{The native range of Picea engelmannii}

Picea engelmannifiParry ex Engelm

Picea engelmannifiParry ex Engelm

Picea engelmannii Parry ex Engelm.

Engelmann spruce

Pinaceae — Pine household

Robert R. Alexander and Wayne D. Shepperd

Engelmann spruce is among the seven species of spruce indigenous to the
United States (62). Different frequent names are Columbian spruce, mountain
spruce, white spruce, silver spruce, and pino actual.

Habitat

Native Vary

Engelmann spruce is broadly distributed within the western United States and
two provinces in Canada (61). Its vary extends from British Columbia and
Alberta, Canada, south by way of all western states to New Mexico and
Arizona.

Within the Pacific Northwest, Engelmann spruce grows alongside the east slope of
the Coast Vary from west central British Columbia, south alongside the crest
and east slope of the Cascades by way of Washington and Oregon to northern
California (6,13,20). It’s a minor part of those high-elevation
forests.

Engelmann spruce is a significant part of the high-elevation Rocky
Mountain forests, rising within the Rocky Mountains of southwestern Alberta,
south by way of the excessive mountains of jap Washington and Oregon, Idaho,
and western Montana to western and central Wyoming, and within the excessive
mountains of southern Wyoming, Colorado, Utah, jap Nevada, New Mexico,
and northern Arizona (6,13,20).

{The native range of Picea engelmannii}
– The native vary of Engelmann spruce.

Local weather

Engelmann spruce grows in a damp local weather with lengthy, chilly winters and
brief, cool summers. It occupies one of many highest and coldest forest
environments within the western United States, characterised by heavy snowfall
and temperature extremes of greater than -45.6° C (-50° F) to above
32.2° C (90° F). Climatic information for 4 subregions of the United
States inside the species vary are given in desk 1 (23,42,65,100).

Desk 1- Climatological information for 4 regional
subdivisions inside the vary of Engelmann spruce

Common temperature Frost every interval
Location Annual July January Annual precip. Annual Snowfall

°C °F °C °F °C °F cm in cm in days
Pacific Northwest 2 35 10-13 50-55 -9 to -7 15-20 152-406 60-160 1015+ 400+ 45-90
U.S. Rocky Mountains
   Northern¹ -1 to 2 30-35 4-13 45-55 -12 to -7 10-20 61-114 24-45+ 635+ 250+ *30-60
   Central² -1 to 2 30-35 10-13 50-55 -12 to -9 10-15 61-140 24-55 381-889+ 150-350+ *30-60
   Southern³ 2 35 10-16 50-60 -9 to -7 15-20 61-89+ 24-35+ 508 200+ *30-75

¹Includes the
Rocky Mountains of Montana and Idaho and related mouintains of
jap Washington and Oregon.

²Includes the Rocky Mountians of Wyoming and Colorado and
related mountains of Utah.

³Includes the Rocky Mountains and related ranges of New
Mexico and Arizona and the plateaus of southern Utah.

*Frost might happen any month of the 12 months.

The vary of imply annual temperatures is slim contemplating the large
distribution of the species. Common annual temperatures are close to
freezing, and frost can happen any month of the 12 months. Common precipitation
exceeds 61 cm (24 in) yearly, with solely reasonable or no seasonal
deficiency. Summer season is the driest season within the Cascades and Rocky
Mountains west of the Continental Divide south to southwestern Colorado.
The mountains east of the divide, in southwestern Colorado, and in New
Mexico and Arizona, obtain appreciable summer time rainfall, whereas winter
snowfall will be gentle (23,48,64,100). Winds are predominantly from the
west and southwest and will be extremely damaging to Engelmann spruce
(13,20).

Soils and Topography

Info on soils the place Engelmann spruce grows is restricted. Within the
Pacific Coast area, soil father or mother supplies are blended and different. Nation
bedrock consists of a wide range of sedimentary, igneous, and metamorphic
rock. The commonest of the good soil teams are Cryorthods (Podzolic
soils), Haplumbrepts (western Brown forest soils), Haplorthods (Brown
Podzolic soils), Hapludalfs (Grey-Brown Podzolic soils), and Haploxerults
and Haplohumults (Reddish-Brown Lateritic soils); these nice soil teams
developed from deep glacial and lacustrine deposits, deep residual
materials weathered in place from nation rock, and volcanic lava and ash.
Xerochrepts (Regosolic soils), developed from shallow residual materials,
are additionally widespread. Xeropsamments (Regosolic soils) and Haplaquolls
(Humic Gley soils) are the principal soils derived from alluvium. On the
east aspect of the Cascade crest, soils are largely Haploxeralfs (Non-Calcic
Brown soils) and Haploxerolls (Chestnut soils) (39,103).

Within the Rocky Mountain subalpine zone, soil supplies fluctuate based on
the character of the bedrock from which they originated. Crystalline
granite rock predominates, however conglomerates, shales, sandstones, basalts,
and andesites generally happen. Glacial deposits and stream alluvial followers
are additionally frequent alongside valley bottoms. Of the good soils group, Cryorthods
(Podzolic Soils) and Haplorthods (Brown Podzolic Soils) happen extensively
on all features. Cryochrepts (Thick Chilly Soils) happen extensively on the
drier features. Aquods (Floor-water Podzolic Soils) are discovered within the
poorly drained areas. Cryoboralfs (Grey-Wooded Soils) are discovered the place
timber stands are -less dense and father or mother materials finer textured.
Haploborolls (Brown Forest Soils) happen principally within the decrease subalpine zone
alongside stream terraces and aspect slopes. Lithics (Lithosolic Soils) happen
wherever bedrock is close to the floor. Aquepts (Lavatory Soils) and Haplaquepts
(Humic Gley Soils) happen extensively in poorly drained higher stream
valleys (48,103).

