6 WESTERN YELLOW PINE IN ARIZONA AND NEW MEXICO. 
of 125 or 150 years, during which period its bark is dark red-brown or 
blackish, with narrow furrows, in strong contrast to the lghter, 
widely furrowed bark of mature trees. This distinction between the 
two forms, which will be followed throughout this bulletin, has also 
no basis in size, although the average yellow pine, being older, is 
necessarily larger than the average blackjack. Many blackjacks 
grown in the open, however, have a larger diameter than the average 
forest-grown yellow pine. 
SOIL AND CLIMATIC REQUIREMENTS. 
Western yellow pine is not fastidious in its soil requirements. It 
does best, of course, on deep, rich soils, yet it thrives on moist to dry 
eravelly loam, on limestone formations, on malpais or lava, in 
volcanic cinders, and in gravel. It seems to adapt itself, in fact, to 
the most impoverished sites, and saplings may be seen growing on 
dry, rocky south slopes. Trees in such situations, however, are often 
stag-headed and invite attacks from mistletoe and insects. 
The distribution of yellow pine in the Southwest therefore depends 
upon altitude, with its corresponding rainfall and temperature, rather 
than upon the composition of the soil. Table 1 gives for certain 
situations in Arizona and New Mexico of known elevation and ex- 
posure the mean annual rainfall and the character of the yellow-pine 
stand in the vicinity. 
TABLE 1.—Character of yeilow pine under different conditions of altitude, rain- 
fall, and exposure. 
SOUTHERLY EXPOSURES. 






Eleva- | Mean : 
Localities. leerrorits annual Character of yellow pine. 
* | rainfall. 
Feet. | Inches. 
Santachie pNewMexce. 22-55 7,013 14.72 | No stand. 
ID Eras pit, JNabencen aa aooeseBac 6, 907 23.87 | Good stand. 
Fort Bayard, N. Mex......... 6, 040 15.20 | No stand. 
Hort Apache Ariz. ass 5, 200 18.90 Do. 
Natural Bridge, Ariz......... 4,743 18.05 Do. 
NORTHERLY EXPOSURES. 
Cloudcroft, IN: Mex: 2. =. 22 =- 8, 650 24.39 | Scattering in mixture with Douglas fir. 
Wrumna aN eee ope eee 7,300 16.58 | Good stand. 
Fort Wingate, N. Mex......-- 6, 997 14.53 | No stand; slightly below yellow-pine type. 
(aos, NecMe xn tas ieee ee 6, 983 12.81 | Scattering stand in Taos Canyon near by. 
Walliams ieAri7 ees ees 6, 750 20.64 | Good stand at slightly lower elevation. 
Magdalena, N. Mex........--- 6,557 14.49 | No stand. 
Showlow, cAvi7 <2 f20 ase ine 6, 300 19.75 | Scattering, on edge of woodland type. 
Prescott wATiz epee 5, 320 17.40 | Scattering stand near town. 



Table 1 would seem to indicate that on southern exposures below 
7,000 feet, even 18.9 inches of rainfall does not necessarily insure the 
growth of yellow pine, but that on northern exposures above 7,000 



