Engelmann spruce (Picea engelmannii): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table. Spruces from other regions have their own pages, for example Sitka spruce and black spruce.

At a glance

Item	What the source records
Scientific name	Picea engelmannii Parry ex Engelm., pine family (PLANTS and Silvics)
Other names, Silvics	Columbian spruce, mountain spruce, white spruce, silver spruce and pino real
Native status, USDA PLANTS	Native in Canada and the lower 48 states; no Alaska status listed
Size and age, Silvics	Individual trees may exceed 101.6 cm (40 in) in diameter and 49 m (160 ft) in height; dominant trees often 250 to 450 years old, with trees 500 to 600 years old not uncommon
Green weight of the wood, NRS-38	39 lb per cubic foot, without bark

Native range and climate

The Silvics of North America handbook (Agriculture Handbook 654, Volume 1, 1990) says Engelmann spruce is widely distributed in the western United States and two provinces of Canada, from British Columbia and Alberta south through all the western states to New Mexico and Arizona. In the Pacific Northwest it grows on the east slope of the Coast Range of British Columbia and along the crest and east slope of the Cascades to northern California, as a minor component of high-elevation forests. In the Rocky Mountains it is a major component of high-elevation forests, from southwestern Alberta to northern Arizona and New Mexico. The handbook gives the climate as humid, with long, cold winters, short, cool summers and heavy snowfall, and calls it one of the highest and coldest forest environments in the western United States, with temperature extremes from below minus 45.6 degrees C (minus 50 degrees F) to above 32.2 degrees C (90 degrees F). Frost can occur in any month.

Elevation depends on latitude. Silvics gives 762 to 1,067 m (2,500 to 3,500 ft) along the Coast Range of southwestern British Columbia, 2,743 to 3,353 m (9,000 to 11,000 ft) in the Rockies of Utah, Wyoming and Colorado, and 2,896 to 3,353 m (9,500 to 11,000 ft) in New Mexico, Arizona and southern Utah, with timberline at 3,505 m (11,500 ft) in the Rockies of Utah, Wyoming and Colorado. It says spruce grows best on moderately deep, well-drained loamy sands, silts and silt and clay loams, and does not grow well on rocky glacial till, heavy clay surface soils, saturated soils or shallow, dry, coarse sands and gravels.

Forest cover

The handbook says Engelmann spruce most typically grows with subalpine fir in the Engelmann Spruce-Subalpine Fir forest cover type (Society of American Foresters Type 206), and may also occur in pure or nearly pure stands. It lists 15 other cover types where spruce is usually a minor component or grows in frost pockets, among them Lodgepole Pine, Western Larch, Grand Fir and Interior Douglas-Fir. It rates the species tolerant of shade: more so than interior Douglas-fir, western white pine, lodgepole pine, aspen, western larch and ponderosa pine, and less so than subalpine fir, grand fir, white fir and mountain hemlock.

Cones and seed

The species is monoecious. Silvics says the strobili form in late April to early May, the dark purple male flowers pendant and the scarlet female flowers erect, with the female flowers near the shoot ends in the upper crown and the male on branchlets in the lower crown. Pollen is wind carried in late May and early June at low elevations and from mid-June to early July at high elevations. The cones are 2.5 to 6.3 cm (1 to 2.5 in) long and ripen in August to early September. Open-grown trees begin bearing cones when 1.2 to 1.5 m (4 to 5 ft) tall and 15 to 40 years old, but the handbook says the most abundant crops come from healthy dominant trees 15 in or more in diameter and 150 to 250 years old. It calls the species a moderate to good seed producer, with good to bumper crops every 2 to 5 years.

Size, age and roots

Silvics calls Engelmann spruce one of the largest of the high-mountain species, with average stand diameter from 38.1 to 76.2 cm (15 to 30 in) and average dominant height from 14 to 40 m (45 to 130 ft), depending on site quality and density. It says the tree matures in about 300 years and keeps growing steadily in diameter for 300 years if given space. The root system is shallow: the weak taproot of seedlings does not persist, and where the water table is near the surface or an impervious layer lies below, most roots stay in the first 30 to 46 cm (12 to 18 in) of soil, while on deep, porous, well-drained soils the lateral roots may reach 2.4 m (8 ft) or more.

Wood

The Wood Handbook (FPL-GTR-282, 2021) says the heartwood is nearly white with a slight tinge of red, the sapwood is 2 to 5 cm (1 to 2 in) wide and often hard to tell from the heartwood, and the texture is medium to fine without a characteristic odor. It rates the wood lightweight, low in strength as a beam or post, soft, and low in stiffness, shock resistance and shrinkage, with many small knots in the lumber. It lists lumber, mine timbers, railroad crossties and poles, dimension lumber, flooring and sheathing, and calls the pulp and papermaking properties excellent. Silvics adds plywood veneer and specialty items such as violins, pianos and aircraft parts.

Wood Handbook figure	Green	At 12% moisture content
Specific gravity (Table 5-3b)	0.33	0.35
Modulus of rupture, lbf per square inch (Table 5-3b)	4,700	9,300
Side hardness, lbf (Table 5-3b)	260	390

The green weight is in the NRS-38 table, the same figure used in the log weight calculator.

Damaging agents the handbook names

Windthrow. Silvics says the species is susceptible to windthrow, especially after initial cutting in old-growth forests, and ties the tendency to shallow roots while noting that root development varies with soil and stand. It sets out windfall risk by exposure in Colorado: ridgetops, saddles and all upper south- and west-facing slopes are rated very high, and valley bottoms not parallel to the prevailing wind are rated below average.
Spruce beetle. The handbook calls Dendroctonus rufipennis the most serious insect pest of Engelmann spruce, largely restricted to mature and overmature trees. Its worst outbreak in the handbook is in Colorado from 1939 to 1951, when the beetles killed nearly 6 billion board feet of standing spruce, and it links damaging attacks to extensive windthrow and cull material left after logging.
Western spruce budworm. Named as another potentially dangerous insect on spruce and fir, held in check by parasites, predators, disease and weather, with the potential for future outbreaks always present.
Fungi and mistletoe. Wood-rotting fungi are the most common diseases, with root and butt rots and trunk rots named; spruce broom rust is common in spruce-fir forests; dwarf mistletoe (Arceuthobium microcarpum) causes heavy mortality in Arizona and New Mexico and is not found elsewhere.
Fire. Thin bark and persistent dead lower limbs make the tree susceptible to severe injury by fire, though the climate where it grows lowers fire risk.

For who takes reports of regulated pests, see reporting a pest in the United States, and pests and diseases by country sets out which ones agencies regulate.