follows : — 



In January and February, 1844, in Hanover, two million 



* " Schnecdiuck u. Diiioliforstungsgrad," " riactisclior Forstwirtli," 1800. 

 Nos. 3— fi. 



