DRY-FARMING CONGRESS, WICHITA, 1914 



89 



that during the spring melting period the run-off of the forested area was 

 only one-half of that of the burned area. On this basis, let us see what 

 might happen to the flow of the Arkansas River at Canon City, if all of 

 the 3,060 square miles of forest area above that point were burned or 

 otherwise denuded. We should find the flow during the month of the 

 highest flow (ordinarily June), which in 1911 and 1912, amounted to 2,762 

 feet, increased to double that amount, or 5,524 second-feet. Similarly, we 

 may assume that the flow during the following three or four months would 

 be reduced by an aggregate quantity approximately equal to the amount 

 which came down in the flood, since that flood caused a deficit in the 

 storage water. Let us assume that 50 percent of this deficit must be 

 made up in July, 30 percent in August, and 10 percent each in September 

 and October. This would give us for July a flow of 890 instead of 2,249 

 second-feet, and for August 93 instead of the present 905 second-feet. 

 These figures seem impossible, but we have heard of just such things 

 occurring with small streams. Is it not obvious that the amount of land 

 which could be irrigated from the Arkansas would be reduced proportion- 

 ately, except as immense storage reservoirs might hold the flood water 

 back for late summer use? Is it not apparent that the forests of the 

 mountains themselves comprise the cheapest and best reservoir for regu- 

 lating the flow of streams? 



Furthermore, deforestation of the mountains is followed not only by 

 marked irregularity of streamflow, but also by greatly increased erosion. 

 Everywhere the two go hand in hand. The quantities of sediment and 

 coarser detritus carried by the streams greatly increased the severity of 

 floods, and, by building up the lower channels of the streams, their fre- 

 quency as well. The evil effects of erosion are even more wide-reaching 

 than this, however, and thousands of acres of valuable farm lands may be 

 rendered worthless by the deposition on them of the masses of detritus 

 brought down from above. Of all vegetative covers forests are generally 

 recognized as the most efficient in preventing the slopes from eroding and 

 the stream channels from filling with silt. 



Another great influence of forests, in connection with agricultural 

 water supply, is their effect upon the moisture of adjacent fields. This is 

 a subject which has been exhaustively studied in our own region of the 

 Midddle Western States*. In this connection we are not concerned with 

 the influence of large bodies of trees, but of more or less narrow belts, 

 or even single rows of trees, surrounding fields, which we speak of as 

 "windbreaks". The value of windbreaks of forest trees in protecting fields 

 and the mechanical and physical effects of excessive winds, has been proved 

 beyond a doubt. It has been shown that any such belt of timber, in the 

 Middle- Western farming region, pays for itself, and for the ground it 

 occupies, so long as its width does not exceed three times the height of 

 the trees. In addition to this protective value, of course, any belt of trees 

 would yield more or less material of value in the form of fenceposts, fuel, 

 and even timber for construction or lumber. 



