A STUDY OF PINON PINE 



F. J. PHILLIPS 

 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 pinon 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 western 

 yellow pine (Pinus ponderosa) and the scrub oaks (Quercus Gambelii 

 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 taxi/olio) . In 

 association with the junipers, it forms the distinct woodland type 

 so characteristic of New Mexico and Arizona, which in this region 

 covers a more extensive area than any other forest type, and in 

 which the pinon 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 (5400 

 to 7700 feet) on moderate to steep mountain slopes and over broad, 

 level, or sloping mesas. Small isolated specimens were found up 

 to an elevation of 2600 and 2750 (8500 and 9000 feet), while occa- 

 Botanical Gazette, vol. 48] [216 



