420 



CONSERVATION 



knows: That streams which flow from 

 a forested area rise slowly, carry little 

 sediment, and fall slowly in times of 

 flood, and throughout the year are rela- 

 tively far more uniform in their flow; 

 whereas streams which flow from de- 

 forested regions rise quickly, carry 

 heavy bodies of sediment, and sink ear- 

 ly in the season of drought to mim'mum 

 low-water stages. 



On the basis of superficial observa- 

 tion it is sometimes said that deforesta- 

 tion as it is now proceeding in the Ap- 

 palachian Mountains does not seriou.^- 

 ly affect the streams, because the forest 

 which the lumberman cuts is soon re- 

 placed by an aftergrowth. It is true 

 that the full effect of deforestation fol- 

 lows immediately upon lumbering only 

 in extreme cases, but wherever the for- 

 est and the superficial forest soil are 

 removed a beginning has been made in 

 the process of erosion which will ulti- 

 mately remove all the soil. The after- 

 growth that follows the severe cutting 

 and burning under modern lumber con- 

 ditions is a weakened growth. It never 

 covers the surface as the virgin forest 

 did; it is always traversed by freshly 

 cut gullies, and the level of channel 

 grades is sunk below the surface from 

 a few inches to ten feet or more. The 

 advantage thus given to the eroding 

 power of thousands of rills is not over- 

 come by any natural process. Man 

 alone can so direct and localize a de- 

 fense as to make it effective, and he 

 does it only at great cost. It is true 

 that under favorable conditions the soil 

 will maintain itself till the trees of the 

 aftergrowth become merchantable tim- 

 ber, and that the processes of cutting, 

 burning and partial erosion might un- 

 der the most favorable circumstances 

 be continued till several crops had been 

 cut from the surface and a half a cen- 

 tury or more had passed, but the result 

 would be deferred merely. That result 

 is to be seen in the bare mountains that 

 stretch from Spain to Asia Minor and 

 in those of northern China. 



The forests have long protected the 

 Appalachian Mountains; they were 

 growing throughout the eastern United 

 States when a great plain stretched un- 

 broken from the Atlantic to the Mis- 



issippi, and they have continued their 

 growth, though changing in species and 

 in distribution, while the earth's sur- 

 face has been raised to the heights from 

 which the mountains are being carved. 

 During the whole process the forests 

 have conserved and protected the 

 mountain slopes from washing. 



Let us pause to consider the slow 

 changes of the ages that preceded the 

 advent of man, the destroyer, or pos- 

 sibly the protector. 



On a vast plain covering the area of 

 the eastern United States and Canada 

 there grew a luxviriant forest. The 

 plain was almost continuous. 



Within the earth titanic forces gath- 

 ered gradually till their power sufficed 

 to raise the surface slowly and to ele- 

 vate the plain. Rising in a zone that 

 reaches from Canada to Alabama the 

 elevated plain became a plateau from 

 which many rivers flowed to the At- 

 lantic and Pacific. As the slopes steep- 

 ened, the waters, falling swiftly, cut 

 their channels deeply and made can- 

 yons, which widened to valleys. Gen- 

 ial climates favored vegetation, which 

 during the long, slow process of moun- 

 tain growth and valley carving never 

 was removed extensively. Woods pre- 

 vailed and held the soil, always adjust- 

 ing their growth to the very gradual 

 changes of the valley slopes. If per- 

 chance a steep was bared by a sudden 

 landslide it was in time washed clean 

 to the hard rock and became a cliff', or 

 caved and extended till vegetation 

 could take a foothold again. Thus the 

 mountains of to-day were slowly carved 

 from the upraised mass, and ever 

 through the ages the forest trees grew 

 and flourished and died, generation af- 

 ter generation, in the soil their roots 

 held" fast and enriched and deepened. 

 It was their destiny to outlive the 

 mountains, whose inert mass must 

 yield eventually to the unceasing at- 

 tacks of erosion and be worn down 

 again to a gently sloping plain, over 

 which the forest should stretch its 

 living covering. But man has come, 

 he holds the forests' destiny in his 

 hands, and his own is intimately 

 linked with theirs. 



