52 REFORESTATION ON THE NATIONAL FORESTS. 



BLACK WALNUT (Juglans nigra). 



This tree produces valuable lumber. The growth is rapid, but satisfactory 

 results could hardly be expected on any but rather good soils. The species is 

 comparatively free from attacks by insects and fungi. The nuts are produced 

 abundantly and are easily gathered and stored. It is usually advisable to plant 

 the nuts directly in the field in seed spots, because of the long taproot de- 

 veloped by the seedlings. Being an intolerant tree, it should be grown in mix- 

 ture with other hardwoods, such as red oak. Black walnut seeding should 

 be confined to the more protected situations, where the soil is deep and fresh. 

 It is native to the National Forests of Arkansas, and is apparently adapted to 

 certain parts of Washington, Oregon, and Idaho. 



CORK OAK (Quercus suber). 



Cork oak is of considerable commercial importance, especially near the 

 Mediterranean Sea in France, Spain, and Algiers. It is from this tree that all 

 the cork of commerce is made. None is produced in the United States. It can 

 be safely said, judging from its distribution in Europe and elsewhere, that cork 

 oak is adapted for planting in the United States wherever the climate meets 

 approximately the following conditions: Minimum temperature, 21 to 25 F. ; 

 maximum temperature, 104 F. ; minimum precipitation, 20 inches. 



The climate of some of the Southern States, especially Florida, Texas, and 

 portions of California, meet the above requirements. Calcareous soils are 

 believed to be favorable to the best growth of cork oak. There are a number 

 of specimens of the tree growing in the South from seed imported and dis- 

 tributed by the United States Department of Agriculture about 1860. At Chico, 

 Cal., the tree has done well. In reforestation work the acorns may be dibbled in 

 where the trees are to grow, or may be sown in a nursery and the seedlings set 

 out when 1 year old. The acorns of the best variety are difficult to secure, as 

 the cork industry is jealously guarded. Experiments indicate that the Choc- 

 tawhatchee, Ocala, Monterey, Cleveland, Santa Barbara, Angeles, Sierra, and 

 Sequoia National Forests are suitable for the production of cork oak. 



DOUGLAS FIE (Pseudotsuga taxifolia). 



Douglas fir, next to western yellow pine, has the widest range of any of the 

 important commercial trees. of the United States, and more lumber is cut from 

 it than from any other species. Its very rapid growth, ease of reproduction, 

 adaptability to a wide range of sites, and the commercial value of its wood 

 assure it a permanent place as the leading timber tree of the West and as one 

 well adapted for reforestation work. 



Silviculturally there are two distinct forms of Douglas fir, one of which 

 inhabits the regions west of the Cascades and Sierra Nevada Mountains, while 

 the other grows throughout the Rocky Mountain region. For planting, the coast 

 form is superior to the mountain form in every respect and should always be 

 used where the climate is favorable. 



Douglas fir generally bears seed abundantly every two years, and good seed 

 can be collected at reasonable cost. Broadcast or seed-spot sowing will prob- 

 ably be the best method of artificially propagating the species, but in certain 

 regions, particularly in the Rocky Mountains, planting of 1 or 2 year old nur- 

 sery stock, spaced 4 to 6 feet apart each way, is advisable. The seed must come 

 into immediate contact with the mineral soil, otherwise germination can not be 

 expected. The tree is not exacting in regard to depth or quality of the soil, 

 provided the subsoil is deep and porous and the drainage is good. 



