Pseudotsuga menziesii

Pinaceae -- Pine family

    Richard K. Hermann and Denis P. Lavender

    Douglas-fir (Pseudotsuga menziesii), also called red-fir,  Oregon-pine, Douglas-spruce, and piño Oregon (Spanish), is one of  the world's most important and valuable timber trees. It has been a major  component of the forests of western North America since the  mid-Pleistocene (30). Although the fossil record indicates that the native  range of Douglas-fir has never extended beyond western North America, the  species has been successfully introduced in the last 100 years into many  regions of the temperate forest zone (31). Two varieties of the species  are recognized: P. menziesii (Mirb.) Franco var. menziesii,  called coast Douglas-fir, and P. menziesii var. glauca (Beissn.)  Franco, called Rocky Mountain or blue Douglas-fir.

General: Pine Family (Pinaceae). This native, evergreen tree has a round crown when mature and a conic crown when young. It reaches up to 67 m tall and 4.4 m wide. The bark on mature trunks is dark brown, thick, and deeply furrowed. The flat leaves are 2-4 cm in length, taper to a short petiole, with two whitish bands on the lower surface. The deciduous seed cones are 5-9 cm and mature the first season. The seeds have wings that are less than 25 mm.

Two varieties of this species are currently recognized: Rocky Mountain Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco var. glauca (Beissn.) Franco and Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco var. menziesii).

For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site. This tree is common in the northern and central parts of Arizona, southward to northern Mexico, and eastward to western Texas. Douglas-fir is also widespread in mixed evergreen and mixed conifer forests in California below 2200 m. It is found in the Klamath Ranges, the outer North Coast Ranges, high Cascade Range, high Sierra Nevada, San Francisco Bay Area, Central Coast, outer South Coast Ranges, and northward to British Columbia.

The latitudinal range of Douglas-fir is the greatest of any commercial  conifer of western North America. Its native range, extending from  latitude 19° to 55° N., resembles an inverted V with uneven  sides. From the apex in central British Columbia, the shorter arm extends  south along the Pacific Coast Ranges for about 2200 km (1,367 mi) to  latitude 34° 44' N., representing the range of the typical coastal or  green variety, menziesii; the longer arm stretches along the Rocky  Mountains into the mountains of central Mexico over a distance of nearly  4500 km (2,796 mi), comprising the range of the other recognized variety,  glauca- Rocky Mountain or blue. Nearly pure stands of Douglas-fir  continue south from their northern limit on Vancouver Island through  western Washington, Oregon, and the Klamath and Coast Ranges of northern  California as far as the Santa Cruz Mountains. In the Sierra Nevada,  Douglas-fir is a common part of the mixed conifer forest as far south as  the Yosemite region. The range of Douglas-fir is fairly continuous through  northern Idaho, western Montana, and northwestern Wyoming. Several  outliers are present in Alberta and the eastern-central parts of Montana  and Wyoming, the largest being in the Bighorn Mountains of Wyoming. In  northeastern Oregon, and from southern Idaho south through the mountains  of Utah, Nevada, Colorado, New Mexico, Arizona, extreme western Texas, and  northern Mexico, the distribution becomes discontinuous.

     
- The native range of Douglas-fir.

Pseudotsuga mucronata (Raf.) Sudw.:
Mexico (Mesoamerica)
Canada (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Pseudotsuga menziesii (Mirb.) Franco:
Mexico (Mesoamerica)
China (Asia)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Tree, Evergreen, Monoecious, Habit erect, Trees without or rarely having knees, Tree with bark rough or scaly, Young shoots 3-dimensional, Buds not resinous, Leaves needle-like, Leaves alternate, Needle-like leaf margins entire (use magnification), Leaf apex acute, Leaf apex obtuse, Leaves < 5 cm long, Leaves < 10 cm long, Leaves yellow-green above, Leaves yellow-green below, Leaves blue-green, Leaves not blue-green, Scale leaf glands not ruptured, Needle-like leaves flat, Needle-like leaves not twisted, Needle-like leaf habit erect, Needle-like leaf habit drooping, Needle-like leaves per fascicle mostly 1, Needle-like leaf sheath early deciduous, Needle-like leaf sheath persistent, Twigs pubescent, Twigs not viscid, Twigs with peg-like projections or large fascicles after needles fall, Berry-like cones orange, Woody seed cones > 5 cm long, Bracts of seed cone exerted, Bracts of seed cone included, Seeds tan, Seeds brown, Seeds winged, Seeds unequally winged, Seed wings prominent, Seed wings equal to or broader than body.

Trees to 100 m tall; trunk to 4 m d.b.h. in native range; bark dark gray-brown or blackish green, smooth, with resin blisters, aging rough and scaly with deep longitudinal fissures; branchlets initially light yellow, becoming red-brown when dry, slightly pubescent. Leaves dark green adaxially, linear, 1.5-3 cm × 1-2 mm, stomatal bands 2, abaxial, white, apex obtuse or acuminate. Seed cones brown, glossy, ellipsoid-ovoid, ca. 8 × 3.5-4 cm. Seed scales ± rhombic, 2-2.5 × 2-2.5 cm, as long as or longer than wide. Bracts exserted, longer than seed scales, cusp straight or reflexed, 6-10 mm, tapering at apex, lateral lobes wide and short, denticulate at margin.

Trees to 90(--100)m; trunk to 4.4m diam.; crown narrow to broadly conic, flattened in age. Twigs slender, pubescent, becoming glabrous with age. Leaves 15--30(--40) × 1--1.5mm, yellow-green to dark or bluish green, apex obtuse to acute. Pollen cones yellow-red. Seed cones 4--10 × 3--3.5cm. Seeds 5--6mm, wing longer than seed body.

Abies menziesii Mirbel, Mem. Mus. Hist. Nat. 13: 70. 1825; Abies taxifolia Lambert (1803), not Salisbury (1796); Pinus douglasii Sabine ex D. Don; Pseudotsuga douglasii (Sabine ex D. Don) Carriere; P. taxifolia (Lambert) Britton.

Abies menziesii Mirbel, Mém. Mus. Hist. Nat. 13: 63, 70. 1825; A. mucronata Rafinesque; A. taxifolia Poiret 1805, not Desfontaines 1804; Pinus taxifolia Lambert 1803, not Salisbury 1796; Pseudotsuga douglasii (Lindley) Carrière; P. mucronata (Rafinesque) Sudworth; P. taxifolia (Lambert) Britton

The variety menziesii of Douglas-fir reaches its best growth on  well-aerated, deep soils with a pH range from 5 to 6. It will not thrive  on poorly drained or compacted soils. Soils in the coastal belt of  northern California, Oregon, and Washington originated chiefly from marine  sandstones and shales with scattered igneous intrusions. These rocks have  weathered deeply to fine-textured, well-drained soils under the mild,  humid climate of the coast. Surface soils are generally acid, high in   organic matter and total nitrogen, and low in base saturation. Soils in  the Puget Sound area and in southwestern British Columbia are almost  entirely of glacial origin. Soils farther inland within the range of the  variety menziesii are derived from a wide variety of parent  materials. These include metamorphosed sedimentary material in the  northern Cascades and igneous rocks and formations of volcanic origin in  the southern Cascades.

