119 



even a machine, in the construction of which wood has not played 

 a part, were it only to furnish the handle, or the mould or pat- 

 tern. Even with the increased substitution of steel, concrete, 

 brick, and tile, for wood, there will always be need for all the 

 wood that can be grown in the 'United States, where the annual 

 consumption per capita is 260 cubic feet which is ten times that 

 of France. This consumption for many years has been far in 

 excess of the growth, hence the strong demands on the forests 

 for wood. 



Water, also, may well be considered as another product 

 of the forest which is of vital importance to mankind. "But the 

 intimacy of the relation of the forest to the daily life of the 

 individual now, is as nothing compared to what it will be when 

 the coal, oil, and gas are exhausted ; when our great source of 

 power and heat comes, all of it instead of a part of it, out of the 

 forest, and when the daily life of every man is intimately affect- 

 ed by the resources, revenues and utilities produced by electricity 

 derived from water flowing out of the forests." 



PROTECTION FORESTS. 



Apart from their intrinsic productive value as briefly outlined 

 above, to maintain which in perpetuity, the practice of forestry 

 is essential, the forests have an influence generally beneficial to a 

 country. They act as equalizers of the flow of streams by dim- 

 inishing in general the frequency and violence of freshets and 

 increasing the low-water flow and by preventing erosion of the 

 soil. Recent investigations in India have shown that forest 

 denudation is highly injurious to regulated stream-flow. In the 

 United States on account of forest denudation at the headwater 

 of streams it is estimated that one billion tons of the most fertile 

 soil on the most fertile land in the country goes annually into the 

 ocean. This is one* of the largest losses that the nation suffers. 



PREVENTION OF RUNOFF. 



The forest is one of the most effective means of preventing 

 erosion for it protects the soil and stores the water. The force 

 of the rain is broken by the trees, the underbrush, and the litter 

 on the ground so that it does not beat upon the soil. Much of 

 the precipitation reaches the earth by running down the twigs 

 and branches. In a heavy rain the water drips down so quietly 

 as to have practically no beating effect upon the soil. There is 

 no perceptible surface run-off until great quantities of rain have 

 fallen. Instead, the water is soaked up by the organic matter or 

 humus in the upper layers of the soil and as the rain falls it is 

 absorbed by this sponge-like ground cover, is then passed on to 

 the reservoir of mineral soil beneath and finally fed out gradual- 

 ly to the springs and streams. The surface run-off is also check- 

 ed by the mechanical obstruction offered by stumps, fallen twigs, 

 moss, and branches, and even whole trees and percolation of the 



