288 YEARBOOK OF THE DEPARTME^^T OF AG-RICULTUKE. 



On small nonforested catchment areas in the West, and possibly 

 on large ones as well, a very large part of the heavy precipitation 

 of the rainy season flows over the surface, quickly reaches the stream, 

 and is discharged from the catchment area as flood water, much as 

 water escapes from the roof of a building. On such areas the actual 

 loss through evaporation during the dry season is probably far less 

 than from a well-wooded area, because the surface soil and streams 

 are dry and there is very little moisture left to evaporate. On such 

 denuded areas it appears that the run-ofl for the few months that the 

 streams flow is considerably larger than that for the entire year from 

 similar forested areas. Although a nonforested area may. in certain 

 instances, produce a larger run-off' than a forested one, this probably 

 never occurs except when the run-off' from the nonforested area is 

 largely flood water, and of destructive rather than constructive 

 significance. 



COXCLUSIOX. 



In conclusion, it may be said that althougii the forest may have, on 

 the whole, but little appreciable effect in increasing the rainfall and 

 the annual run-off. its economic importance m regulating the flow of 

 streams is beyond computation. The great indirect value of the forest 

 is the eff'ect which it has in preventing wind and water erosion, thus 

 allowing the soil on hills and mountains to remain where it is formed. 

 and in other ways providing an adequate absorbing medium at the 

 sources of the water courses of the country. It is the amount of water 

 that passes into the soil, not the amount of rainfall, that makes a 

 region garden or desert. 



