Pollard: Conservation, the National Issue 135 



Turning now to the question of the effect of forests on floods, 

 we find the problem complicated by a number of important fac- 

 tors. The volume of water that enters the springs and tributaries 

 of rivers is dependent upon the nature and character of the soil, 

 upon the general climate of the region, and of course upon the 

 total amount of precipitation. Its movement is determined by 

 gravity, resulting from the degree of elevation and by the condi- 

 tion of the channels. In a comparatively level country, as Pro- 

 fessor Cleveland Abbe has pointed out, floods may occur in every 

 small tributary, and yet these floods may so enter the main channel 

 as to cause only a gentle rise, while in other cases in similar 

 regions the small floods may produce a deluge in the main channel, 

 entirely irrespective of the extent to which the surrounding water- 

 shed may be forested. It is probable, moreover, that rich loamy 

 soil under cultivation is almost equally as good a conserver of the 

 rainfall as the porous leaf mold of the forest floor, since the latter, 

 when saturated, is apt to part suddenly with its moisture, with a 

 disastrous flood as the result. 



We may conclude, therefore, that if all or most of our forests 

 lay upon level or gently sloping areas, lumbering operations would 

 have little eft'ect upon .the spring floods. Asa matter of fact, 

 however, we have already seen that they are now practically con- 

 fined to the slopes of mountain ranges, and here I am convinced 

 from personal observation, that their removal is attended by se- 

 rious results. The southern Alleghenies in North and South 

 Carolina afford examples of all stages of denudation. When the 

 forest is lumbered, every tree is cut down, the marketable ones 

 sent to the sawmill, the others converted into firewood. When a 

 mountainer wishes to start a farm or pasture, he cuts out the 

 small trees for fuel, and girdles the large trees. Within a year 

 or two the latter are dead, and the ground is then burned over to 

 consume the brush and reduce the stumps. In either case the 

 result is the same when the slope is steep. Heavy rains first wash 

 away the surface coating of humus and then gradually dispose 

 of the top soil, exposing the bare rock beneath, or, in a clay 



