CHAPTER XX 



PROTECTION AGAINST AVALANCHES, LAND-SLIDES, 

 FLOODS AND SHIFTING SAND 



Avalanches. The forest needs protection against injury 

 from avalanches or snow-slides and is itself a protective agent 

 in preventing damage from avalanches to property outside the 

 forest. 



Injury from avalanches is a possibility over a small frac- 

 tion of the forest area, situated on steep mountain slopes in 

 regions of heavy snowfall and usually adjacent to timberline. 



Avalanches when once started may break down and thus 

 destroy the forest in their path. They do not start within 

 the properly managed forest but originate above timberline 

 and on cutover or burned areas. Long grass, ground cover, 

 brush and reproduction assist in preventing the start of 

 avalanches. Once started avalanches are difficult to stop, 

 hence protective measures should be directed toward pre- 

 venting their origin. 



Above timberline protective measures include the encour- 

 agement of all woody plant vegetation, the preservation of a 

 grass sod and at the most dangerous points the construction 

 of ditches, walls and fences. 



Below timberline protective measures require the main- 

 tenance of a protection forest. Munger 1 mentions four 

 requirements for treatment of such a forest. 



i. Complete fire protection. This encourages the de- 

 velopment of ground cover, underbrush and repro- 

 duction. 



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