    Depth of soils ranges from very shallow on steep slopes and ridgetops to  deep in deposits of volcanic origin and residual and colluvial materials.  Texture varies from gravelly sands to clays. Surface soils are in general  moderately acid. Their organic matter content varies from moderate in the  Cascade Range to high in portions of the Coast Range and Olympic  Peninsula. Total nitrogen content varies considerably but is usually low  in soils of glacial origin. Great soil groups characteristic of the range  of coastal Douglas-fir include Haplohumults (Reddish Brown Lateritics) of  the order Ultisols, Dystrochrepts (Brown Lateritics), Haplumbrepts (Sols  Bruns Acides) of the order Inceptisols, Haplorthods (Western Brown Forest  soils) of the order Spodosols, Xerumbrepts (Brown Podzolic soils), and  Vitrandepts (Regosols) (63).

    Soils within the range of Rocky Mountain Douglas-fir originated also  from a considerable array of parent materials. In south-central British  Columbia, eastern Washington, and northern Idaho, soils vary from basaltic  talus to deep loess with volcanic ash to thin residual soil over granitic  or sedimentary rocks. They are mostly Vitrandepts and Xerochrepts. Parent  materials in Montana and Wyoming consist of both igneous and sedimentary  rocks, and locally of glacial moraines. Soils derived from noncalcareous  substrates are variable in texture but consistently gravelly and acidic. A  significant portion of the sedimentary rocks is limestone, which gives  rise to neutral or alkaline soils ranging in texture from gravelly loams  to gravelly silts. Limestones often weather into soils that are  excessively well drained. Soils are Cryoboralfs of the order Alfisols, and  Cryandepts and Cryochrepts of the order Inceptisols. Soils in the central  and southern Rocky Mountains are very complex. They developed from glacial  deposits, crystalline granitic rocks, conglomerates, sandstones, and, in  the Southwest, limestones. These soils are Alfisols (Gray Wooded soils),  Mollisols (Brown Forest soils), Spodosols (Brown Podzolic soils, Podzols),  and Entisols (2,46).

    Altitudinal distribution of both varieties of Douglas-fir (menziesii  and glauca) increases from north to south, reflecting the  effect of climate on distribution of the species. The principal limiting  factors are temperature in the north of the range and moisture in the  south. Consequently, Douglas-fir is found mainly on southerly slopes in  the northern part of its range, and on northerly exposures in the southern  part. At high elevations in the southern Rocky Mountains, however,  Douglas-fir grows on the sunny slopes and dry rock exposures (56).

    Generally, the variety glauca grows at considerably higher  altitudes than the coastal variety of comparable latitude. Altitudinal  limit for Douglas-fir in central British Columbia is about 760 m (2,500  ft) but rises to 1250 m (4,100 ft) on Vancouver Island. In Washington and  Oregon, the species generally occurs from sea level to 1520 m (5,000 ft),  although locally it may occur higher. In the southern Oregon Cascades and  in the Sierra Nevada, the altitudinal range is between 610 and 1830 m  (2,000 and 6,000 ft). In river valleys and canyon bottoms, the species may  occasionally occur at elevations of 240 to 270 m (800 to 900 ft). Near the  southern limit of its range in the Sierra Nevada, the species grows to  elevations of 2300 m (7,500 ft). The inland variety grows at elevations  from 550 to 2440 m (1,800 to 8,000 ft) in the northern part of its range.  In the central Rocky Mountains, Douglas-fir grows mostly at elevations  between 1830 and 2590 m (6,000 and 8,000 ft), and in the southern Rocky  Mountains, between 2440 and 2900 m (8,000 and 9,500 ft). In some  localities in southern and central Arizona, Douglas-fir may be found as  low as 1550 m (5,100 ft) in canyon bottoms. The highest elevation at which  Douglas-fir grows in the Rocky Mountains is 3260 m (10,700 ft) on the  crest of Mount Graham in southeastern Arizona.

Douglas-fir grows under a wide variety of climatic conditions (table 1).  The coastal region of the Pacific Northwest has a maritime climate  characterized by mild, wet winters and cool, relatively dry summers, a  long frost-free season, and narrow diurnal fluctuations of temperature (6°  to 8° C; 43° to 46° F). Precipitation, mostly as rain, is  concentrated in the winter months. Climate in the Cascade Range and Sierra  Nevada tends to be more severe.

    Table 1- Climatic data for five regional subdivisions of  the range of Douglas-fir (6,62)            Mean temperature    Mean precipitation                  Region  July  January  Frost-free period  Annual  Snow fall              °C  °C  days  mm  cm      Pacific Northwest                  Coastal  20 to 27  -2 to 3  195 to 260    760 to 3400  0 to 60        Cascades and                    Sierra Nevada  22 to 30  -9 to 3  80 to 180  610 to 3050  10 to 300      Rocky Mountains                  Northern  14 to 20  -7 to 3  60 to 120  560 to 1020  40 to 580        Central  14 to 21  -9 to -6  65 to 130  360 to 610    50 to 460        Southern    7 to 11  0 to 2  50 to 110  410 to 760    180 to 300          °F  °F  days  in  in      Pacific Northwest                  Coastal  68 to 81   28 to 37   195 to 260    34 to 134  0 to 24        Cascades and                    Sierra Nevada  72 to 86  15 to 28  80 to 180  24 to 120    4 to 120      Rocky Mountains                  Northern  57 to 68  19 to 28  60 to 120  22 to 40    16 to 320        Central  57 to 70  16 to 22  65 to 130  14 to 24    20 to 180        Southern  45 to 52  32 to 36  50 to 110  16 to 30    70 to 120              Altitude has a significant effect on local climate. In general,  temperature decreases and precipitation increases with increasing  elevation on both western and eastern slopes of the mountains. Winters are  colder, frost-free seasons are shorter, and diurnal fluctuations of  temperature are larger (10° to 16° C; 50° to 61° F).  Much of the precipitation is snow. In the northern Rocky Mountains,  Douglas-fir grows in a climate with a marked maritime influence. Mild  continental climate prevails in all seasons, except midsummer.  Precipitation is evenly distributed throughout the year, except for a dry  period in July and August. In the central Rocky Mountains, the climate is  continental. Winters are long and severe; summers are hot and in some  parts of the region, very dry. Annual precipitation, higher on the western  sides of the mountains, is mainly snow. Rainfall patterns for the southern  Rocky Mountains generally show low winter precipitation east of the  Continental Divide but high precipitation during the growing season. West  of the Continental Divide, the rainfall is more evenly divided between  winter and summer. Frost may occur in any month in the northern part of  the range. Length of frost-free periods, however, varies within the  central and southern Rocky Mountain regions, even at the same elevations.

Systems

• Terrestrial

Cultivated. Beijing Shi, Jiangxi (Lu Shan) [native to W Canada, Mexico, W United States]

Adaptation: Douglas-fir needs excellent drainage. In the higher elevations of the West that receive snow and in the lower foothills that have moderately cold winters and hot summers, Douglas-fir requires moderate summer watering, generally 1-4 times per month depending upon the absorption rate and water retention capacity of the soil. It does best in full or part-shade and may tolerate morning and winter sun in ocean-influenced areas of northern and central California.

