Table 6. — Area and average volume per acre, and total volume of saw-limber types in eastern Washington ' by forest-survey unit, 1936 



Chelan-Colville unit Yakima River unit 



i > pe definition ■ and No. 



Woodland, spattered ponde- 



rosa pine (5)2) ----. 



Ponderosa pine: 

 Large (20) 



Pure, large (20$ 



Small (21) 

 Ponderosa pine mixture, large 

 (27) 



Summary pine types. . 

 Douglas-fir: 



Large old growth (6)... 



Small old growth (7) . 



Large second growth (8) 



Large poles (9A) 



\\ astern redcedar: 



Large (17) 



Poles (19A). 



Fir-mountain hemlock, large 



(23) 



1'pper-slope mixture, large 



(27$ 



White fir, large (29) 



Lodgepole pine, large (25) . 

 Hardwoods, large (3lJ4)- 



summary all types. 



1,000 

 acres 

 275.8 



406.7 

 661.5 

 323.5 



233.9 



1,901.4 



153.0 

 65.4 

 93.5 



2.3 



.1 



69.0 



493.0 



.5 



9.8 



2.9 



2. 790. 9 



\ olumi per acre 



Ponde- 

 rosa 



pine 



M board 

 feet 

 0.9 



5.0 

 7.2 

 1.9 



2.2 



4.3 



All 



species 



M board 



feet 

 1. 1 



7.6 

 7.9 

 2.1 



6.6 



10.5 

 9.2 

 4.4 



20.5 



5.8 



20.3 



8.3 

 20.6 



4.2 

 7.0 



Area 



1,000 



acres 



49. 1 



205.0 

 481.8 

 207. 6 



1,083.1 



.9 

 143. 1 

 64.1 

 20.4 



1.0 



192.2 



265. 7 

 3.2 

 17.3 

 8.5 



1, 799. 5 



Volume per acre 



Ponde- 

 rosa 

 pine 



M board 

 feet 

 1.3 



7.7 

 9.5 

 3.1 



4.0 



All 

 species 



M board 

 feet 

 1.3 



11.4 

 10. 2 

 3.2 



10.8 



17.7 

 17.5 

 14.5 

 3.7 



13.3 



14.2 



11.8 

 13.0 

 2.4 

 3.4 



10.6 



North Blue Mountain 

 unit 



Area 



1,000 



acres 



9.2 



27.8 



36. 7 



5.0 



15.7 



91.4 



62.8 

 10. 1 



167.7 



Volume per acre 



Ponde- 

 rosa 

 pine 



M hoard 

 feet 

 1.0 



3.7 

 6.7 

 1.3 



All 



species 



M hoard 

 feet 

 1.0 



6.1 

 7.0 

 1.3 



6.8 

 5.8 



6.1 



Total eastern Washington 



Area 



1,000 

 acres 

 334.1 



639.5 



1, 180.0 



536.1 



389.2 



3, 078. 9 



296. 1 

 129.5 

 113.9 



3.3 



.1 



261.2 



821.5 

 13.8 

 27.1 

 11.8 



4, 758. 1 



Volume per acre 



Ponde- 

 rosa 

 pine 



A/ board 

 feet 

 1.0 



5.8 

 8.1 

 2.4 



2.8 



5.2 



All 



species 



M board 

 feet 

 1.1 



2.5 

 8.1 



17.7 

 13.9 

 11.8 

 4.3 



18.4 

 5.8 



15.8 



9.3 



8.0 

 3.1 

 4.6 



8.2 



Total volume 3 



Ponde- 

 rosa 

 pine 



Million 

 board 

 feet 

 334.1 



3, 709. 1 

 9, 558. 

 1, 286. 6 



1,089.8 



15, 977. 6 



All 

 species 



Million 

 board 

 feet 

 367.5 



5, 627. 6 

 10, 384. 

 1, 340. 3 



3,152.5 



20. 871. 9 



15.9 

 4, 115. 8 



1, 528. 1 



60.7 

 .6 



4, 127. 



7, 640. 



110.4 

 84.0 

 54.3 



39, 098. 5 



1 Exclusive of Spokane unit. 



' For description of types, see p. 4. 



3 The difference between total volumes in this table and table 10 is accounted for by volume in nonsaw-timber types. Since average volume per acre 

 values are rounded off to nearest 100 board feet, the sum of unit total volumes computed by applying volume per acre to area will not exactly equal regional 

 totals 



moist locations within the range of ponderosa 

 pine (fig. 8), well scattered throughout the region. 



Sugar pine and sugar pine-mixture types 20A 

 and 20B are confined to southern Oregon and are 

 comparatively unimportant. 



Different forms of partial cutting are widely 

 practiced in ponderosa pine stands. Determina- 

 tion of the proper system of management, par- 

 ticularly selection of trees to be cut, requires 

 detailed knowledge of the composition of loggable 

 stands. Of first importance is the distribution by 

 diameter classes of saw-timber volume in types 

 20 and 20 %, to which practically all logging in 

 these stands is confined (figs. 9, 10, and 11). 



In formulating management plans, some indica- 

 tion of stand structure or percentage of volume by 

 maturity and vigor class is needed. In figure 12, 

 presenting such a distribution of saw-timber vol- 



ume in the principal ponderosa pine types for 

 eastern Washington and eastern Oregon, the three 

 classes shown — immature, thrifty-mature, and 

 mature-overmature — approximate those employed 

 by Meyer (77) and represent a grouping of the 

 ponderosa pine tree classes defined by Dunning (5). 

 Briefly, the first class consists of trees less than 150 

 years old (Dunning classes 1, 2, and 6); the second 

 of trees 150 to 300 years old, but of moderate to 

 good vigor (Dunning class 3); all other trees 

 (Dunning classes 4, 5, and 7) are grouped in the 

 third class, which is composed predominantly of 

 trees comparatively poor in vigor and beyond the 

 age of most rapid growth. 4 The striking prepon- 



4 Obviously more detailed structure analyses are needed 

 for framing specific management plans. Since completion 

 of the forest-survey field work, the tree classification by 

 F. P. Keen (8) has been commonly used for this purpose in 

 this region. 



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