STUDY SOIL CONDITIONS 67 



be lacking, frost may destroy seedlings when it is too late to await natural 

 regeneration longer. "It is rare," says Jolyet, "without question, when 

 the conditions are such that any production of acorns or nuts is absolutely 

 impossible; it is, on the other hand, quite common to find this production 

 insufficient." 



To await natural regeneration xmder these conditions is, therefore, 

 often poor forestry; particularly with virgin stands which have not been 

 under intensive forest management, it is often best to aid nature. In 

 many German forests, it is argued that natural regeneration at best is 

 difficult and uncertain and requires more time and consequently a longer 

 rotation; so why not plant or sow at once and be done with it? In 

 France, as already explained, the conditions are more favorable. In the 

 Landes natural regeneration is almost certain; in the silver fir reasonably 

 certain; in the spruce or Scotch pine quite possible of attainment; in 

 aleppo pine attainable; with beech usually certain, as with the oak, under 

 favorable conditions. In mixture with beech the regeneration of the oak 

 is often more difficult because it cannot compete with the more shade- 

 enduring species. 



Study SoU Conditions. — It is, therefore, vital to thoroughly under- 

 stand the properties, constitution, and influences of the forest soil upon 

 the final results attained. Like agricultural soil the forest soil ^ is mineral 

 and organic. But the forest soil is more complex and more difficult to 

 keep in proper condition; moreover, conditions are constantly changing 

 so that what are normal soil conditions at the beginning of the regenera- 

 tion period should gradually change as the canopy is opened up. Forest 

 soil has (1) a dead litter of leaves, twigs, bark; (2) a humus or decayed 

 litter; (3) a vegetable soil or mixture of humus with the mineral soil; (4) 

 a mineral soil coming from the decomposed rock, and (5) the base rock 

 itself. It takes years to get a normal forest soil (that may be ruined by 

 over-exposure or fire), while the agricultural soil can be acquired arti- 

 ficially by introducing the necessary elements that may be lacking. Of 

 these ingredients, in forest soils, humus is the most important. True 

 forest humus is beneficial; on the contrary, acid humus is harmful and 

 prevents or hinders regeneration. Acid humus, infrequent in French 

 forests, may be due to a number of causes — insufficient heat, too much 

 moisture, drought, or steriUty. In everyday practice the forester is 

 troubled more by the physical texture of the soil and with the htter and 

 vegetable cover than by the chemical composition or the presence or 

 absence of chemical ingredients. A soil baked by the sun or packed by 

 grazing usually prevents regeneration, as does a cover of dry leaves, 

 grass, sod, or weed growth. For example, a growth of heather under 



2 Traits Pratique de Sylviculture, Antoine Jolyet, Bailli6re et Fils, Paris, pp. 298-358. 