If establishing the tree by seed, remove the seeds from the cones, gently rub the wings off, and soak them in water for 24 hours, drain them, and thoroughly surface-dry them. Put them in a plastic bag, without any medium, seal the bag and place them in refrigerated conditions until their chilling treatment begins. Allow three times the air space as seed space in the bag. It is best to sow the seeds in late February to early March. Expose the seeds to a chilling treatment of at least four weeks prior to sowing. After cold stratification, plant the seeds in a well-drained coarse potting mix in leach tubes that are narrow but deep with two seeds per tube. These containers should allow roots to reach the air and stop growing and be at least 6 inches deep. Fertilize the containers with a starter formulation of fertilizer with low or zero nitrogen. These containers can be kept in a greenhouse for the first 4 to 6 weeks, receiving 70-degree temperatures during the day. Keep the surface of the soil moist during the germination phase. Next, after the first set of cotyledons, water the plants with a deep, thorough soaking and let the plants dry in between watering. Thin the plants down to one per container and move the pots into a shade-house with 30 percent shade after 4 to 6 weeks. Protect the plants from wind and wildlife. During the main summer growing season use a balanced fertilizer applied to each container. At the end of the growing season, use a finisher formulation of fertilizer. Plant the plants in the ground outside in the late winter or early spring in moist soil. Conduct supplemental hand watering or irrigation if the rains are insufficient. Clear weeds in a 3 feet by 3 feet area around the plants to encourage better survival and growth rate. Make sure a protective barrier is placed around the conifers such as Vexar tubing to shield them from jack rabbits, deer, and other wildlife that may feed on the leaves, stems, and roots.

Foodplant / sap sucker
hypophyllous Adelges cooleyi sucks sap of live branch of Pseudotsuga menziesii
Remarks: season: summer

In Great Britain and/or Ireland:
Plant / epiphyte
fruitbody of Antrodia xantha grows on stump of Pseudotsuga menziesii

Foodplant / saprobe
fruitbody of Armillaria gallica is saprobic on dead wood of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / pathogen
Armillaria mellea s.l. infects and damages Pseudotsuga menziesii

Foodplant / parasite
punctiform colony of Bactrodesmium dematiaceous anamorph of Bactrodesmium obliquum var. suttonii parasitises live bark of Pseudotsuga menziesii

Foodplant / saprobe
fruitbody of Baeospora myosura is saprobic on decayed, often partly buried cone of Pseudotsuga menziesii

Foodplant / saprobe
fruitbody of Bjerkandera fumosa is saprobic on decayed wood of Pseudotsuga menziesii
Remarks: Other: uncertain
Other: minor host/prey

Plant / associate
fruitbody of Buchwaldoboletus lignicola is associated with rotting wood of Pseudotsuga menziesii
Other: major host/prey

Foodplant / saprobe
stipitate, solitary or gregarious apothecium of Ciboria rufofusca is saprobic on fallen, rotting, stromatised cone scale of Pseudotsuga menziesii

Foodplant / saprobe
Foveostroma anamorph of Dermea balsamea is saprobic on dead branch of Pseudotsuga menziesii

Foodplant / saprobe
erumpent pycnidium of Phomopsis coelomycetous anamorph of Diaporthe eres is saprobic on dead cone of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / saprobe
fruitbody of Ganoderma lucidum is saprobic on dead stump of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / saprobe
fruitbody of Gloeophyllum sepiarium is saprobic on dead, fallen, decayed log (large) of Pseudotsuga menziesii
Other: major host/prey

Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Gomphidius glutinosus is ectomycorrhizal with live root of Pseudotsuga menziesii

Foodplant / pathogen
Brunchorstia anamorph of Gremmeniella abietina infects and damages live twig of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / saprobe
fruitbody of Hemimycena lactea is saprobic on dead debris of Pseudotsuga menziesii

Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Hygrophorus lucorum is ectomycorrhizal with live root of Pseudotsuga menziesii
Remarks: Other: uncertain
Other: minor host/prey

Foodplant / saprobe
fruitbody of Hypholoma lateritium is saprobic on dead, decayed wood of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Inocybe subcarpta is ectomycorrhizal with live root of Pseudotsuga menziesii
Remarks: Other: uncertain
Other: major host/prey

Foodplant / saprobe
fruitbody of Ischnoderma benzoinum is saprobic on dead, fallen trunk (large) of Pseudotsuga menziesii

Foodplant / saprobe
apothecium of Lachnellula calyciformis is saprobic on dead twig of Pseudotsuga menziesii
Remarks: season: 12-4

Foodplant / saprobe
fruitbody of Laetiporus sulphureus is saprobic on trunk of old tree of Pseudotsuga menziesii
Other: unusual host/prey

Plant / associate
Laricobius erichsoni is associated with Pseudotsuga menziesii

Foodplant / saprobe
fruitbody of Lepiota perplexa is saprobic on soil of tree of Pseudotsuga menziesii
Other: unusual host/prey

Foodplant / sap sucker
nymph of Leptoglossus occidentalis sucks sap of unripe seed of Pseudotsuga menziesii
Remarks: season: 5-8
Other: major host/prey

Foodplant / saprobe
fruitbody of Leucogyrophana sororia is saprobic on dead, very decayed, brown rotted bark of Pseudotsuga menziesii

Plant / associate
fruitbody of Limacella delicata var. vinosorubescens is associated with Pseudotsuga menziesii
Other: unusual host/prey

Foodplant / saprobe
fruitbody of Marasmiellus ramealis is saprobic on dead, fallen, decayed brash of Pseudotsuga menziesii
Other: major host/prey

Foodplant / parasite
amphigenous, subepidermal pycnium of Melampsora laricis-populina parasitises live leaf of Pseudotsuga menziesii
Remarks: season: 5-6
Other: uncertain

Foodplant / saprobe
stromatic, in large groups perithecium of Nectria fuckeliana is saprobic on dead branch of Pseudotsuga menziesii
Remarks: season: 3-8
Other: minor host/prey

Foodplant / saprobe
in small groups, erumpent on thin stroma perithecium of Nectria pinea is saprobic on dead branch of Pseudotsuga menziesii
Remarks: season: 9-5
Other: minor host/prey

Foodplant / saprobe
erumpent, solitary or clustered apothecium of Pezicula livida is saprobic on dead, fallen cone of Pseudotsuga menziesii
Remarks: season: 1-12
Other: minor host/prey

Foodplant / saprobe
immersed, partially erumpent pycnidium of Phomopsis coelomycetous anamorph of Phacidiopycnis pseudotsugae is saprobic on dead trunk of Pseudotsuga menziesii

Foodplant / parasite
hypophyllous, superficial pseudothecium of Phaeocryptopus gaeumannii parasitises live leaf of Pseudotsuga menziesii
Remarks: season: 6-7

Foodplant / pathogen
fruitbody of Phaeolus schweinitzii infects and damages live root of mature tree of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / saprobe
fruitbody of Phanerochaete radicata is saprobic on dead, decayed wood of Pseudotsuga menziesii
Other: major host/prey

Foodplant / saprobe
fruitbody of Phellinus ferreus is saprobic on dead, fallen trunk of Pseudotsuga menziesii
Other: unusual host/prey

Foodplant / saprobe
fruitbody of Pleurocybella porrigens is saprobic on dead, decayed wood of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Porphyrellus porphyrosporus is ectomycorrhizal with live root of Pseudotsuga menziesii
Remarks: Other: uncertain
Other: unusual host/prey

Foodplant / saprobe
fruitbody of Postia placenta is saprobic on dead, decayed wood of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / saprobe
fruitbody of Postia sericeomollis is saprobic on dead, decayed trunk (large) of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / saprobe
fruitbody of Postia stiptica is saprobic on dead, decayed log (large) cut end of Pseudotsuga menziesii
Other: major host/prey

Foodplant / saprobe
fruitbody of Resinicium bicolor is saprobic on dead, decayed wood of Pseudotsuga menziesii
Other: major host/prey

