SNOWBREAK. 



563 



snow should fall before it has lost its leaves. Hornbeam 



stands the danger better, and so do ash, maples and oak. 



It is, however, more difficult to draw up a scale of broadleaved 



trees according to their powers of 



resisting spow, as so few broadleaved 



trees form woods in mountainous 



districts. 



The lower part of stems growing on 

 mountain slopes exposed to heavy 

 snowfall curves outwards before be- 

 coming vertical owing to the pressure* 

 of the snow which accumulates behind 

 it, especially during the youth of the 

 tree. In hollow depressions on steep 

 slopes, the weight of the descending 

 snow is so great, that masses of it slide 

 down every year and crush all the 

 seedlings they meet. Such places in 

 the Himalayas are bordered by species 

 of maple and horse-chestnut which 

 apparently withstand the sliding action 

 of the snow better than conifers or 

 evergreen oaks, which are the chief 

 components of the Hitnalayan forests 

 between 7,000 and U,000 feet altitude. 



b. Pari (if Tree. 



Young trees may be bent down, by 

 snow, individually or in masses, inclu- 

 sive or exclusive of the ball of earth 

 around their roots. 



Tearing out of branches by wet snow 

 from the stem, as shown in Fig. 256, 

 is a less common form of damage, by 

 which the stem becomes almost worth- 

 less for timber, and more liable to fresh 

 breakage. If all the branches of a 

 verticil are thus torn out, the leading 

 shoot invariably dies. This form of 



II 



Fig. 256. — ]*ortioii of 

 the leadiug shoot of u 

 spruce, six branches of 

 which have been torn off 

 by snow. 



O 2 



