STORMS. 537 



Uprooting of the tree with the soil attached to its roots is 

 most frequent in the case of spruce or beech. 



Breakage of crown or branches is most common in the case 

 of Scots pine, alder, ash and robinia. The forked l)ranches 

 and crown of the two latter species are frequently broken by 

 storms. In the case of oaks it is chiefly the dry branches of 

 stag- headed crowns which are blown off by storms. In the 

 Vosges, a distinction is made between silver-fir trees with a 

 U fork and those with a V fork, the latter being more liable to 

 breakage. Cankered silver-fir are very liable to breakage. 



(<;) Locality. — In Germany, forests on hills and low 

 mountain-chains are more affected by storms than those in 

 higher mountainous regions. During the ten years, 1870 — 80, 

 in the Thiiringer-Wald and the Harz, damage by storms was 

 chiefly at altitudes of between 800 and 1,800 feet ; but in 1876, 

 extended to 2,800 feet. This is because at higher altitudes 

 spruce trees are shorter in the stem than those growing lower 

 down, are also grown less crowded with low crowns in Selection 

 forests, and have thus greater powers of resistance against 

 storms than the crowded lanky stems of lower altitudes. 



The confir/uration of the ground has a marked influence on 

 the amount of damage done to forests by storms. 



Gentle westerly slopes bordering on extensive plains or 

 plateaux suffer greatly, and so do outlying hills and mountain 

 ridges ; also, narrow valleys running from the west or south- 

 west tow^ards the east or north-east. The damage is then 

 done on the north and south slopes of these valleys, which 

 the wind attacks in Hank. Every bend in the valley reduces 

 the violence of the wind. To endangered localities also belong : 

 hills at the end of narrow valleys or outliers that project into 

 them and steep slopes directly in the way of the storm. 



A storm that descends a hillside is much more dangerous 

 than one blowing up-hill. Whenever south-westerly winds 

 prevail, a storm, after crossing -a mountain ridge, must 

 descend its north-easterly slope. If the west or south-west 

 slopes of the hill are denuded of trees, or if the wind has to 

 find its way across the ridge through narrow felling-areas 

 between high woods, or by funnel-shaped ravines, the damage 

 done on the north-easterly slope will be increased, as the air 



