296 



AMERICAN FORESTRY 



"(a) Upon the consolidation of slop- 

 ing grounds by preventing the disas- 

 trous washing off of materials to the 

 bottom of the valley ; 



"(b) Upon the formation and per- 

 manency of springs, at least in im- 

 permeable ground and on slopes ; 



"(c) Upon the better regime of 

 rivers at least at the period of their 

 low-water and ordinary flows." 



Your committee prefer, however, that 

 these men should speak for themselves. 

 Mr. Keller says: "In many places and 

 especially in the Mediterranean Basin 

 and outlying districts, injurious changes 

 have occurred in the nature of the soil, 

 owing to deforestation, and in some 

 special cases owing to the formation of 

 swamps. These changes have had un- 

 fortunate consequences, among others 

 an alteration in the regimen and flow 

 of waters." 



Mr. Lafosse says : "The effect oi 

 the destruction of forests, especially of 

 'the woods on mountains, is to hurt the 

 regimen of rivers and to lessen their 

 discharge." 



Mr. Lokhtine says : "Forests form 

 a beneficent factor, acting favorably on 

 the general abundance of water in a 

 country and particularly on the supply 

 of springs and rivers ; that is why the 

 destruction of forests should be consid- 

 ered as hurtful and dangerous." 



Mr. Ponti says: "Forests are al- 

 ways effective for holding steep slopes ; 

 they are powerful auxiliaries for any 

 kind of work carried on with the ob- 

 ject of reducing the volume of material 

 which the water may carry off. * * * 

 Forests retard the flow of the rain to 

 the bed of the river and reduce its 

 volume." 



Mr. Riedel says: "Is it necessary 

 over and over again to draw attention 

 to the circumstance that the meteoric 

 waters flow from the deforested slopes 

 as from the roof of a house, while in 

 forested expanses a large proportion of 

 the moisture brought by the rain is 

 caught by the crowns of the trees, 

 partly to evaporate and partly to fall 

 slowly to the ground, that it has more 

 time than that which strikes the latter 



direct to sink into the soil and supply an 

 enduring feed to the springs?" 



Mr. Wolfschutz says : "When we 

 sum up these discussions we come to 

 the conclusion that the existence of for- 

 ests and swamps will on the whole have 

 a favorable influence on the water 

 regime." 



Mr. Lauda, who has been extensively 

 quoted in respect to certain observa- 

 tions regarding floods in the Danube 

 and Seine, said at this congress: "First, 

 precipitation, retention, and discharge 

 are connected by certain laws ; second, 

 the forest exerts an influence in any 

 case on the flow of water ; third, the re- 

 tention of the water precipitated is, in 

 a certain measure, greater in the more 

 than in the less wooded basin." 



And agam he says: "A final judg- 

 ment on the subject of the influence o± 

 forests on the regimen of streams can- 

 not be uttered, the experimental data 

 possessed so far covering only a rela- 

 tively short space of time." 



And again: "The general utility of 

 the forests is so well settled * * * as 

 a means of protecting the soil against 

 earth slides * * * in reducing the 

 amount of sediment carried by the rivers, 

 so important that these reasons alone 

 justify fully the greatest possible pro- 

 motion of forest cover." 



These conclusions are in harmony 

 with the opinions of a majority of en- 

 gineers and expert foresters who have 

 appeared personally before your com- 

 mittee and are in exact accord with 

 the views of the American Institute of 

 Electrical F-ngineers, composed of 6,300 

 members, and the American Society of 

 Civil Engineers, with a membership of 

 over 4,500, both recognized as the lead- 

 ing organizations of their kind in the 

 world. In resolutions presented by 

 them to the Agricultural Committee in 

 January, 1908, their views upon the ef- 

 fect of forests on the regularity of 

 streamflow are unequivocally set forth. 



RESOLUTION OF THE AMERICAN INSTITUTE OF 

 ELECTRICAL ENGINEERS 



Whereas the value of water powers is de- 

 termined in great measure liy regularity of 

 flow of streams, which regularity is seriously 

 impaired by the removal of forest cover at 