Foodplant / parasite
in rows, subepidermal, opening by epidermis folding back apothecium of Rhabdocline pseudotsugae parasitises live leaf of Pseudotsuga menziesii
Remarks: season: 5-7

Foodplant / mycorrhiza / ectomycorrhiza
subhypogeous fruitbody of Rhizopogon villosulus is ectomycorrhizal with live root of Pseudotsuga menziesii
Remarks: Other: uncertain
Other: major host/prey

Foodplant / mycorrhiza / ectomycorrhiza
hypogeous fruitbody of Rhizopogon vinicolor is ectomycorrhizal with live root of Pseudotsuga menziesii
Remarks: Other: uncertain

Foodplant / saprobe
superficial, clustered, hypophyllous pycnidium of Rhizosphaera coelomycetous anamorph of Rhizosphaera kalkhoffii is saprobic on dead needle of Pseudotsuga menziesii
Remarks: season: late winter to early spring

Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Russula albonigra is ectomycorrhizal with live root of Pseudotsuga menziesii
Remarks: Other: uncertain
Other: minor host/prey

Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Russula delica is ectomycorrhizal with live root of Pseudotsuga menziesii
Remarks: Other: uncertain
Other: minor host/prey

Foodplant / saprobe
conidioma of Pycnidiella coelomycetous anamorph of Sarea resinae is saprobic on resinous exudate of Pseudotsuga menziesii
Remarks: season: 1-12
Other: minor host/prey

Foodplant / saprobe
fruitbody of Serpula himantioides is saprobic on dead, decayed wood of Pseudotsuga menziesii
Other: major host/prey

Foodplant / saprobe
conidioma of Sirococcus coelomycetous anamorph of Sirococcus conigenus is saprobic on fallen cone of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / saprobe
effuse colony of Spadicoides dematiaceous anamorph of Spadicoides atra is saprobic on dead wood of Pseudotsuga menziesii

Foodplant / saprobe
fruitbody of Sparassis crispa is saprobic on dead root of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / pathogen
erumpent pycnidium of Sphaeropsis coelomycetous anamorph of Sphaeropsis sapinea infects and damages live twig of Pseudotsuga menziesii
Remarks: season: 10-4
Other: minor host/prey

Foodplant / saprobe
immersed, becoming erumpeny conidioma of Strasseria coelomycetous anamorph of Strasseria geniculata is saprobic on dead twig of Pseudotsuga menziesii
Remarks: season: 1-5
Other: minor host/prey

Foodplant / saprobe
long-rooted fruitbody of Strobilurus esculentus is saprobic on buried, partially decayed cone of Pseudotsuga menziesii
Remarks: season: spring
Other: unusual host/prey

Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Suillus lakei is ectomycorrhizal with live root of Pseudotsuga menziesii

Plant / associate
fruitbody of Tephrocybe cessans is associated with Pseudotsuga menziesii

Foodplant / saprobe
effuse colony of Thysanophora dematiaceous anamorph of Thysanophora penicillioides is saprobic on dead, rotting, fallen needle of Pseudotsuga menziesii
Other: minor host/prey

Foodplant / saprobe
erumpent coelomycetous anamorph of Tryblidiopsis pinastri is saprobic on dead, attached twig of Pseudotsuga menziesii
Remarks: season: 1-4

Periodic recurrence of catastrophic wildfires created vast, almost pure  stands of coastal Douglas-fir throughout its range north of the Umpqua  River in Oregon. Although logging has mainly eliminated the original  old-growth forest, clearcutting combined with slash burning has helped  maintain Douglas-fir as the major component in second-growth stands. Where  regeneration of Douglas-fir was only partially successful or failed, red  alder (Alnus rubra) has become an associate of Douglas-fir or has  replaced it altogether.

    Rocky Mountain Douglas-fir grows in extensive pure stands, uneven- and  even-aged, in southern Idaho and northern Utah and in western Montana as a  broad belt between ponderosa pine and spruce-fir zones. At high elevations  or northerly latitudes, more cold-tolerant mountain hemlock (Tsuga  mertensiana), whitebark pine (Pinus albicaulis), true firs  (Abies spp.), Engelmann spruce (Picea engelmannii),  western white pine (Pinus monticola), and lodgepole pine (Pinus  contorta) gradually replace Douglas-fir. Douglas-fir yields to  ponderosa pine (P. ponderosa), incense-cedar (Libocedrus  decurrens), Oregon white oak Quercus garryana), California  black oak (Q. kelloggii), canyon live oak (Q. chrysolepis),  and interior live oak (Q. wislizeni) on droughty sites, and to  western redcedar (Thuja plicata), maples (Acer spp.),  red alder, black cottonwood (Populus trichocarpa), and other  broad-leaved species on poorly drained sites.

    Toward the fog belt of the Pacific coast, Douglas-fir gives way to Sitka  spruce (Picea sitchensis), western hemlock (Tsuga  heterophylla), and western redcedar. The variety menziesii is a major  component of four forest cover types (20): Pacific Douglas-Fir (Society of  American Foresters Type 229), Douglas-Fir-Western Hemlock (Type 230), Port  Orford-Cedar (Type 231), and Pacific Ponderosa Pine-Douglas-Fir (Type  244). It is a minor component of the following types:

    221 Red Alder 
223 Sitka Spruce 
224 Western Hemlock 
225 Western Hemlock-Sitka Spruce 
226 Coastal True Fir-Hemlock 
227 Western Redcedar-Western Hemlock 
228 Western Redcedar 
232 Redwood 
233 Oregon White Oak 
234 Douglas-Fir-Tanoak-Pacific Madrone

    The variety glauca is a principal species in three forest cover  types: Interior Douglas-Fir (Type 210), Western Larch (Type 212), and  Grand Fir (Type 213). It is a minor species in five types: Engelmann  Spruce-Subalpine Fir (Type 206), White Fir (Type 211), Western White Pine  (Type 215), Aspen (Type 217), and Lodgepole Pine (Type 218).

    Wherever Douglas-fir grows in mixture with other species, the proportion  may vary greatly, depending on aspect, elevation, kind of soil, and the  past history of an area, especially as it relates to fire. This is  particularly true of the mixed conifer stands in the southern Rocky  Mountains where Douglas-fir is associated with ponderosa pine,  southwestern white pine (Pinus strobiformis), corkbark fir (Abies  lasiocarpa var. arizonica), white fir (Abies concolor),  blue spruce (Picea pungens), Engelmann spruce, and aspen (Populus  spp.).

    The most important shrubs associated with coastal Douglas-fir (21)  through its central and northern range are vine maple (Acer  circinatum), salal (Gaultheria shallon), Pacific rhododendron  (Rhododendron macrophyllum), Oregongrape (Berberis nervosa),  red huckleberry (Vaccinium parvifolium), and salmonberry (Rubus  spectabilis). Toward the drier southern end of its range, common shrub  associates are California hazel (Corylus cornuta var. californica),  oceanspray (Holodiscus discolor), creeping snowberry (Symphoricarpos  mollis), western poison-oak (Toxicodendron diversilobum), ceanothus  (Ceanothus spp.), and manzanita (Arctostaphylos spp.).

