20 SEEDING AND PLANTING 



In the selection of species attention should also be given to 

 market requirements and economic utilization. Because of the 

 expense involved in artificial reproduction and the length of time 

 required to discover serious mistakes, one cannot afford to in- 

 dulge in speculation as to which untried species may or may not 

 succeed. In artificial restocking from the point of view of finan- 

 cial results one should confine himself to those species which 

 actual experience has proved beyond doubt are acceptable for the 

 object in view. 



5. Correlation Between Site Factors and Silvical 

 Requirements 



The comparison of the forest vegetation of one region with that 

 of another shows that in each locality the forest has its particular 

 mode of growth. Every kind of forest as to species and compo- 

 sition thrives best under a particular set of conditions. One set 

 of soil and climatic conditions may induce an optimum growth in 

 white pine or red pine, while it may be wholly unsuited for the 

 growth of beech or tulip. One locality, because of its special 

 characteristics, may cause a single species to form a vigorous and 

 healthy wood. The tree may be absent from a nearby locality 

 because the soil, moisture, and other site factors are different. 

 Under one set of conditions a species may be the ruling one, while 

 under another set of conditions it may become dependent. Some 

 species are always dependent, being found only in mixture with 

 others whose presence so influences local conditions that the 

 growth and maturity of the dependent species are possible. 



In New England, spruce, hemlock, beech, and chestnut are often 

 ruling species, while white ash, white elm, tulip, and birch are 

 usually dependent. In the southern states, loblolly pine, longleaf 

 pine, bald cypress, and red maple are often ruling species, while 

 chestnut, cherry, buckeye, and cottonwood are usually dependent. 

 In the Ohio valley, beech, hard maple, and oak are usually ruling 

 species, while basswood, butternut, coffee tree, black locust, 

 sycamore, and mulberry are dependent. In the Rocky Mountain 

 region, Engelmann spruce, lodgepole pine, and yellow pine are 

 usually ruling species, while oak and other hardwoods are usually 

 dependent. On the Pacific coast, Douglas fir, redwood, hemlock, 

 and white fir are usually ruling species, while incense cedar, black 

 oak, and live oak are usually dependent. 



