REPRODUCTION OF WESTERN YELLOW PINE. 



85 



Cinder soil: 



Dry locations where any form of 

 protective cover is absent. 





high winds, they will often require 

 the leaving of trees above the min- 

 imum for seed production ; but in such 

 cases the additional trees will be left 

 for the purpose of protection against 

 wind rather than sun. 



The cinder soils here mentioned re- 

 fer to a special condition in the vol- 

 canic cinder cone region on the east 

 edge of the Coconino National Forest. 

 Coarse black or dark red cinders cover 

 a usually clayey soil to depth ranging 

 from less than an inch to a foot or 

 more. It also happens that this region 

 receives less rainfall than the yellow 

 pine type as a whole. Pine seeds germ- 

 inate with difficulty in the cinders, 

 "because the surface layer dries out 

 rapidly under exposure to sun and 

 wind. Where the cinders are more 

 than an inch deep, seedlings occur 

 most commonly where the soil is cov- 

 ered by herbs, shrubs, or litter, or in 

 the shade of trees. The deeper cin- 

 der areas are bare of grass or other 

 herbaceous growth. Under such con- 

 ditions germination takes place only 

 in the shade of trees or shrubs or in 

 spots where leaf litter has accumu- 

 lated. Although nearly all of the 

 seedlings which start in the shade of 

 trees die, a few survive in the outer 

 edges of the shade area. Because of 

 the extremely critical condition with 

 regard to germination, the leaving of 

 trees to shade the soil is warranted in 

 the cinder region where ground cover 

 is absent. The silvicultural practice 

 previously mentioned, in which cut- 

 ting is deferred until a crop of seed- 

 lings has become established under 

 the virgin stand, is recommended for 

 cinder areas of the extreme type. 



The most common forest areas 

 answering this description are ex- 

 treme forms of cinder lands, badly 

 eroded slopes, gravel slides or other 

 sites destitute of soil. Under all of 

 these conditions cutting should be 

 greatly restricted if not entirely pro- 

 hibited. Conditions similar to the 

 above in effect may obtain on clay 

 soils where the surface has been 



