FOKEST LANDS FOB THE PROTECTION OF WATERSHEDS. 83 



of the tributaries of the Ohio have been carved out through long ages to carry 

 in safety the average flood flow. Area for area of watershed, their cross-sections 

 are much larger than those of streams in climates of less rainfall. The normal 

 section of the Ohio at Wheeling is over 2 square feet for every square mile of 

 watershed, while that of the Kaw River at Kansas City is less than one-third 

 square foot per square mile. It is therefore wholly erroneous to conclude that 

 the streams of these mountains are more subject to over-bank freshets than 

 those of the lowlands or that the freshets themselves are more destructive. 

 Considering the conditions growing out of settlement the reverse is unquestion- 

 ably the case. ' 



There is one other consideration of prime importance in this forestry argu- 

 ment, and that is the fact that no possible development of forestry can increase 

 the present percentage of forest-covered areas. At least as much ground as is 

 now devoted to agricultural purposes must continue to be so used. The utmost 

 admissible expansion of national forests will never require a greater area than 

 is now occupied by forests and second growth or logged-off lauds, which, so far 

 as run-off and erosion are concerned, are just as effective as the virgin forest 

 itself, and more effective than will be the groomed forest of the. new regime. 

 There may be a shifting of areas devoted to forests, but possible expansion, 

 compared with the present area, is so small that its influence upon the great 

 rivers, even admitting the full force of the forestry argument, would be wholly 

 inappreciable. 



The fact just dwelt upon should make us thankful that the forestry theory as 

 to the stream flow is not correct. Whatever the value of forests we can not 

 have them everywhere, and by far the greater portions already cleared away 

 must always remain deforested. If this fact of deforestation has brought with 

 it in greater degree than of old the calamities of high and low waters, then, 

 indeed, we are in an unfortunate case. But it has not done so. Nature has 

 decreed no such penalty for the subjugation of the wilderness, and on the whole 

 these natural visitations are less frequent and less extensive than they were 

 before the white man cut away the forests. 



In summarizing below the foregoing argument, the author would be particu- 

 larly careful to guard against sweeping assertions in any of his conclusions. 

 He well understands how little the subject is capable of precise demonstration. 

 Snow, for example, does not always fall, even in the open country, under the 

 influence of the wind, or it may fall in a wet condition that keeps it from 

 drifting. Altitude comes in with its lower temperature and modifies the general 

 result. There is a vast difference between a northern and a southern exposure 

 even with the same slope and topographical conditions. Precipitation scarcely 

 ever occurs twice alike on the same watershed. The combination of flow from 

 tributaries is never the same in any two floods, and there is an endless variety 

 of conditions that must qualify our rules and make us cautious in making 

 claims in a matter of this kind. The author objects solely to the contrary 

 course pursued by many forestry advocates to the extreme claims that forests 

 exert a regulating influence upon stream flow in times of great floods or 

 extreme low water in our larger rivers. These claims stand to-day absolutely 

 uuproven. The difference _between past and present conditions is not great. 

 One influence offsets another with such nicety that the change, if there is any, 

 is hard to find. The " delicate balance " maintained by nature where man has 

 not cut away the forests is replaced by other balances equally delicate and 

 efficacious in the drainage of lands, the growing of crops, and the deposition of 

 dew. 



In the following seven propositions the author sums up the arguments pre- 

 sented in the foregoing pages: 



(1) The bed of humus and debris that develops under forest cover retains 

 precipitation during the summer season, or moderately dry periods at any time 

 of the year, more effectively than do the soil and crops of deforested areas 

 similarly situated. It acts as a reservoir moderating the run-off from showers 

 and mitigating the severity of freshets, and promotes uniformity of flow at 

 such periods. 



(2) The above action fails altogether in periods of prolonged and heavy 

 precipitation, which alone produce great general floods. At such times the 

 forest bed becomes thoroughly saturated, and water falling upon it flows off 

 as readily as from the bare soil. Moreover, the forest storage, not being under 

 control, flows out in swollen streams, and may, and often does, bring the ac- 

 cumulated waters of a series of storms in one part of the watershed upon those 

 of another which may occur several days later ; so that, not only does the forest 