    Principal understory species associated with variety glauca differ  within its range (3). In the northern part, they are common snowberry (Symphoricarpos  albus), white spirea (Spirea betulifolia), ninebark (Physocarpus  malvaceus), and pachistima (Pachistima myrsinites). In the  central part, they are true mountain-mahogany (Cercocarpus montanus),  squaw currant (Ribes cereum), chokeberry (Prunus  virginiana), big sagebrush (Artemisia tridentata), western  serviceberry (Amelanchier alnifolia), and bush rockspirea (Holodiscus  dumosus); in the southern part they are New Mexico locust (Robinia  neomexicana), Rocky Mountain maple (Acer glabrum), and  oceanspray (3).

From seed to maturity, Douglas-fir is subject  to serious damage from a variety of agents. Douglas-fir is host to  hundreds of fungi, but relatively few of these cause serious problems.  Various species of Pythium, Rhizoctonia, Phytophthora, Fusarium, and  Botrytis may cause significant losses of seedlings in nurseries  (58,60), whereas Rhizina undulata, shoestring root rot (Armillaria  mellea), and laminated root rot (Phellinus weirii) have caused  significant damage in plantations. In fact, the latter two fungi represent  a serious threat to management of young-growth stands of Douglas-fir,  especially west of the summit of the Cascades. Trees die or are so  weakened that they are blown over. Effective control measures are not  available. Of the many heart rot fungi (more than 300) attacking  Douglas-fir, the most damaging and widespread is red ring rot (Phellinus  pini). Knots and scars resulting from fire, lightning, and falling  trees are the main courts of infection. Losses from this heart rot far  exceed those from any other decay. Other important heart rot fungi in the  Pacific Northwest are Fomitopsis officinalis, F. cajanderi, and  Phaeolus schweinitzii (28). In the Southwest, Echinodontium  tinctorium, Fomitopsis cajanderi, and F. pinicola are  important.

    Several needle diseases occur on Douglas-fir. The most conspicuous, a  needlecast, is caused by Rhabdocline pseudotsugae. It is mainly a  disease of younger trees, reaching damaging proportions only after  prolonged periods of rain while the new needles are appearing. The  interior variety is particularly susceptible to the disease but is less  often exposed to long periods of rain during the spring growth period.

    The most damaging stem disease of Douglas-fir is Arceuthobium  douglasii. This dwarf mistletoe occurs throughout most of the range of  Douglas-fir (26).

    Over 60 species of insects are indigenous to Douglas-fir cones, but only  a few species damage a significant proportion of the seed crop. Damage by  insects is frequently more pronounced during the years of light or medium  seed crops that may follow good or heavy crops.

    The most destructive insects include: (a) the Douglas-fir seed chalcid  (Megastigmus spermotrophus), which matures in the developing seed  and gives no external sign of its presence; (b) the Douglas-fir cone moth  (Barbara colfaxiana) and the fir cone worm (Dioryctria  abietivorella) whose larvae bore indiscriminately through the  developing cones and may leave external particles of frass; and (c) the  Douglas-fir cone gall midge (Contarinia oregonensis) and cone  scale midge (C. washingtonensis), which destroy some seed but  prevent harvest of many more by causing galls that prevent normal opening  of cones. The Douglas-fir cone moth is perhaps a more serious pest in the  drier, interior portions of the Douglas-fir range and the Contarinia  spp.in the wetter regions. Any of these insects, however, may  effectively destroy a cone crop in a given location (27).

    Insects are generally not a severe problem for Douglas-fir regeneration,  although both the strawberry root weevil (Otiorhynchus oratus) and  cranberry girdler (Chrysoteuchia topiaria) may cause significant  damage to seedlings in nurseries; damage to plantations by rain beetles  (Pleocoma spp.) and weevils (Steremnius carinatus)- the  latter particularly damaging to container-grown-plants-has been reported.

    The Douglas-fir tussock moth (Orgyia pseudotsugata) and the  western spruce budworm (Choristoneura fumiferana) are the most  important insect enemies of Douglas-fir. Both insects attack trees of all  ages at periodic intervals throughout the range of interior Douglas-fir,  often resulting in severe defoliation of stands. The Douglas-fir beetle  (Dendroctonus pseudotsugae) is a destructive insect pest in  old-growth stands of coastal and interior Douglas-fir. Its impact is  diminishing, however, with the change to second-growth management and  rotations of less than 100 years (24).

    Consumption of Douglas-fir seeds by small forest mammals such as  white-footed deer mice, creeping voles, chipmunks, and shrews, and birds  such as juncos, varied thrush, blue and ruffed grouse, and song sparrows  further reduces seed quantity. A single deer mouse may devour 350  Douglas-fir seeds in a single night. Mouse populations of 7 to 12/ha (3 to  5/acre) are not uncommon. Most seedfall occurs at least 150 days before  the germination period, so this single rodent species has the capacity to  destroy the great majority of natural seedfall. Spot seeding studies in  the Western United States have clearly demonstrated that forest mammals  destroy virtually all unprotected seed.

    Browsing and clipping by hares, brush rabbits, mountain beaver, pocket  gophers, deer, and elk often injure seedlings and saplings. Recent reports  have indicated that such damage in western Oregon and Washington may  strongly affect seedling survival in many plantations (7,61). In drier  areas, domestic livestock have caused considerable damage to variety glauca  plantations by grazing and trampling seedlings. In pole-sized timber,  bears sometimes deform and even kill young trees by stripping off the bark  and cambium.

    High winds following heavy rains occasionally cause heavy losses from  blowdown in the Pacific Northwest. Heavy snow and ice storms periodically  break the tops of scattered trees in dense young stands. Crown fires, when  they occur, destroy stands of all ages. The thick bark of older  Douglas-firs, however, makes them fairly resistant to ground fires.

Except in its youth, when it is  reasonably tolerant of shade, coastal Douglas-fir is classed as  intermediate in overall shade tolerance, below most of its common  associates in tolerance to shade (42). Of these associates, ponderosa  pine, Jeffrey pine (Pinus jeffreyi), incense-cedar, noble fir (Abies  procera), and red alder are more demanding of light. In its interior  range, Douglas-fir ranks intermediate in tolerance among its associates,  being more tolerant than western larch, ponderosa pine, lodgepole pine,  southwestern white pine, and aspen (23).

    The coastal variety is a seral species, except on extremely dry sites in  southwestern Oregon and northern California. In its interior range,  Douglas-fir is both a climax and a seral species. In the northern Rocky  Mountains, it replaces ponderosa pine, lodgepole pine, and western larch  above the ponderosa pine belt, and in turn is replaced by western  redcedar, western hemlock, Engelmann spruce, grand fir, and subalpine fir  on cooler and wetter sites. In the southern Rocky Mountains, Douglas-fir  is a climax species in several habitat types of mixed conifer forest and a  seral species in the spruce-fir forests (4).

    The natural occurrence of Douglas-fir in extensive stands is mainly a  consequence of forest fires. The species' rapid growth and longevity, the  thick corky bark of its lower boles and main roots, combined with its  capacity to form adventitious roots, are the main adaptations that have  enabled Douglas-fir to survive less fire-resistant associates and to  remain a dominant element in western forests. Without fire or other  drastic disturbance, Douglas-fir would gradually be replaced throughout  much of its range by the more tolerant hemlock, cedar, and true fir.  Old-growth forests of Douglas-fir tend to show wide ranges in age  structure-rather than being even-aged- which indicates that Douglas-fir  was not established over short periods after major fires or other  disturbances (22).