Whatever the father or mother supplies, spruce grows finest on reasonably
deep, effectively drained, loamy sands and silts, and silt and clay loam soils
developed from a wide range of volcanic and sedimentary rock. Good development
is also made on glacial and alluvial soils developed from a variety of
father or mother supplies, the place an accessible water desk is extra vital than
bodily properties of the soil. It doesn’t develop effectively on rocky glacial
until, heavy clay floor soils, saturated soils, or on shallow, dry
coarse-textured sands and gravels developed primarily from granitic and
schistic rock or course sandstones and conglomerates (13,23).

Alongside the east slope of the Coast Vary and inside valleys of
southwestern British Columbia, Engelmann spruce grows at 762 to 1067 m
(2,500 to three,500 ft). Farther south within the Cascade Mountains of Washington
and Oregon, it typically grows at 1219 to 1829 m (4,000 to six,000 ft), however
it might be discovered at 2438 m (8,000 ft) on sheltered slopes and at 610 m
(2,000 ft) in chilly pockets alongside streams and valley bottoms. In northern
California, spruce grows at 1219 to 1524 m (4,000 to five,000 ft) (16,98).

South of the Peace River Plateau within the Canadian Mountains of British
Columbia and Alberta, Engelmann spruce grows at 762 to 1829 m (2,500 to
6,000 ft); within the Rocky Mountains of Idaho and Montana and within the adjoining
mountains of jap Washington and Oregon, at 610 to 2743 m (2,000 to
9,000 ft). However above 1829 to 2286 m (6,000 to 7,500 ft), it’s a minor
part of the stand, and under 1524 m (5,000 ft) it’s confined to
moist, low slopes and chilly valley bottoms (20).

Engelmann spruce is discovered at 2743 to 3353 m (9,000 to 11,000 ft) within the
Rocky Mountains of Utah, Wyoming, and Colorado, however it might prolong as low
as 2438 m (8,000 ft) alongside chilly stream bottoms and to timberline at 3505 m
(11,500 ft). Within the Rocky Mountains of New Mexico and Arizona and on the
plateaus of southern Utah, it grows at 2896 to 3353 m (9,500 to 11,000
ft), however it might develop as little as 2438 m (8,000 ft) and as excessive as 3658 m
(12,000 ft) (13,20).

Related Forest Cowl

Engelmann spruce most sometimes grows along with subalpine fir (Abies
lasiocarpa)
to type the Engelmann Spruce-Subalpine Fir (Kind 206)
forest cowl kind. It could additionally happen in pure or almost pure stands. Spruce
grows in 15 different forest sorts acknowledged by the Society of American
Foresters, often as a minor part or in frost pockets (95):

201 White Spruce

205 Mountain Hemlock

208 Whitebark Pine

209 Bristlecone Pine

210 Inside Douglas-Fir

212 Western Larch

213 Grand Fir

215 Western White Pine

216 Blue Spruce

217 Aspen

218 Lodgepole Pine

219 Limber Pine

224 Western Hemlock

226 Coastal True Fir-Hemlock

227 Western Redcedar-Western Hemlock

The composition of the forest through which Engelmann spruce grows is
influenced by elevation, publicity, and latitude (30). Within the Rocky
Mountains and Cascades, subalpine fir is its frequent affiliate in any respect
elevations. Within the northernmost a part of its vary alongside the Coast Vary
and within the Rocky Mountains of Canada, it mixes with white spruce (Picea
glauca),
black spruce (Picea mariana), Douglas-fir (Pseudotsuga
menziesii),
balsam poplar (Populus balsamifera), and paper
birch (Betula papyrifera). Within the Rocky Mountains of Montana and
Idaho, within the Cascades, and within the mountains of jap Washington and
Oregon, associates at decrease and center elevations are western white pine
(Pinus monticola), Douglas-fir, western larch (Larix
occidentalis),
grand fir (Abies grandis), and lodgepole pine
(Pinus contorta); associates at greater elevations are Pacific
silver fir (Abies amabilis), mountain hemlock (Tsuga
mertensiana),
alpine larch (Larix lyallii), and whitebark pine
(Pinus albicaulis). Within the Rocky Mountains south of Montana and
Idaho, and within the mountains of Utah, lodgepole pine, inside Douglas-fir
(Pseudotsuga menziesii var. glauca), blue spruce (Picea
pungens),
white-fir (Abies concolor), aspen (Populus
tremuloides),
and sometimes ponderosa pine (Pinus ponderosa)
and southwestern white pine (Pinus strobiformis), are frequent
associates at decrease and center elevations, and corkbark fir (Abies
lasiocarpa
var. arizonica), limber pine (Pinus flexilis),
and bristlecone pine (Pinus aristata) at excessive elevations.
Engelmann spruce extends to timberline within the Rocky Mountains south of
Idaho and Montana, and should type pure stands at timberline within the
southernmost a part of its vary. Within the Canadian Rockies of southwestern
Alberta and adjoining British Columbia and into the Rocky Mountains north
of Wyoming and Utah, and the Cascades, spruce often occupies moist websites
under timberline; its high-elevation associates type timberline forests
(6,20).

