208 SEEDING AND PLANTING 



slow juvenile growth. Hickory, oak, and beech are usually regen- 

 erated by direct seeding. Because of the relatively small size of 

 most coniferous seeds and the slowness of early growth, direct 

 seeding is less certain to result in favorable stands. Some species, 

 however, are useful on favorable sites, more especially those such 

 as western yellow pine, white pine, and Douglas fir from which 

 the seeds can be obtained at relatively low cost. The cost of 

 the seeds of red pine and jack pine prohibits their use in direct 

 seeding. 



A high cover, if not too dense, is advantageous in direct seeding 

 provided there is little or no ground cover. The shade protects 

 the surface soil from rapid changes in moisture and temperature, 

 thus improving conditions for germination. In many' parts of 

 Europe beech is regenerated by direct seeding under oak. 



A low cover formed from a dense growth of chaparral, ferns, or 

 grass is a decided disadvantage. It not only provides a safe 

 retreat for rodents and other seed-eating animals but, as soon as 

 germination takes place, directly competes with the young seed- 

 lings. The roots of grass and of similar low vegetation draw their 

 nutrients and water supply from the surface layers of the soil, 

 and the intensity of the competition usually proves fatal to the 

 introduced plants. 



The chief advantages that result from cultivating the soil are 

 as follows: 



a. It improves the moisture conditions by permitting the pre- 

 cipitation to enter with greater freedom. 



b. It facilitates aeration, or the freedom with which air can enter. 



c. It renders the soil warmer. 



d. It enables the roots of the young seedlings to enter the soil 

 more easily, penetrate to greater depth, and thus become more 

 quickly established. 



e. It induces greater chemical activity, which results in the 

 liberation of an increased amount of available plant nutrients. 



Under no condition should direct seeding be undertaken until 

 it is reasonably certain that the seed will not be destroyed before 

 germination takes place. The aim in direct seeding should be to 

 secure a stand that is neither too open nor too dense. It should 

 be sufficiently close to form a crown cover at a reasonably early 

 date and, at the same time, give each tree the best growing space 

 to meet its demands for development. 



