H 

WESTERN YELLOW PINE IN ARIZONA AND NEW MEXICO.’ 
PURPOSE OF THE STUDY. 
Western yellow pine is to the Southwest what white pine is to the 
Northeast, or longleaf pine to the Southeast. The commercial for- 
ests of Arizona and New Mexico are three-fourths western yellow 
pine, which furnishes by far the greater part of the lumber used 
locally as well as that shipped to outside markets. 
To describe the characteristics of the species and to explain the 
methods of management applied to it on the National Forests of the 
Southwest, in the hope that they may be applied as well, wherever 
possible, by private owners, is the chief purpose of this bulletin. It 
should serve also to assist Forest officers in their regular work, and to 
indicate opportunities for the purchase of Government stumpage in 
the National Forests of Arizona and New Mexico. 
THE TREE. 
FORMS IN THE SOUTHWEST. 
The western yellow pine (Pinus ponderosa Laws) of the South- 
west, sometimes called bull pine, scrub pine, and infrequently white 
pine, is the same species of tree as the yellow pine of the Pacific 
slope. In Arizona and New Mexico it is, in general, a smaller, 
knottier tree, with a larger and wider crown than in California, 
Oregon, and Washington, the result of a different situation and 
climate.? 
Lumbermen and others distinguish two forms of the tree within 
the region, which they term, respectively, blackjack and yellow pine. 
The difference, however, is one of age and not of kind. Blackjack is 
merely the form which yellow pine assumes before it reaches the age 


1 Many of the figures and other data contained in this bulletin are the results of investi- 
gations by Messrs. G. A. Pearson, A. B. Recknagel, J. H. Allison, A. E. Cahoon, R. McMil- 
ate vets sO. Ds hagnee, He Ie Rerry: He B. Burrell, PR: PB. Pitchlyn; and He M- 
Curren, of the Forest Service, to whom the author desires to acknowledge his indebtedness. 
° In Forrest Service Bulletin 17, ‘““A Check List of Forest Trees of the United States,” a 
separate species of yellow pine, Pinus ponderosa scopulorum, was noted for portions of 
the Rocky Mountain region. It is now the judgment of Mr. George B. Sudworth, author 
of the Check List, that whatever differences exist between this form and that designated 
as Pinus’ ponderosa are due solely to differences in site and climate and not to any 
inherent difference in the trees themselves. 
D 