Rocky Mountain maple (Acer glabrum) (heat, moist websites);
twinflower (Linnaea borealis), (cool, moist websites); frequent
creeping juniper (Juniperus communis) (heat, dry websites); and
grouse whortleberry (Vaccinium scoparium), heartleaf arnica (Arnica
cordifolia),
boxleaf myrtle (Pachistima myrsinites), elk sedge
(Carex geyeri), mountain gooseberry (Ribes montigenum), and
fireweed (Epilobium angustifolium) (cool, dry websites) happen as
undergrowth all through a lot of the vary of Engelmann spruce. Undergrowth
vegetation is extra variable than tree associates, nonetheless. Undergrowth
characteristically discovered within the Pacific Northwest Area and the Rocky
Mountains and related ranges north of Utah and Wyoming embrace:
Labrador-tea (Ledum glandulosum), Cascades azalea (Rhododendron
albiflorum),
rusty skunkbrush (Menziesia ferruginea), woodrush
(Luzula hitchcockii), dwarf huckleberry (Vaccinium
cespitosum),
and blue huckleberry (Vaccinium globulare),
(cool, moist websites); false solomons-seal (Smilacina stellata), queenscup
beadlily (Clintonia uniflora), twistedstalk (Streptopus
amplexifolius),
and sweetscented bedstraw (Galium triflorum) (heat,
moist websites); pinegrass (Calamagrostis rubescens) and beargrass
(Xerophyllum tenax) (cool, dry websites); Oregongrape (Berberis
repens),
white spires, (Spiraea betulifolia), and massive
whortleberry (Vaccinium membranaceum) (heat, dry websites); and
marsh-marigold (Caltha leptosepala), devilsclub (Oplopanax
horridum),
and bluejoint reedgrass (Calamagrostis canadensis) (moist
websites) (14,39).

Undergrowth characteristically discovered within the Rocky Mountains and
related ranges south of Idaho and Montana embrace: mountain bluebells
(Mertensia ciliata) and heartleaf bittercress (Cardamine
cordifolia)
(cool, moist websites); thimbleberry (Rubus parviflorus)
(heat, moist websites); purple buffaloberry (Shepherdia canadensis),
Oregongrape, mountain snowberry (Symphoricarpos oreophilus), and
Arizona peavine (Lathyrus arizonicus) (heat, dry websites); and Rocky
Mountain whortleberry (Vaccinium myrtillus), groundsel (Senecio
sanguiosboides),
polemonium (Polemonium delicatum), daisy
fleabane (Erigeron eximius), prickly currant (Ribes lacustre),
sidebells pyrola (Pyrola secunda), and mosses (cool, dry
websites) (14).

Life Historical past

Replica and Early Development

Flowering and Fruiting- Engelmann spruce is monoecious; male and
feminine strobili are fashioned within the axils of needles of the earlier 12 months’s
shoots after dormancy is damaged, often in late April to early Could-
Ovulate strobili (new conelets) are often borne close to ends of the shoots
within the higher crown and staminate strobili on branchlets within the decrease crown
(38,102). Separation of female and male strobili inside the crown reduces
self-fertilization. The darkish purple male flowers are ovoid to cylindrical
and pendant. Feminine flowers are scarlet, erect, and cylindrical. Male
flowers ripen and pollen is wind disseminated in late Could and early June
at low elevations, and from mid-June to early July at excessive elevations. The
conelets develop quickly and shortly attain the scale of the previous cones that will
have endured from earlier years. The brand new cones mature in a single season and
are 2.5 to six.Three cm (1 to 2.5 in) lengthy. They ripen in August to early
September, open, and shed their seed. The cones might fall through the
following winter or might stay hooked up to the tree for a while (20,
89,102).

Seed Manufacturing and Dissemination- Though open-grown Engelmann
spruces start bearing cones when they’re 1.2 to 1.5 m (Four to five ft) tall
and 15 to 40 years previous, seed manufacturing doesn’t grow to be vital till
bushes are bigger and older. Probably the most plentiful crops in pure stands are
produced on wholesome, vigorous, dominant bushes 3.Eight dm (15 in) or extra in
diameter at breast top and 150 to 250 years previous. Engelmann spruce is a
reasonable to good seed producer (11,19,21). Good to bumper seed crops,
based mostly on the next standards, are typically borne each 2 to five years,
with some seed produced nearly yearly (19):

Variety of sound seeds/hectare Seed crop ranking
0-24,700 (0-10,000/acre) Failure
24,700-123,500 (10,000-50,000/acre) Poor
123,500-247,000 (50,000-100,000/acre) Honest
247,000-617,000 (100,000-250,000/acre) Good
617,000-1,235,000 (250,000-500,000/acre) Heavy
>1,235,000 (>500,000/acre) Bumper

There’s nice variation in seed manufacturing from 12 months to 12 months and from
space to space. In a single research on the Fraser Experimental Forest in Colorado,
annual seed manufacturing averaged solely 32,100 sound seeds per acre throughout
the interval 1956-65 (4). Just one good and two reasonable crops have been
recorded. In newer research, spruce seed manufacturing has been larger,
probably as a result of the research have been higher designed to pattern seed
manufacturing. One such research of seed manufacturing on 5 Nationwide Forests,
masking 42 area-seed crop years from 1962 to 1971, rated seed crops as 5
bumper, 1 heavy, 6 good, and the remaining 30 truthful to failure (74). Within the
one 12 months, 1967, {that a} bumper seed crop was produced on all areas, seed
manufacturing was the best ever recorded in Colorado (84). In one other
research on the Fraser Experimental Forest masking 15 years (1970-84) and 13
areas, seed manufacturing was rated 2 bumper, Three heavy, 2 good and eight truthful
to failure (21).

