230 



Canadian Forestry Journal, Ma^, 1919 



BENEFICIAL EFFECTS OF FOREST COVER 



By Samuel T. Dana. 



Perhaps the most obvious relation that exists 

 between forests and water is the tendency of the 

 tree cover to check erosion. The leaves and 

 branches of the trees prevent the rain from 

 beating upon the soil at it does in the open; the 

 cover which they afford delays the melting of 

 snow in the spring; the upper layers of the 

 forest soil act as an enormous sponge that ab- 

 sorbs large quantities of water which in turn 

 are passed on to the great reservoir of mineral 

 soil underneath; and finally the surface cover 

 of stumps, fallen twigs, branches, and even 

 whole trees acts as a mechanical obstruction to 

 prevent rapid run-off. The surface run-off from 

 forest areas is less, both in total amount and in 



velocity, than that from similarly situated un- 

 forested areas. The steeper and more rugged 

 the topography, the more marked is this 

 contrast. 



In hilly country some erosion is, of course, 

 inevitable under any conditions. When the 

 soil cover of trees, underbrush, and litter is 

 kept intact, however, this is more often bene- 

 ficial than otherwise, since only the lighter soil 

 particles are washed away, to be later de- 

 posited in the more level lands below, adding 

 to their fertility. But when this protective 

 cover is interfered with, whether by fire, de- 

 structive lumbering, overgrazing, or injudicious 

 clearing of land for agriculture, the proportion 



WESTERN AUSTRALIAN PUBLIC SERVICE 



PERMANENT POSITIONS UNDER THE PUBLIC SERVICE ACT. 



Applications will be received until May 31, 1919, for the position of 

 Working Plans Officer in the State Forestry Department. 

 Salary, £504-£636. 



Applicants must be qualified foresters having a degree or diploma 

 of a forest school. 



G. W. SIMPSON. 



Public Service Commissioner. 

 Perth, Western Australia. 



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