Slope and Aspect. — Northern and Eastern Aspects. 9 



should be used as a top-dressing. In the common practice of for- 

 estry, and at present prices of labor and of timber, we can not usu- 

 ally do more than to sow or plant the species that appear to be best 

 suited to the conditions, and we can only fertilize in nurseries and 

 special plantations. It is not improbable that methods of fertiliza- 

 tion upon an extensive scale may hereafter be employed in forest 

 planting, and with profitable results. 



Of the Slope and Aspect of Surface, and ilmr Effect, upon Tree Growth. 



38. The slope of a surface is sometimes mentioned in degrees of 

 the angle that it rises above the level. It may be called a gentk slope, 

 if under 10°; smiewlwct steep, if from 10° to 20°; deep, if from 20° 

 to 34°; and very steep, if from 35° to 45° 



39. The aspect or direction of a slope is found to have a percep- 

 tible, and often a notable influence upon tree growth, and this effect 

 is greater in proportion to the extent of surface. Upon isolated 

 swells of land and small hills, it might be scarcely noticed, but ou 

 the opposite sides of mountain ranges, or in mountain valleys, it 

 may be very great. 



40. A northern aspect receives no full sunlight, or its rays fall 

 obliquely in the morning or toward evening, according to the angle 

 of elevation. The winds are colder and dryer, but in the growing 

 season generally not strong. The soil retains moisture, and the 

 growth is often rapid. The trees retain their regular shape, and the 

 wood is softer, not as strong, but generally well adapted to manu- 

 facture. As vegetation is a little delayed, the spring frosts are not 

 so apt to do harm, but from the late and imperfect hardening of the 

 new wood, the frosts of winter may do injury. As the snows lie longer 

 on these slopes, the forests are benefited by their delaying the 

 growth in the first uncertain warm days of spring, and by the moist- 

 ure that they retain. The starting of forests by seeding is more 

 easily secured on a north slope than any other, and it is only upon this 

 slope that forest-tree seeds are sown upon the damp snows in start- 

 ing mountain forests. 



41. An eastern aspect receives the sun in the cool morning hours, 

 when the temperature and light are moderate. The winds in our 

 Atlantic States are often damp, especially in winter. The soil re- 

 tains its moisture fairly. Timber grows well, and acquires medium 

 qualities that adapt it to the greatest variety of uses. 