Within the northern Rocky Mountains, Boe (26) analyzed cone crops in Montana
between the years 1908 and 1953. Twenty-two crops noticed west of the
Continental Divide through the 45-year interval have been rated: 5 good, Eight truthful,
and 9 poor. East of the Divide, seed manufacturing was poorer: solely 2 good, 4
truthful, and 15 poor crops have been reported for a 21-year interval. In different
research within the Northern and Intermountain Areas, seed manufacturing was
rated pretty much as good to bumper in 1 12 months out of 5, with the opposite Four years rated
as failures (78,96).

Observations in spruce forests earlier than seedfall have indicated that half
of every seed crop is misplaced to cone and seed bugs (13). In a lately
accomplished research in Colorado, insect-caused lack of Engelmann spruce seed
averaged 28 % of the overall seed produced throughout a 4-year interval
(1974-1977) (88). The proportion of infested cones was highest throughout
years of poor seed manufacturing. The first seed-eating bugs have been a
spruce seedworm (Cydia youngana = (Laspeyresia youngana) and an
unidentified species of fly, probably a Hylemya, discovered solely within the
larval stage.

Some seed is misplaced from slicing and storing of cones by pine squirrels
(Tamiasciurus hudsonicus fremonti), however the precise quantity is
unknown. After seed is shed, small mammals corresponding to deer mice (Peromyscus
maniculatus),
red-backed mice (Clethrionomys gapperi), mountain
voles (Microtus montanus), and chipmunks (Eutamias minimus)
are the principal supply of seed loss. Undoubtedly, mammals devour
a lot seed, however the quantity isn’t identified and outcomes of research on
defending seed are conflicting. For instance, in western Montana, spruce
seedling success was little higher on protected than unprotected seed
spots (90), however in British Columbia, safety of spruce seed from
rodents was important to spruce regeneration success (94).

Cones start to open in September. Most seed is shed by the tip of
October, however some falls all through the winter. The small, winged seeds are
gentle, averaging about 297,000/kg (135,000/lb) (102). Practically all the
seed is disseminated by the wind; squirrels, different mammals, and birds are
not vital in seed dispersal.

Seed is dispersed lengthy distances solely in years of bumper seed crops. For
instance, research within the Rocky Mountains present that 237,200 to 617,800 sound
seeds/ha (96,000 to 250,000/acre) have been dispersed 122 to 183 in (400 to 600
ft) from the supply into clearcut blocks 183 m to 244 m (600 to 800 ft)
large (74). Seedfall in minimize stands ranged from 1,236,000 to 12,355,000
seeds/ha (500,000 to five,000,000/acre). In years of fine to heavy seed
crops, seedfall into cleared openings diminished quickly as distance from
seed supply elevated. Prevailing winds affect the sample of seedfall
in openings 61 to 244 m (200 to 800 ft) throughout, with about 40 % of
the seeds failing inside 31 m (100 ft) of the windward timber edge
(4,16,74). Seeffall then diminishes however at a much less speedy fee of decline as
distance will increase to about two-thirds of the way-46 to 183 m (150 to 600
ft)-across the openings. At that distance, the typical variety of seeds
falling is about 25 % (at 46 m [150 ft]) to lower than 5 % (at
183 m [600 ft]) of the variety of launched within the uncut stand (4,74,78,80).
Past this level, seedfall progressively will increase towards the leeward timber
edge, however is barely about 30 % of the seedfall alongside the windward edge
(13,16). Within the openings noticed, a U-shaped sample of seedfall was
poorly outlined. The “tailing-off’ means that vital
portions of seed have been launched during times of excessive winds (36).

Seedling Improvement- Viability of Engelmann spruce seed is
rated good and the vitality persistent. The common germinative capability
of spruce is greater than for a lot of related species (102):

Species Common germinative

capability
Engelmann spruce 69
Subalpine fir 31-34
Lodgepole pine 65-80
Western white pine 44
Inside Douglas-fir 60-93
Western larch 57
Grand fir 46-57
Western hemlock 53-56
Pacific silver fir 20-26
White fir 30-37

Viable seeds of spruce that survive over winter usually germinate
following snowmelt when seedbeds are moist and air temperature is no less than
7° C (45° F). Discipline germination of spruce over lengthy durations in
Colorado have ranged from Zero to 28 % of the sound seeds dispersed,
relying upon the seedbed and environmental components (9,73).

Within the undisturbed forest, spruce seeds germinate and seedlings grow to be
established on duff, litter, partially decomposed humus, decaying wooden,
and lumps of mineral soil upturned by windthrown bushes. Any disturbance
that removes the overstory produces new microhabitats (80). Beneath these
circumstances, germination and preliminary institution are typically higher
on ready mineral soil, and disturbed mineral soil and humus seedbeds
as a result of moisture circumstances are extra steady (27,35,41,73,94). Nevertheless,
preliminary survival of spruce on extreme websites at excessive elevations within the
Intermountain Area was greater on duff seedbeds than on mineral soil
seedbeds (37). Spruce seedling institution on burned seedbeds has been
variable. Success is said to severity of burn, depth of ash, and quantity
of uncovered mineral soil (29,80,91). Whatever the seedbed, excessive
preliminary mortality often slows institution of seedlings. As soon as
established (no less than 5 years previous), the flexibility to outlive isn’t
elevated by a mineral soil seedbed, however is favored by sufficient soil
moisture, cool temperature, and shade.