    Stands of vigorous Douglas-fir can be successfully regenerated by any of  the even-aged methods. Clear cutting in combination with planting is the  most widely used method. In stands infected with dwarf mistletoe (Arceuthobium  spp.), clearcutting is the best alternative for eliminating  the disease. If clearcutting on good sites results in establishment of red  alder, Douglas-fir is at a severe disadvantage. Alder has very rapid  juvenile growth on high sites and can easily over top and suppress  Douglas-fir. If Douglas-fir is released in time, however, its subsequent  development will actually benefit from the nitrogen fixed by red alder.  Nitrogen is the only nutrient in forest soils of the Pacific Northwest  (41) and Intermountain Northwest (44) that has been shown to be limiting  to growth of Douglas-fir.

    Because of its ability to tolerate shade in the seedling stage, the  shelterwood system is a feasible alternative to clearcutting in coastal  stands (64). Shelterwood cutting has been practiced only on a limited  scale in the Pacific Northwest, however, where the large dimensions of  old-growth timber, danger of blowdown to the residual stand, and  probability of brush encroachment limit its use. In the Rocky Mountains,  shelterwood cutting has been more commonly applied and with good results  (50). Where interior Douglas-fir is climax, the true selection method can  be used. It is unsuitable for coastal Douglas-fir.

    Although Douglas-fir may be regenerated either naturally or artificially  from seed, the erratic spacing characteristic of many naturally  regenerated stands and the general lack of reliability of this system have  resulted in legislation (Forestry Practices Acts) in Washington, Oregon,  and California that virtually mandates artificial regeneration. And,  because direct seeding also produces variable results, the regeneration  system uses 2-year-old bare root seedlings, 3-year-old transplants,  year-old container-grown seedlings, or 2-year-old transplants that were  grown the first year in containers (9). Such planting stock may be  affected by agents discussed here under the heading "Damaging Agents"  or may suffer mortality from a lack of vigor occasioned by improper  production and harvest practices, from poor planting practices, and from  frost damage incurred either in nursery beds or after planting (13).

    When Douglas-fir develops in a closed stand, the lower limbs die rapidly  as they are increasingly subjected to overhead shade. Nevertheless,  natural pruning is exceedingly slow because even small dead limbs resist  decay and persist for a very long period. On the average, Douglas-fir is  not clear to a height of 5 m (17 ft) until 77 years old, and to 10 m (33  ft) until 107 years. Obviously, natural pruning will not produce clear  butt logs in rotations of less than 150 years. Artificial pruning will  greatly reduce the time required to produce clear lumber but may result in  severe grain distortion and brittle grain structure around pruning wounds  (10).

    Seedlings and saplings of Douglas-fir respond satisfactorily to release  from competing brush or overstory trees if they have not been suppressed  too severely or too long. Trees of pole and small sawtimber size in  general respond very well to thinning. Trees that have developed in a  closed stand, however, are poorly adapted to radical release, such as that  occasioned by very heavy thinning. When exposed, the long slender holes  with short crowns are highly susceptible to damage from snowbreak,  windfall, and sunscald. Sudden and drastic release of young Douglas-fir  may cause a sharp temporary reduction in height growth (57). Application  of a nitrogen fertilizer in combination with thinning gives better growth  responses in Douglas-fir than either fertilizer or thinning alone (41).

Although Douglas-fir is potentially a  deep-rooting species, its root morphology varies according to the nature  of the soil. In the absence of obstructions, Douglas-fir initially forms a  tap root that grows rapidly during the first few years. In deep soils (69  to 135 cm, 27 to 53 in), it was found that tap roots grew to about 50  percent of their final depth in 3 to 5 years, and to 90 percent in 6 to 8  years; however, boulders or bedrock close to the soil surface result in  quick proliferation of the original tap root. Platelike root systems  develop when Douglas-fir grows in shallow soils or soils with a high water  table. Main lateral branches develop during the first or second growing  season as branches of the tap root. These structural roots tend to grow  obliquely into deeper soil layers and contribute to anchoring a tree. The  majority of roots in the surface soil are long rope-like laterals of  secondary and tertiary origin. Fine roots, those less than 0.5 cm (0.2 in)  in diameter, develop mostly from smaller lateral roots and are  concentrated in the upper 20 cm (8 in) of soil (29). Fine roots have a  short life-span, ranging in general from a few days to several weeks.  Cyclic death and replacement of fine roots changes seasonally, reflecting  changes in environmental conditions (51).

    Size of the root system appears to be related to size of the crown  rather than the bole. In British Columbia, ratios of root spread to crown  width averaged 1.1 for open- and 0.9 for forest-grown Douglas-fir, but  greater lateral spread has been observed on poorly drained sand and sandy  gravel soils. The radial symmetry of root systems seems to be readily  distorted by slope, proximity to other trees, and presence of old roots.  Observations in the Pacific Northwest and the Rocky Mountains indicate  that roots of Douglas-fir extend farther downslope than upslope.

    The proportion of root biomass decreases with age and may vary from 50  percent at age 21 to less than 20 percent in stands older than 100 years  (29). Root grafting is very common in stands of Douglas-fir, often leading  to a system of interconnected roots in older stands (36).

Douglas-fir does not naturally  reproduce vegetatively. Substantial research to develop cuttings as a  regeneration procedure has demonstrated that reliable rooting of cuttings  is limited to material collected from trees less than 10 years old, or  from trees that have been subjected to repeated shearing to regenerate  material with a juvenile habit. A second major impediment to the use of  cuttings as a regeneration technique for this species is that most such  material has a period of plagiotropic growth, which may be lengthy, before  the erect habit is assumed.

    Research with tissue culture techniques has demonstrated substantial  promise, but widespread use of this technique in reforestation of the  Douglas-fir region is, at best, a future possibility.

Douglas-fir germination is epigeal. Seed  germinates in mid-March to early April in the warmer portions of the range  and as late as mid-May in the cooler areas. Seedling growth the first year  is indeterminate but relatively slow and limited generally by moisture,  which triggers initiation of dormancy in midsummer. The dormant period  normally extends from midsummer until April or May of the following year  (37). Douglas-fir can produce lammas shoots, but this habit is confined to  either the more moist portion of the range or to years with abnormally  heavy summer rainfall. This habit is probably most pronounced in the  southern Rockies, where the summer period is characterized by irregular,  heavy rainstorms. In any event, the great majority of the annual shoot  growth occurs during the initial flush. First-year seedlings on better  sites in the Pacific Northwest may develop shoots 6 to 9 cm (2.5 to 3.5  in) long. Growth in subsequent years is determinate and gradually  accelerates so that when saplings are 8 to 10 years old, terminal growth  may consistently exceed 1 m (3.3 ft) per year on the more productive  sites.

    Seedlings of the variety menziesii normally survive best when  the seed germinates on moist mineral soil, but menziesii will tolerate  a light litter layer. Seedlings do not survive well, however, on heavy  accumulations of organic debris. In contrast, seedlings of the variety  glauca are favored by a duff layer, especially in the larch  forests of northwestern Montana (53).

    First-year seedlings survive and grow best under light shade, especially  on southerly exposures, but older seedlings require full sunlight.  Particularly in the fog belt, competing vegetation such as alder, maple,  salmonberry, and thimbleberry (Rubus parviflorus) limits  Douglas-fir regeneration by creating intolerable levels of shade; plants  such as grasses, manzanita, ceanothus, and oak compete strongly for  available moisture; and plants such as bracken (Pteridium aquilinum)  and vetch (Vicia spp.) smother small seedlings with  leaves and other debris. Successful regeneration of variety menziesii  often depends on weed control in the commercial range of Douglas-fir  because many associated plant species have growth rates much greater than  that of juvenile Douglas-fir (8). For this reason, regeneration may be  more reliable after a wildfire, which destroys the reservoir of potential  competitive species, than after a harvest operation, which leaves areas  well suited to the rapid proliferation of the herbaceous and woody  competitors of Douglas-fir.

