SOUTHERN APPALACHIAN EEGION. 



133 



to dry out and die. (See PI. XLVIII h.) Even under more 

 favorable conditions these fires have destroyed the under- 

 growth, and the larger trees have been burned near their 

 roots in such a way as to cause their destruction. (See 

 PI. XL VI.) The repeated fires have frequently exter- 

 minated the grasses and other forage plants, so that instead 

 of improving the pasturage, which has often been the 

 object in starting the forest fire, the result has been, in the 

 course of years, its almost total destruction. 



This burning of the humus and the undergrowth in the causrirreguil? 

 forests always seriously affects the flow of the streams. *° 

 No one who has ever been in a forest during a heavy rain 

 storm can fail to realize this fact. In the virgin forests 

 the raindrops are caught by the underbrush and pass down- 

 ward through the humus into the less porous soil and the 

 rock fissures beneath, to reappear weeks and months later 

 in the form of numberless springs. But where this under- 

 brush and humus have been burned away, one can not fail 

 to see that during a heavy rain storm much less of the water 

 soaks directly into the soil, and the remainder flows down 

 the surface with a velocity varying with the slope, some- 

 times washing the soil into small furrows and gullies. 

 Hence, the burning of this humus decreases the storage of 

 water in the soil and causes the more rapid accumulation 

 of this water in the brooks, and results in floods in the 

 larger streams below. 



Following in the wake of the forest fire in this connec- 

 tion is the farmer who is continually clearing the moun- ^ggPfil^^P^^fl*^* 

 tain slopes for agricultural purposes. Instead of trying 

 to improve his soil in the valley and on the adjacent slopes 

 he has for 3^ears followed the policy of clearing additional 

 patches on the mountain side as rapidly as others are 

 worn out and abandoned. Each one of these hillside fields 

 must be abandoned in from three to five years, as their 

 productiveness is short lived. After the trees have been 

 girdled and the underbrush has been destroyed, such a field 

 may be planted in corn for one or two years, then in grain 

 for a year, and one or two years in gi'ass. Then it may be 

 pastured for a year or two until with increased barrenness 

 the grass gives place to weeds and the weeds to gullies. 

 (See PI. XLIX.) 



Within two or three years after these mountain-side g^^^^g'"' 

 fields have been cleared the soil loses its color, changing 

 from dark gray or black to red, as the organic matter dis- 

 appears. Meanwhile it is losing more and more its porous 



