146 



THE FORESTER 



July, 



is also known that the value of the nat- 

 ural reservoir is in almost direct ratio to 

 tin density of growth. In no other por- 

 tion of the United States has the de- 

 pendence of the tillable lands on the 

 water supply of the mountains been 

 brought to public notice with such em- 

 phasis. 



A destructive forest fire in any of the 

 mountain ranges may greatly lessen the 

 crop over the entire area depending for 

 its water supply upon the streams origi- 

 nating in the burned district. Not only 

 will the immediate effect be noticeable, 

 but the destructive results will follow for 

 years, until the burned districts become 

 covered with vegetable growth sufficient 

 to lessen the surface flow and surface 

 washing. The new growth will cause a 

 large percentage of the rainfall to pass 

 into the soil, to be available later in a 

 more constant stream flow. 



The topography of Southern California 

 and Arizona is such that at best much of 

 the rainfall flows off in immediate floods. 

 Even during the most favorable seasons 

 the streams vary greatly in their volume 

 of flow. The mountain covering must 

 be cared for and extended ; burned areas, 

 and regions otherwise denuded, must be 

 protected from sheep, and in some places 

 even from horses and cattle. This is 

 necessary in order that growth may spring 

 up as quickly as possible, to take the 

 place of that destroyed. Wherever the 

 new growth is slow in starting from lack 

 of seed, the seeds of the common chap- 

 arral of the neighborhood should be 

 sown, and occasionally artificial reforesta- 

 tion should be undertaken. 



All expenditure of time and money in 

 improving the forest cover by reforesta- 

 tion is of little value unless provision is 

 made for a reasonable degree of security 

 against forest fires. Equal provision 

 must be made at least in the mountains 

 of Southern California and Arizona for 

 the restriction of sheep grazing, which 

 should be absolutely prohibited in the 

 forest reserves of this district. 



As a specific instance in illustration of 



the destructive effects of grazing the 

 forest reserves in Central Arizona may 

 be cited. Many of the streams which 

 flow into the Salt River have their sources 

 in these reservations. Whenever sheep 

 have been driven there in large numbers, 

 the farmers of the Salt River Valley have 

 suffered material injury from the canals 

 and laterals filling with sand and silt. 



Not only do sheep crop to the ground 

 and kill much of the smaller plant life, 

 but their sharp hoofs so cut up the soil 

 that much of it washes from the rocks, 

 causing injury to agricultural interests. 

 All of the southern mountains are 

 scantily supplied with soil. There is no 

 sod to bind to the rocks what little soil 

 there is. A scattered growth of mixed 

 vegetation constitutes the cover of a great 

 part of the mountain region. After a 

 destructive fire or excessive sheep graz- 

 ing, all of these localities become prac- 

 tically barren, and incapable of support- 

 ing, for a long period, more than a very 

 limited amount of vegetation. When 

 the scanty covering of vegetable mold 

 and soil is swept into the valleys by the 

 first rains, a half century must elapse, 

 under normal conditions, before rocks 

 have disintegrated to form a new soil, to 

 be held in place by the slow growth of fu- 

 ture vegetation. 



Some of the burned mountain districts 

 of Southern California have been so 

 ruined that little of the original soil re- 

 mains in place. In these mountains the 

 rainfall flows as it does from the roofs of 

 houses. Recent investigations have 

 shown that, in some localities, fully 

 ninety per cent of the precipitation flows 

 off as surface water. 



Having in mind the great value of for- 

 est cover to those who dwell in arid re- 

 gions, the question of the best method of 

 reforesting denuded areas is of first im- 

 portance. Artificial reforestation is ex- 

 , pensive, and in but few places is it prac- 

 ticable. This is particularly true of 

 mountain sides previously swept by fire, 

 as well as in instances w r here original 

 vegetation has been badly injured by 