    In the Rocky Mountains, competing vegetation may promote the  establishment of variety glauca seedlings by reducing temperature stress  and may inhibit seedling growth by competing strongly for moisture. The  latter effect is most pronounced in the southern portions of glauca's  range.

    Microsites with adverse moisture and temperature conditions frequently  limit establishment of both menziesii and glauca seedlings on southerly  aspects (32). Soil surface temperatures in excess of 65° C (149°  F) are prevalent in the southern Cascade Range and Siskiyou Mountains and  are common in the Cascades even as far north as Mount Rainier. Prolonged  droughts, which may extend from May through September, are frequent in  southern Oregon and northern California, and low annual precipitation and  high evaporation stress greatly limit the distribution of glauca in the  Rocky Mountains.

    Like nearly all perennial woody plants, Douglas-fir is dependent on a  mycorrhizal relationship for efficient uptake of mineral nutrients and  water. Approximately 2,000 species of fungi have been identified as  potential symbionts with Douglas-fir, and both ectomycorrhizal and  ectendomycorrhizal structures have been observed on this species (59).  Occasionally, nursery practices result in seedlings with few mycorrhizae,  but no deficiencies in mycorrhizal infection have been reported for  natural seedlings.

    Historically, large burned or cleared areas in the range of variety  menziesii, such as those on Vancouver Island (52), have naturally seeded  into nearly pure stands of Douglas-fir. On mesic to moist sites this  process may occur over a relatively short period, perhaps 10 to 15 years.  On drier sites, such regeneration may be quite protracted and require a  hundred or more years. Stocking of harvested areas has been extremely  variable during the past 30 years, and large tracts in the drier or cooler  portions of the range are covered by brush species such as manzanita,  ceanothus, salmonberry, salal, or lower value hardwoods, such as alder,  maple, and oak.

    Regeneration of variety glauca in the Rocky Mountains has also been  variable. In general, glauca may be considered a seral species in moist  habitats and a climax component in the warmer, drier areas. Regeneration  is favored where Douglas-fir is seral, especially in northern Idaho and  western Montana where a strong maritime influence modifies the generally  continental climate that prevails in the central and southerly Rocky  Mountains. In contrast, regeneration of Douglas-fir is poor where the  species has attained climax status (49).

    From 1950 until about 1970, large areas of cutover and burned-over  forest land in the Pacific Northwest were aerially seeded. Direct seeding  suffers from the same deficiencies as natural regeneration, however; that  is, stands produced are often uneven in stocking and require interplanting  or pre-commercial thinning, and animals destroy a large proportion of the  seeds. With the advent of greatly increased forest nursery capacity,  direct seeding is much less common (13,54).

Major deterrents to natural  regeneration of Douglas-fir include limited seed supply; consumption of  seed by insects, animals, and birds; competing plant species; and  unfavorable environments. Although reports of fully stocked stands  resulting from seedfall from sources 1 to 2 km (0.6 to 1.2 mi) distant are  not rare, the great majority of Douglas-fir seeds fall within 100 m (330  ft) of a seed tree or stand edge (18).

    Data describing the quantities of seeds that may fall vary widely, but  most years are characterized by less than 2.2 kg/ha (2 lb/acre), of which  no more than 40 percent is sound. Years with poor seed crops generally  have a lower percentage of viable seeds, perhaps because the low incidence  of fruiting trees may favor a higher level of selfing (25).

Douglas-fir is monoecious; trees  commonly begin to produce strobili at 12 to 15 years of age, although  observations of younger seedlings bearing ovulate strobili have been  reported.

    Primordia of both pollen and seed cone buds are present when the  vegetative bud breaks in the spring of the year before the cone crop. But  neither can be distinguished from primordia of vegetative buds for the  first 10 weeks of their existence. By mid-June, histochemical differences  separate the pollen cone primordia, which are usually clustered near the  base of the extending shoot, from the seed cone primordia, which are borne  singly near the acropetal end of the shoot, and from the vegetative bud  primordia (5). These three primordia may be microscopically identified in  mid-July; by September, the egg-shaped pollen cone buds are easily  distinguished by the naked eye from the darker vegetative buds and the  larger seed cone buds.

    The size of the cone crop is determined by the number of primordia that  differentiate and develop into buds, not by the number formed. Poor cone  crops, then, reflect a high abortion rate of primordia the preceding year.  Large numbers of pollen or seed cone buds in the fall merely indicate the  potential for a heavy cone crop the following year. Damaging frost during  cone anthesis or depredations by insects may destroy most of the cones and  seeds before they mature (19).

    Male strobili are about 2 cm (0.8 in) long and range from yellow to deep  red. Female strobili are about 3 cm (1.2 in) long and range from deep  green to deep red (45). They have large trident bracts and are receptive  to pollination soon after emergence.

    Anthesis and pollination of variety menziesii occur during March  and April in the warmer part of the range and as late as May or early June  in the colder areas. At low and middle elevations, Douglas-fir cones  mature and seeds ripen from mid-August in southern Oregon to mid-September  in northern Washington and southern British Columbia. Mature cones are 8  to 10 cm (3 to 4 in) long. The bracts turn brown when seeds are mature  (45). Seedfall occurs soon after cone maturity with, generally, two-thirds  of the total crop on the ground by the end of October. The remaining seeds  fall during winter and spring months. In British Columbia, seedfall starts  later and lasts longer-less than half the seeds fall by late October and  more than one-third fall after March 1. In general, Douglas-fir seedfall  in the fog belt of western North America is more protracted than in the  drier areas east of the summit of the Coast Ranges.

    The phenology of flowering is similar for variety glauca; early  flowering occurs in mid-April to early May in Colorado and as late as  early May to late June in northern Idaho. Cone ripening varies from late  July at the lower elevations (about 850 m or 2,800 ft) in Montana to  mid-August in northern Idaho. Seed dispersal of glauca begins in  mid-August in central Oregon and occurs as late as mid-September at higher  elevations (about 1710 m or 5,600 ft) in Montana (45).

    Seed quality varies during the seedfall period. It is high in the fall  but declines rapidly during winter and spring. This pattern probably  reflects the fact that cone scales in the center of the cone, where the  highest quality seed are borne, open early and scales at the tip and base  of the cone, which bear generally poorly formed seeds, open late.

    Both cones and seeds vary greatly in size; the smaller seeds (about  132,000/kg or 60,000/lb) occur on trees in British Columbia and the larger  seeds (about 51,000/kg or 23,000/lb), on trees in California. Seeds of  variety glauca are slightly heavier and more triangular in shape  than seeds of menziesii. Size is determined before fertilization,  so there is no correlation between weight of seed and genetic vigor,  although seedlings germinated from heavier seeds may be slightly larger  the first few months of growth than those grown from lighter seeds.  Because the range in seed size from any one tree is relatively small,  however, fractionation of seed lots to segregate the heavier seed may  reduce the genetic variation and actually eliminate traits from certain  populations.

    Douglas-fir seed crops occur at irregular intervals- one heavy and one  medium crop every 7 years on the average; however, even during heavy seed  years, only about 25 percent of the trees produce an appreciable number of  cones (34). Trees 200 to 300 years old produce the greatest number of  cones. For example, a stand of old-growth Douglas-fir may produce 20 to 30  times the number of cones per hectare that a second-growth stand 50 to 100  years old produces.

