618 I'ROTECTION AGAINST AVALANCHES. 



sliding down of the snow, the grass should be mown so as to 

 leave a high stubble. 



(h) All shrubs, such as rhododendrons, green alder, dwarf 

 birch, etc., should be preserved carefully on steep slopes. 



(c) The forest must be maintained up to the tree-limit,- and 

 this is the most important rule. Forests which serve to 

 protect the country from avalanches are commonly found in 

 Switzerland the Tyrol, and the Austrian Alps, and must be 

 properly managed so as to secure the object in view\ 



The best species for such forests are Pinus Ccmhra, 

 P. montana, green alder, larch and spruce. The mountain- 

 pine and alder resist the snow action splendidly. Spruce 

 grows up to an altitude of (5,000 feet. Beech and sycamore form 

 useful mixtures up to 4,600 feet. The Selection system must 

 be adopted, and all gaps should beat once planted up. When 

 a new forest is being formed, sometimes sowing and sometimes 

 planting should be preferred. In stony, shallow calcareous 

 soils, pit-sowings are made under the shelter of stones, rocks, 

 dead branches stuck into the ground, or of logs fixed by stakes, 

 all of which protect against the sliding of the snow\ In places 

 where there is deeper soil, in depressions, etc., multiple- 

 planting with three and four plants should be tried. The cost 

 varies from £5 to £8 per acre. Production of wood is of 

 secondary importance in such forests, and, as a rule, only 

 dead and broken wood should be utilised, and the stumps 

 should then be left in the soil, the felling being high above 

 the ground. Thickets of young wood must be carefully 

 thinned. Neither removal of litter nor pasture, more especi- 

 ally that of the destructive goat, should be allowed, but, 

 unfortunately, in such places browsing by goats is only too 

 common, and the tree-limit is being continually lowered. 



4. Protective Works. 



Protective works consisting either of ditches, rows of wattle- 

 fences or walls should be made above and below the line 

 where avalanches begin, which is easily recognised l)y a 

 sudden change in the gradient of the slope. 



{a) Ditches. — Interrupted horizontal ditches, fi to 16 feet 



