A STUDY OF PINON PINE 
P.n}6 PHLIELIPS 
GENERAL DISTRIBUTION 
No other tree species of the southern portion of the Rocky Moun- 
tain region presents more difficult problems in maintaining and repro- 
ducing the natural stands than does the pifion pine (Pinus edulis). 
It ranges from northern Mexico to eastern Utah, and Colorado Springs, 
Colorado. In an east-and-west direction it extends from the hills 
of western Texas to California. Along the northern and eastern 
borders of its range it is shrublike and of botanical importance only. 
In southern Colorado, Arizona, and New Mexico, it has a great eco- 
nomic and silvicultural importance, which will steadily decrease unless 
measures are taken to prevent excessive utilization. 
It is commonly found in mixture with the one-seeded juniper 
(Juniperus monosperma) in the northern part of its range and with the 
alligator juniper (Juniperus pachyphloea) and one-seeded juniper in 
the south. Throughout its distribution it is associated with weste™™ 
yellow pine (Pinus ponderosa) and the scrub oaks (Quercus Gambelit 
and Quercus acuminata), often forming with these species a transition 
belt between stands of juniper and western yellow pine. Occasionally 
it is found with stunted Douglas fir (Pseudotsuga taxifolia). In 
association with the junipers, it forms the distinct woodland type 
so characteristic of New Mexico and Arizona, which in this reg! 
covers a more extensive area than any other forest type, and 63 
which the pifion is decidedly the most important tree. It is occasion- 
ally seen in pure stands over small areas, but this is rare. 
LOCAL OCCURRENCE 
The tree thrives best at a general elevation of 1650 to 2350" (540° 
to 7700 feet) on moderate to steep mountain slopes and over road, 
level, or sloping mesas. Small isolated specimens were found UP 
to an elevation of 2600 and 2750™ (8500 and gooo feet), while occ 
Botanical Gazette, vol. 48] [2x6 