Natural stands of coastal Douglas-fir normally  start with more than 2,500 trees per hectare (1,000/acre). Planted stands  generally have between 750 and 1,500/ha (300 and 600/acre) at the  beginning (9). Annual height increment is relatively slow the first 5  years but then begins to accelerate. Coastal Douglas-fir attains the  largest height increments between 20 and 30 years of age but retains the  ability to maintain a fairly rapid rate of height growth over a long  period. Douglas-fir in high-elevation forests of the Oregon-Washington  Cascade Range can continue height growth at a substantial rate for more  than 200 years (15). Height growth of Douglas-fir on dry sites at mid-site  indices in the Cascade Range of western Oregon is similar to that of  upper-slope Douglas-fir in the Washington and Oregon Cascade Range. At  higher site indices, however, height growth on dry sites is initially  faster but slower later in life; at lower site indices, it is initially  slower but faster later in life (40).

    On a medium site (III) at low elevations, height growth, which averages  61 cm (24 in) annually at age 30, continues at a rate of 15 cm (6 in) per  year at age 100, and 9 cm (3.6 in) at age 120 (18,39). Trees 150 to 180 cm  (60 to 72 in) in diameter and 76 m (250 ft) in height are common in  old-growth forests (22). The tallest tree on record, found near Little  Rock, WA, was 100.5 m (330 ft) tall and had a diameter of 182 cm (71.6  in). Coastal Douglas-fir is very long lived; ages in excess of 500 years  are not uncommon and some have exceeded 1,000 years. The oldest  Douglas-fir of which there is an authentic record stood about 48 km (30  mi) east of Mount Vernon, WA. It was slightly more than 1,400 years old  when cut (39).

    Information about yields of coastal Douglas-fir under intensive  management for an entire rotation is still limited. It is therefore  necessary to rely either on estimates based on yields from unmanaged  stands, or on yields from intensively managed stands in regions where  Douglas-fir has been introduced as an exotic (12), or on growth models  (16). If measured in cubic volume of wood produced, range in productivity  between the best and poorest sites is more than 250 percent. Depending on  site quality, mean annual net increments at age 50 vary from 3.7 to 13.4 m³/ha  (53 to 191 ft³/acre) in unmanaged stands (39). Estimates of gross  yields may increase these values as much as 80 percent, depending on  mensurational techniques and assumptions. Comparisons of gross yields from  unmanaged stands with those from managed stands of the same site indexes  in Europe and New Zealand suggest that yields in managed stands will be  considerably higher than would be indicated by estimates based on yields  in unmanaged stands. Presumably, managed stands of coastal Douglas-fir can  produce mean annual increments of 7 m³/ha (100 ft³/acre) on poor  sites and exceed 28 m³/ha (400 ft³/acre) on the highest sites  under rotations between 50 and 80 years (55). Although information on  productivity of Douglas-fir in terms of total biomass production is still  limited, indications are that it may reach 1000 t/ha (447 tons/acre) on  high sites (22).

    The interior variety of Douglas-fir does not attain the growth rates,  dimensions, or age of the coastal variety. Site class for Rocky Mountain  Douglas-fir is usually IV or V (site index 24 to 37 m or 80 to 120 ft at  age 100) when compared with the growth of this species in the Pacific  Northwest (1,43). On low sites, growth is sometimes so slow that trees do  not reach saw-log size before old age and decadence overtake them.  Interior Douglas-fir reaches an average height of 30 to 37 m (100 to 120  ft) with a d.b.h. between 38 and 102 cm (15 and 40 in) in 200 to 300  years. On the best sites, dominant trees may attain a height of 49 m (160  ft) and a d.b.h. of 152 cm (60 in) (23). Diameter growth becomes extremely  slow and height growth practically ceases after age 200. Interior  Douglas-fir, however, appears capable of response to release by  accelerated diameter growth at any size or age (35). The interior variety  is not as long lived as the coastal variety and rarely lives more than 400  years, although more than 700 annual rings have been counted on stumps  (23).

    Gross volume yields for Douglas-fir east of the Cascades in Oregon and  Washington range from 311 m³/ha (4,442 ft³/acre) for site index  15.2 m or 50 ft (at age 50) to 1523 m³/ha (21,759 ft³/acre) for  site index 33.5 m (110 ft) (14). In the northern Rocky Mountains,  estimates of yield capabilities of habitat types where Douglas-fir is  climax range from about 1.4 to 7 m³/ha (20 to 100 ft³/acre) per  year to more than 9.8 m³/ha (140 ft³/acre) per year in some of  the more moist habitat types where Douglas-fir is seral (46).

    Information on yields of Douglas-fir in the southern Rocky Mountain  region is scant. In New Mexico, a virgin stand of Douglas-fir (61 percent)  and associated species averaged 182 m³/ha (13,000 fbm/acre).  Occasionally, stands yield as high as 840 m³/ha (60,000 fbm/acre).  Annual growth rates from 2.0 to 3.9 m³/ha (140 to 280 fbm/acre) after  partial cutting have been reported in New Mexico (17).

The genus Pseudotsuga includes two species (P. menziesii  and P. macrocarpa) indigenous to North America and five  species native to Asia. All except P. menziesii have a karyotype  of 2N=24, the number of chromosomes characteristic of Pinaceae. But the  Douglas-fir karyotype is 2N=26, a probable reason for the general failure  of hybridization trials with this species (56).

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 4
Specimens with Barcodes: 20
Species With Barcodes: 1

Year Assessed

• Needs updating

Assessor/s

Reviewer/s

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values.

These species are introduced in Switzerland.

Available from most nurseries specializing in native plants within its range. Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”

Douglas-fir is grown as a Christmas tree on rotations ranging from 4 to  7 years. Trees are sheared each year to obtain a pyramid-shaped crown.  Attempts to grow Douglas-fir as a Christmas tree in North America outside  its native range have failed. Coastal Douglas-fir is usually killed by  frost, and the interior variety suffers too much from the needle cast  disease Phaeocryptopus gaeumanni.

Ethnobotanic: Douglas-fir needles were made into a tea and drank by Isleta Puebloans in New Mexico to cure rheumatism. Douglas-fir resin was used by the Shasta in northern California to poultice cuts and the Yuki along the California coast used a decoction from spring buds to treat venereal diseases. The Sinkyone of California made Douglas-fir bark tea which eased colds and stomach ailments. The Kayenta Navaho of Arizona used the tree to treat stomach disease and headaches, although what part of the plant was used is not known. Also, historically the Kayenta Navajo ground part of tree with a certain rock and mixed it with corn seeds to insure a good crop. The Pueblo people used the wood to construction dwellings while the twigs were worn on various parts of dancers' costumes. Prayer sticks made of Douglas-fir wood were excavated from archeological sites in New Mexico dating back to the Anasazi. The White Mountain Apache used the pitch of this conifer as gum and applied it to water jugs to make them watertight. Douglas-fir roots were used in California Indian basketry.

Commercial: The tree is one of the world's most important and valuable timber trees and historically it was used by Westerners for telephone poles and railway ties among many other uses. Today Douglas-fir is also grown for Christmas trees.

Wildlife: The winged seeds are eaten by western squirrels, the red tree mouse, and the dusky-foot woodrat. The foliage and twigs are browsed by antelope, mule and white-tailed deer, elk, and mountain sheep. The staminate cones and needles of Douglas-fir provide a significant winter food of the blue grouse.