of these species have commercial value and are 
logged.) In some cases, separate estimates were 
made for certain size and age classes of timber of a 
single species; in some, estimates were combined 
for pairs of species having similar Sa cag tea and 
structural characteristics. 
Species that usually do not attain saw-timber 
size in the Douglas-fir region include Pacific yew 
(Taxus brevifolia) and some hardwoods. 
Table 1 lists the species (27),* classes, and diam- 
eter ranges for which volume was recorded, with 
the symbols adopted for convenience in referring to 
them. As applied to Douglas-fir here and else- 
where in this report, ‘‘old growth” and “‘second 
growth” are relative terms distinguishing between 
the older timber and the younger, more rapid-grow- 
ing timber. Likewise, “large” and ‘“‘small” are used 
here as relative terms distinguishing between larger 
and smaller timber of a given type or species. 
Type Definitions and Type Mapping 
In primitive forests of the Douglas-fir region 
certain fairly definite major species associations 
and innumerable minor associations may be ob- 
served. Fire, cutting, and land settlement have 
added to the complexity of forest-cover conditions, 
and consequently to the difficulty of defining types. 
Each forest type recognized in this survey had to 
have some significance in forest management. 
Types had to be within practical limits in num- 
ber, and type definitions had to be such that types 
could be determined from office records, such as 
timber cruises, and could easily be recognized in 
the field and indicated on field maps. <A _ type 
scheme that had already been adopted by the 
Forest Service for intensive surveys partly fulfilled 
the requirements. On this foundation a scheme 
was finally evolved that stood the test of 4 years’ 
field use with few changes. 
The forest-cover and land-use types recognized in 
the forest survey of the Douglas-fir region ° follow: 
Nonforest Types 
No. Nonforest land other than agricultural, 
including (7) barren areas too rocky, deficient in 
soil, or exposed to support a cover of either trees, 
4 Italic numbers in parentheses refer to Literature Cited, 
p. 145. 
5 Numbers preceding types relate to series of types listed 
for the entire Northwest. 
TasiLe 1.—Species and diameter classes for which volume was 
recorded 
CONIFERS 
Breast- 
Name and class Symbol pelea 
range 
Douglas-fir (Pseudotsuga taxifolia): Inches 
Targeiold: erowth bas. sae oe ee eo nee DA 40+ 
Smallioldicrowth®=—-=—=- =e DB 22-40 
barge second) er owithee cee: eee ena a ees ar DC 22-40 
Smallisecond' growth seat ee eee DD 16-20 
Sitka spruce (Picea sitchensis): 
Arges sao 2 SSeS hee ae ee ee Fao ee a SA 244+ 
Soma] eee a er ee errr SB 16-24 
Engelmann spruce (P. engelmannii)_______________ ES 16-+- 
Western hemlock (Tsuga heterophylla): 
SAT On eee een ere ee ey ane RI Anos HA 20+ 
Small Ae SP ee Pa ee ate ead yn LAs 258s HB 16-20 
Mountain hemlock (7. mertensiana)_.__-_________- MH 16+ 
Western redcedar (Thuja plicata): 
Lively Ss Te eee ae see eee eee Cc 16+ 
Deads esas es eens eee een Ne KC 16+ 
Port Orford white-cedar (Chamaecyparis lawsoni- 
ana): 
Dives: 222 52 er PC 16+ 
PCa Ge Gee ea ene See ak anaes ee KPC 16+ 
Alaska yellow-cedar (C. nootkatensis) 
AW ote ae ee ae a YC 16+ 
California incense-cedar (Libocedrus decurrens) ____- IC 16+ 
Ponderosa pine (Pinus ponderosa) and Jeffrey 
pine (P. jeffreyi): 
Targe: ke: 5 ee a ee eae Ho YIN 22+- 
Small? 2 See YB 12-22 
Sugar pine (P. lambertiana) SP 12+ 
Western white pine (P. monticola) and whitebark t 
pine CP lalbicaulis =e eee Ww 16+ 
Lodgepole pine (P. contorta latifolia), shore pine 
(P. contorta), and knobcone pine (P. attenuata)__| LP 16+ 
White fir (Abies concolor) and grand fir (A. 
GTENGIS) eee Ns ele Sd TR amas ee | WE 16+ 
Noble fir (A. nobilis) and Shasta red fir (A. mag- 
TLEFECESROSEENSTS) ween ee | NF 16+ 
Pacificisilverstin (Ana ma bilis) eee ere A 16+ 
Alpine fir/CAslasiocarpa) ee sea ee ee ATS 16+ 
Western larch (Larix occidentalis) and alpine larch 
Go Slyalli) et ee ee ee er ee ec een eet ee Ay; 16+ 
Redwood (Sequoia sempervirens) _____--___---_-___- R 16+ 
BROADLEAF TREES 
Red alder (Alnus rwbra)______________- eS aeeae RA 12+ 
Oregon white oak (Quercus garryana)______________ 0o 12+ 
Canyon live oak (Q. chrysolepis)___________________]| CLO 12+ 
California black oak (Q. kelloggii)_--______________- co 12+ 
Tanoak (Lithocarpus densiflora) --__----_. ----_-__- TO 12+ 
Northern black cottonwood (Populus trichocarpa | 
hastata) and quaking aspen (P. tremuloides)______ BC 12+ 
Bigleaf maple (Acer macrophyllum)_______________- | 12+ 
Pacific madrone (Arbutus menziesii) _________- 12+ 
Oregon ash (Frazrinus oregona)_____________________ 12+ 
California laurel (Umbellularia californica) _________ 12+ 
Golden chinquapin (Castanopsis chrysophylla) 12+ 
Western paper birch (Betula papyrifera occiden- 
talis) and northwestern paper birch (B. papyri- 
er Gi SILUCOT AGL) heme ee ee ee ee Sea WPB 12+ 
