FOREST RESOURCES OF THE PONDEROSA PINE REGION 



Description of the Region 



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FOR the purposes of the survey, the ponder- 

 osa pine region of Oregon and Washington 

 is defined as that part east of the summit of 

 the Cascade Range (fig. 2), exclusive of Pend 

 Oreille, Stevens, and Spokane Counties in north- 

 eastern Washington, which are principally western 

 white pine type. Jackson and Josephine Counties, 

 Oreg., already inventoried as part of the Douglas- 

 fir region (7), are also excluded, although con- 

 taining extensive ponderosa pine forests. The 

 region thus defined extends 480 miles from north 

 to south and varies in width from 200 to 275 miles. 

 It includes 65.5 million acres, of which approxi- 

 mately 22.1 million acres (table 1), or one-third, 

 is forest land and 43.4 million acres is farm, graz- 

 ing, and nonforested wild land. Because the 

 Cascade Range acts as a barrier to moisture-laden 

 winds from the Pacific Ocean, extensive areas in 

 eastern Oregon and eastern Washington have in- 

 sufficient precipitation and are treeless. The 

 "dry" timber line, the elevation below which 

 forests cease to grow because of lack of moisture, 



Table 1. — Summary of forest land areas in the ponaerosa pine 

 region, 7936 







Noncommercial forest land 





State 



Commer- 

 cial 

 forest 

 land' 



With- 

 drawn 



from 

 timber 



use 2 



Chiefly 

 valuable 



for pur- 

 poses 

 other 

 than 



timber 



Total 



Total 



Oregon_ . ... _ 

 Washington 



1,000 acres 

 10, 030. 5 

 5, 818. 8 



1,000 acres 

 147.9 

 170.4 



1 ,000 acres 

 3, 906. 9 

 2, 011. 6 



1,000 acres 

 4, 054. 8 

 2, 182. 



1 ,000 acres 

 14, 085. 3 

 8, 000. 8 



Total 



15, 849. 3 



318.3 



5, 918. 5 



6, 236. 8 



22, 086. 1 



1 Land capable of producing timber of commercial quantify and qual- 

 ity, and available now or prospectively for commercial use. 



2 Commercially valuable land. 



ranges from about 1.500 feet in northern Wash- 

 ington to about 4,000 to 5,000 feet in southern 

 Oregon. The "cold" timber line, the elevation 

 at which temperature and shortness of growing- 

 season limit tree growth, ranges from about 6,000 

 feet in northern Washington to 8,000 feet in 

 southern Oregon. On the Steens Mountains 

 in southeastern Oregon the lower limit of tree 

 growth is much higher and on a large part of this 

 area the aridity is so intense and growing season 

 so short that the dry and cold timber lines meet. 



Generally speaking, the forests are confined to 

 the mountainous districts, of which there are 

 three: (1) The Cascade Range, extending the 

 length of the region from north to south, including 

 the Klamath Plateau as its southern extremity in 

 Oregon; (2) the Blue Mountains, including the 

 Wallowa Mountains in northeastern Oregon and 

 projecting a short distance into southeastern 

 Washington; and (3) the Colville Mountains, an 

 extension of the Rocky Mountains in north- 

 eastern Washington. 



The forests of this region are almost entirely 

 conifer, hardwoods seldom occurring. Ponderosa 

 pine predominates over a very large part of the 

 region and forms extensive pure stands (fig. 3). 

 Important associates are Douglas-fir, western 

 larch, white fir, lodgepole pine, sugar pine, and 

 California incense-cedar. Ponderosa pine forms 

 pure stands at the lower elevations. As elevation 

 increases other species enter the stand until the 

 pine forests give way to mixed conifer stands. In 

 the northern part of the region ponderosa pine 

 stands form a smaller proportion of the forest than 

 in the southern part. On the colder, moister, 

 upper slopes, Pacific silver fir, noble fir, Shasta red 

 fir, Engelmann spruce, alpine fir, mountain hem- 

 lock, and western white pine commonly form 