Engelmann spruce will germinate in all gentle intensities present in
nature, however 40 to 60 % of full shade is most favorable for seedling
institution at excessive elevations. Mild depth and photo voltaic radiation are
excessive at elevations and latitudes the place spruce grows within the central and
southern Rocky Mountains, and seedlings don’t set up readily within the
open. Planted seedlings usually develop a chlorotic look that has been
attributed to solarization-a phenomenon by which gentle depth inhibits
photosynthesis and which finally ends in dying (82). Mortality can
be decreased by shading seedlings. At low elevations and excessive latitudes in
the northern Rocky Mountains, spruce can grow to be established and survive in
the open (17). Spruce can set up and survive higher in low gentle
intensities than its frequent, illiberal associates corresponding to lodgepole pine,
Rocky Mountain Douglas-fir, and aspen, however at extraordinarily low gentle
intensities it can not compete favorably with such shade-enduring
associates because the true firs and hemlocks (20).

Engelmann spruce is restricted to chilly, humid habitats due to its
low tolerance to excessive temperature and drought (25,45). Nevertheless, photo voltaic
radiation at excessive elevations heats soil surfaces [up to 66° C (150°
F or more)] and will increase water losses from each seedlings and soil by
transpiration and evaporation (9,73,80).

Due to its gradual preliminary root penetration and excessive sensitivity to
warmth within the succulent stage, drought and warmth girdling kill many
first-year spruce seedlings. Drought losses can proceed to be vital
through the first 5 years of seedling growth, particularly throughout
extended summer time dry durations (9,34,73).

Tree seedlings within the succulent stage are significantly inclined to
stem-girdling. The cortex is killed by a temperature of 54° C (130°
F), however extended exposures to considerably decrease temperatures might also be
deadly. On the Fraser Experimental Forest, heat-girdling prompted a lot early
seedling mortality on unshaded seedbeds (9,73). Soil-surface temperature
exceeded 65° C (150° F) within the open on a north facet and 71°
C (160° F) on a south facet at 3200 m (10,500 ft) elevation in June.
Most air temperature throughout this era didn’t exceed 260 C (780 F).
In western Montana, at low elevations, soil floor temperatures exceeded
71° C (160° F) on light north slopes a number of instances throughout one
summer time (80). Early shade safety elevated survival of newly germinated
spruce seedlings; 30 to 50 % of the seedlings have been misplaced to
heat-girdling on unshaded plots, in comparison with 10 % on shaded plots.
In southwestern Alberta, when newly germinated spruce seedlings have been
disadvantaged of water, almost three-fourths of the mortality on 4 completely different
unshaded seedbed sorts was brought on by heat-girdling (34). Floor
temperatures as little as 45° C (113° F) prompted warmth girdling, however
losses weren’t excessive till soil floor temperatures have been above 50° C
(122° F). Shading decreased heat-girdling on all seedbed sorts. Soil
floor temperatures in extra of deadly ranges for spruce seedlings,
particularly on burned seedbeds, have been reported in British Columbia
(94).

Air and soil temperatures (under the floor) usually are not often immediately
answerable for seedling mortality, however they have an effect on development. In a development
chamber research of Engelmann spruce seedlings beneath 30 completely different
mixtures of day and night time temperatures, the best top and root
development, and prime and root dry matter manufacturing was with a diurnal
variation of 19° C (66° F) (air and soil) day temperatures and
23° C (73° F) (air and soil) night time temperatures (45). Shepperd
(92), utilizing the identical night time temperature regime, raised the day soil
temperature to 23° C (72° F) and considerably elevated root
development.

Frost can happen any month of the rising season the place spruce grows. It
is most certainly to happen in depressions and cleared openings due to
chilly air drainage and radiation cooling. Newly germinated spruce seedlings
are most inclined to early fall frosts. In a greenhouse and laboratory
research, new seedlings didn’t survive temperatures as little as -9.5° C
(15° F) till about 10 weeks previous (71). Terminal bud formation started
at Eight weeks; buds have been set and needles have been mature at 10 to 12 weeks after
germination.

After the primary 12 months, seedlings are most inclined to frost early in
the rising season when tissues are succulent. Shoots are killed or
injured by mechanical injury ensuing from tissue freezing and thawing.
Frost injury has been recorded in most years in Colorado (81). In gentle
frost years, injury was minor, however heavy frosts both broken or killed
all new shoots of open-grown seedlings.

In early fall, the mix of heat daytime temperatures, nighttime
temperatures under freezing, and saturated soil unprotected by snow are
conducive to frost-heaving. On the Fraser Experimental Forest, Colorado,
these circumstances typically occurred about 1 out of two years (9,73).
Frost-heaving has been one of many principal causes of first-year seedling
mortality on scarified seedbeds on north features (9). Moreover,
seedlings proceed to frost-heave after 4 rising seasons. Shading has
decreased losses by lowering radiation cooling.

The moisture situation of the seedbed through the rising season largely
determines first-year seedling survival. On some websites within the central
Rocky Mountains, summer time drought causes nice first-year mortality,
particularly in years when precipitation is low or irregular. On the Fraser
Experimental Forest within the central Rocky Mountains, drought and
desiccation prompted greater than half the first-year seedling mortality on
south features, and almost two-thirds of the overall after 5 years. On north
features throughout the identical interval, drought accounted for about 40 % of
first-year seedling mortality, and greater than half the mortality on the finish
of 5 years (9).

Within the northern Rocky Mountains, late spring and early summer time drought is
a critical risk most years to first-year seedlings. In western Montana,
all seedlings on one space have been killed by drought in a 2-week interval in
late summer time when their fee of root penetration couldn’t preserve tempo with
soil drying throughout a chronic dry interval (80). Late spring and early
summer time drought can be a critical reason for first-year seedling mortality in
the southern Rockies. Drought losses can proceed to be vital
all through the Rocky Mountains through the first 5 years of seedling
growth, particularly throughout extended summer time dry durations (9,73).

