TREATMENT OF SEEDING AND PLANTING SITES 191 



can be broken through only in places because of the large expense 

 involved. 1 The modern method for breaking through the pan is 

 by the use of dynamite. 



6. EXCESS OF ORGANIC MATTER 



The excess of organic matter in the soil is usualty in the form 

 of peat, dry mold, and raw humus. For the most part, peat soils 

 are now non-productive but eventually, particularly in the north- 

 ern states and alpine regions, they will form an important area 

 for forest growth. Their reclamation requires drainage, which, by 

 lowering the free ground water, permits the entrance of air and 

 the gradual elimination of the peat. Their present acid condition 

 inhibits the growth of desirable timber. This, however, can be 

 overcome after drainage by the liberal application of lime. 



Many upland areas injured by fire and covered with scanty 

 vegetation develop a dense covering of lichens and moss. When 

 these decompose over dry, sandy soil, they form dry mold that 

 is harmful to reproduction. Artificial regeneration, particularly 

 direct seeding, should not be attempted before the reclamation 

 of the land by some method of cultivation which mixes the dry 

 mold with the mineral soil. Raw humus often accumulates to 

 excess in coniferous forests, so that when the stand is felled it 

 interferes with immediate reproduction either by direct seeding or 

 by planting. It is composed of twigs, leaves, and other litter, 

 which from too much or too little moisture or the lack of adequate 

 heat have not decomposed. Raw humus rapidly disappears on 

 exposure to sunlight. A delay in artificial regeneration for a 

 year after the forest is felled will usually suffice to make the seed- 

 ing or planting possible, although in direct seeding it may be 

 necessary to precede it by working the soil. 



7. SOIL INSTABILITY 



Unstable soil must be fixed before seeding or planting is at- 

 tempted. Soil fixing relates to the treatment of unstable soil of 

 steep slopes and dunes. Moving water renders the soil on all 

 slopes more or less unstable, the degree of instability depending 

 upon the character of the precipitation and the exposure of the 

 soil. The degree of instability depends also upon the velocity of 

 the wind and the amount of binding material, such as clay and 

 humus, that is present in the soil. 



1 Heyer, Carl: Der Waldbau oder die Forstproduktenzucht. 5. Aufl., I. Bd. 

 Leipzig, 1906. 