The moisture supplied by precipitation through the rising season is
significantly important to seedling survival through the first 12 months. A
greenhouse research of the results of quantity and distribution of moisture on
seedling survival (simulating frequent summer time precipitation patterns in
north-central Colorado) confirmed that beneath favorable seedbed and
environmental circumstances: (1) no less than 2.5 cm. (1 inch) of effectively
distributed precipitation is required month-to-month earlier than seedlings will survive
drought; (2) with this precipitation sample, greater than 3.75 cm (1.5 in)
of month-to-month rainfall isn’t prone to enhance seedling survival; however (3)
few seedlings will survive drought with lower than 5 cm (2 in) of rainfall
month-to-month when precipitation is available in just one or two storms (18).

Summer season precipitation might not at all times profit seedling survival and
institution. Summer season storms within the Rocky Mountains could also be so intense that
a lot of the moisture runs off, particularly from naked soil. Furthermore, soil
motion on unprotected seedbeds buries some seedlings and uncovers others
(80).

Understory vegetation will be both a profit or critical constraint to
spruce seedling institution (2,35,83). Spruce seedlings grow to be
established extra readily on websites protected by willows (Salix spp.),
shrubby cinquefoil (Potentilla fruiticosa), fireweed, and
dwarf whortleberry than within the open. As a result of these crops compete much less
aggressively for obtainable soil moisture than these listed under, the online
impact of their shade is useful to seedling survival. In distinction,
mortality happens when spruce seedlings begin close to clumps of grass or
sedges or scattered herbaceous crops corresponding to mountain bluebells, currants
(Ribes spp.), and Oregongrape that compete severely for
moisture and smother seedlings with cured vegetation when compacted by
snow cowl (83).

The one vital biotic issue affecting spruce regeneration on a
long-term research on the Fraser Experimental Forest was birds. About 15
% to 20 % of the overall mortality resulted from the clipping of
cotyledons on newly germinated seedlings by grey-headed juncos (Junco
caniceps) (9,73,75).

Damping-off, needlecast, snowmold, bugs, rodents, and trampling and
searching by giant animals additionally kill spruce seedlings, however losses aren’t any
larger than for some other species (20).

The variety of seeds required to provide a first-year seedling and an
established seedling (5 years previous) and the variety of first-year seedlings
that produce a longtime seedling fluctuate enormously, relying upon seed
manufacturing, distance from supply, seedbed, and different environmental
circumstances. In a single research in clearcut openings in Colorado through the
interval 1961-1975, masking all kinds of circumstances, on the typical
665 sound seeds (vary 602,066) have been required to provide one first-year
seedling, and 6,800 (vary 926-20,809) to provide a seedling Four or extra
years previous. A mean of 21 first-year seedlings was vital to provide
a single seedling Four or extra years previous, though as few as Four and as many as
24 first-year seedlings survived beneath completely different circumstances (74).

Facet and cultural remedies may also have an effect on institution of
Engelmann spruce. In one other Colorado research (masking the interval
1969-1982), a median of 18 sound seeds was required to provide a single
first-year seedling on shaded, mineral soil seedbeds on a north facet;
and 32 sound seeds have been wanted to provide a 5-year-old seedling. In
distinction, 156 seeds have been required to provide a first-year seedling on
shaded, mineral soil seedbeds on a south facet, and 341 seeds to provide
a 5-year-old seedling (8,9). Shearer (91), learning the results of
prescribed burning and wildfire after clearcutting on regeneration within the
western larch kind in Montana, additionally discovered that pure and planted spruce
survived higher on the north facet than on the south facet.

Environmental circumstances favorable and unfavorable to the institution
of Engelmann spruce pure regeneration are summarized in Determine 1.

Favorable Unfavorable
Seed crop Greater than 600,000 seeds pe hactare (242,800/acre Lower than 60,000 seeds per hectare (24,300/acre)
Facet North South
Temperatures Ambient air greater than 0° C (32° F) night time and fewer than 25°
C (77° F) day; most floor lower than 30° C (86° F)
Ambient air lower than 0° C (32° F) night time and greater than 25°
C (77° F) day; most floor larger than 30° C (86° F)
Precipitation Greater than 10 mm (0.Four in) per week Lower than 10 mm (0.Four in) per week
Soil
Mild-textured, sandy-loam Heavy-textured, Clay-loam
Seedbed 50 % uncovered mineral soil, 40 to 60 % useless shade, Duff
and litter lower than 5 cm (2 in), Mild vegetative cowl
10 % or much less uncovered mineral soil, 10 % or much less useless
shade, Duff and litter greater than 5 cm (2 in), Heavy vegetative cowl
Survival Seedlings greater than 12 weeks previous by mid-September, Low
inhabitants of birds and rodents that eat seeds and seedlings, Safety
from trampling, Snow cowl when frost-heaving circumstances exist
Seedlings lower than 12 weeks previous by mid-September,
Excessive inhabitants of birds and rodents that eat seeds and seedlings, No
safety from trampling, No snow cowl when frost-heaving circumstances
exist

Determine 1- Environmental circumstances favorable and unfavorable
to Engelmann

spruce regeneration
(9).

The early development of Engelmann spruce at. excessive elevations is gradual (60).
First-year spruce seedlings field-grown on mineral soil seedbeds beneath
partial shade in Colorado have a rooting depth of seven.6 to 10.2 cm (Three to 4
in), with a complete root size of 12.7 cm (5 in) (72). Within the Rocky
Mountains of Arizona and New Mexico, root depths of vigorous 1-year-old
seedlings averaged about 7.1 cm (2.Eight in) on each shaded mineral soil
seedbeds and on seedbeds the place humus depth was about 2.5 cm (1 in) (49).
Observations within the Rocky Mountains of Idaho and Montana and British
Columbia point out that first-year penetration of spruce seedlings averages
solely about 3.Eight cm (1.5 in) (80,94).

Preliminary shoot development of pure seedlings is equally gradual in Colorado.
First-year spruce seedlings are seldom taller than 2.5 cm (1 in). After 5
years, seedlings common 2.5 to 7.6 cm (1 to three in) in top beneath pure
circumstances, and 5.1 to 10.2 cm. (2 to Four in) in top on each partially
shaded and unshaded, ready, mineral-soil seedbeds. Seedlings 10 years
previous could also be solely 15.2 to 20.Three cm (6 to eight in) tall beneath pure circumstances,
and 25.7 to 30.5 cm (10 to 12 in) tall on each partially shaded and
unshaded, ready, mineral-soil seedbeds (7). After 10 years, bushes develop
sooner, averaging about 1.2 to 1.5 m (Four to five ft) in top in about 20
years in full solar or gentle overstory shade and in about 40 years beneath
reasonable overstory shade. Extreme suppression of seedlings does happen at
low gentle ranges. It isn’t unusual to search out bushes 80 to 120 years previous
only one.Zero to 1.5 m (Three to five ft) tall beneath the heavy shade of a closed
forest cover (76).

Seedling development has been considerably higher elsewhere within the Rocky
Mountains, particularly at low elevations and excessive latitudes. For instance,
in a single research within the intermountain West, annual shoot development of pure
10-year-old seedlings averaged 11.Four cm (4.5 in) on clearcut areas, and eight.3
cm (3.2 in) on areas with a partial overstory (67). Planted spruces, 5- to
8-years previous, averaged 51 to 61 cm (20 to 24 in) in top in Utah. In
Montana, planted spruces have been reported to succeed in breast top [1.4 m
(4.5 ft)] in about 10 years (21).

Early diameter development of Engelmann spruce is much less affected by
competitors for rising area than that of its extra illiberal associates.
In a research of seed spot density in northern Idaho, diameter development of
spruce seedlings after 17 years was solely barely larger on thinned seed
spots, and top development was unaffected by the thinning. In distinction,
diameter and top development of western white pine elevated considerably
because the variety of seedlings per seed spot decreased (79).

Vegetative Replica- Engelmann spruce can reproduce by
layering (47). It most frequently layers close to timberline, the place the species
assumes a dwarfed or prostrate type. Layering may also happen when solely a
few bushes survive fires or different catastrophes. As soon as these survivors have
elevated to the purpose the place their numbers alter the microenvironment
sufficient to enhance germination and institution, layering diminishes. In
common, this type of replica is insignificant within the institution
and upkeep of closed forest stands (21,76).

Sapling and Pole Stage to Maturity

Development and Yield- Engelmann spruce is among the largest of the
high-mountain species. Beneath favorable circumstances, common stand diameter
will fluctuate from 38.1 to 76.2 cm (15 to 30 in), and common dominant top
from 14 to 40 m (45 to 130 ft), relying upon website high quality and density
(20). Particular person bushes might exceed 101.6 cm (40 in) in diameter and 49 m
(160 ft) in top (60). Engelmann spruce is a long-lived tree, maturing
in about 300 years. Dominant spruces are sometimes 250 to 450 years previous, and
bushes 500 to 600 years previous usually are not unusual (13).

Engelmann spruce has the capability to develop effectively at superior ages. If
given adequate rising area, it’ll proceed to develop steadily in
diameter for 300 years, lengthy after the expansion of most related tree
species slows down (20,60).

Yields are often expressed for the overall stand. Engelmann spruce does
not usually develop in pure stands however in varied mixtures with related
species. Common quantity per hectare in old-growth (usually 250 to 350
years previous) spruce-fir could also be virtually nothing at timberline, 12,350 to
37,070 fbm/ha (5,000 to 15,000 fbm/acre) on poor websites, and 61,780 to
98,840 fbm/ha (25,000 to 40,000 fbm/acre) on higher websites. Volumes as excessive
as 197,680 to 247,100 fbm/ha (80,000 to 100,000 fbm/acre) have been
reported for very previous stands on distinctive websites (77,99). Common annual
development in virgin spruce-fir forests will fluctuate from a web loss on account of
mortality to as a lot as 494 fbm/ha (200 fbm/acre), relying upon age,
density, and vigor of the stand (69). Engelmann spruce often makes up at
least 70 % and infrequently greater than 90 % of the basal space in bushes
12.7 cm (5.Zero in) and bigger at breast top in these stands (76).

With immediate restocking after timber harvest and periodic thinning to
management stand density and keep development charges, development of particular person
spruce bushes and yields of spruce-fir stands will be enormously elevated and
the time required to provide the above volumes and sizes reduced- For
instance, in stands managed on the rising inventory ranges (GSL) thought of
optimum for timber manufacturing (GSL 140 to 180) on 140- to 160-year
rotations with a 20-year thinning interval, common volumes per hectare
will vary from 74,100 to 98,800 fbm/ha (30,000 to 40,000 fbm/acre) on
poor websites to 222,400 to 259,500 fbm 1 ha (90,000 to 105,000 fbm/acre) on
good websites. Quantity manufacturing declines -on all websites when rising inventory
stage is decreased under the optimum for timber manufacturing, and the decline
is bigger with every successive discount in GSL. Common annual development
will fluctuate from 445 to 1,606 fbm/ha (180 to 650 fbm/acre) (15). Furthermore,
since most subalpine fir will likely be eliminated in early thinnings, these yields
will likely be largely from Engelmann spruce.

Rooting Behavior- Engelmann spruce has a shallow root system. The
weak taproot of seedlings doesn’t persist past the juvenile stage, and
when bushes develop the place the water desk is close to the floor or on soils
underlain by impervious rock or clay hardpans, the weak, superficial
lateral root system frequent to the seedling stage might persist to previous age.
Beneath these circumstances, most roots are within the first 30 to 46 cm (12 to 18
in) of soil. However, the place spruce grows on deep, porous, effectively drained soils,
the lateral root system might penetrate to a depth of two.Four m (Eight ft) or extra
(20).

Response to Competitors- Engelmann spruce is rated tolerant in
its skill to endure shade (24). It’s undoubtedly extra shade-enduring
than inside Douglas-fir, western white pine, lodgepole pine, aspen,
western larch, or ponderosa pine however much less so than subalpine fir (probably the most
frequent affiliate all through a lot of its vary), grand fir, white fir, and
mountain hemlock. The Engelmann spruce-subalpine fir kind is both a
co-climax kind or long-lived seral forest vegetation all through a lot of
its vary. Within the Rocky Mountains of British Columbia and Alberta, and
south of Montana and Idaho, Engelmann spruce and subalpine fir happen as
both codominants or in almost pure stands of 1 or the opposite. Within the
Rocky Mountains of Montana and Idaho, and within the mountains of Utah,
jap Oregon and Washington, subalpine fir is the most important climax species.
Engelmann spruce might also happen as a significant climax species, however extra usually
it’s a persistent long-lived seral species. Pure stands of both species
will be discovered, nonetheless (6).

Though spruce-fir forests type climax or close to climax vegetation
associations, they differ from most climax forests in that many stands are
not really all-aged (60). Some stands are clearly single-storied,
indicating that fascinating spruce forests will be grown beneath even-aged
administration. Different stands are two- or three-storied, and multi-storied
stands usually are not unusual (13,68). These could also be the results of both previous
disturbances, corresponding to hearth, insect epidemics, or slicing, or the gradual
deterioration of old-growth stands on account of regular mortality from wind,
bugs, and illness. The latter is particularly evident within the formation of
some multi-storied stands. However, some multi-storied stands
seem to have originated as uneven-aged stands and are efficiently
perpetuating this age-class construction (16,43,104).

Though climax forests usually are not simply displaced by different vegetation,
hearth, logging, and bugs have performed an vital half within the succession
and composition of spruce-fir forests. Full elimination of the stand by
hearth or logging ends in such drastic environmental modifications that spruce
and fir are often changed by lodgepole pine, aspen, or shrub and grass
communities (80,97). The form of vegetation initially occupying the positioning
often determines the size of time it takes to return to a spruce-fir
forest. It could fluctuate from a couple of years, if the positioning is initially occupied by
lodgepole pine or aspen, to as many as 300 years, if grass is the
substitute group.

What is thought in regards to the utilization of water by Engelmann spruce in
Colorado will be summarized as follows: (1) leaf water potential decreases
in proportion to the transpiration fee however is influenced by soil
temperature and water provide; (2) needle water vapor conductance (immediately
proportional to stomatal opening) is managed primarily by seen
irradiance and absolute humidity distinction from needle to air
(evaporative demand), with secondary results from temperature and water
stress; (3) nighttime minimal temperatures under 3.9° C (39° F)
retard stomatal opening the following day, however stomata perform effectively from early
spring to late fall, and excessive transpiration charges happen even with snowpack
on the bottom; (4) leaf water vapor conductance is greater in Engelmann
spruce than in subalpine fir, however decrease than in lodgepole pine and aspen;
(5) Engelmann spruce bushes have much less complete needle space per unit space of
sapwood water conducting tissue than subalpine fir however greater than lodgepole
pine and aspen; and (6) Engelmann spruce bushes have a larger needle space
per unit of bole or stand basal space than subalpine fir, lodgepole pine,
and aspen. At equal basal space, annual cover transpiration of spruce is
about 80 % larger than lodgepole pine, 50 % larger than
subalpine fir, and 220 % larger than aspen. These excessive charges of
transpiration trigger Engelmann spruce to happen totally on moist websites
(50,51,52,53,54,55,56,57,58).

Each even- and uneven-aged silvicultural programs are acceptable to be used
in Engelmann spruce forests, however not all slicing strategies meet particular
administration aims (5,12,17). The even-aged slicing strategies embrace
clearcutting, which removes all bushes in strips, patches, blocks, or
stands with a single minimize; and shelterwood slicing, which removes bushes in
one, two, or three cuts and its modifications. Due to susceptibility
to windthrow, the seed-tree technique isn’t an appropriate option to regenerate
spruce. The seedbed is ready for regeneration after clearcutting, or
after the seed minimize with shelterwood slicing, by varied strategies ranging
from burning and mechanical scarification to solely that related to
logging exercise (5,12,17).

The uneven-aged slicing strategies acceptable to spruce are particular person
tree and group choice cuttings and their modifications, which take away
chosen bushes in all dimension lessons at periodic intervals over all the
space or in teams as much as 0.Eight hectares (2 acres) in dimension. Replica
happens repeatedly, however strategies of website preparation are restricted (12,13).

Shelterwood and particular person tree choice slicing strategies will favor
related species corresponding to true firs and hemlocks over spruce.
Clearcutting, group shelterwood, and group choice slicing strategies will
favor Engelmann spruce over these extra tolerant associates, however will
enhance the proportion of illiberal associates corresponding to lodgepole pine
and Douglas-fir (13).

Damaging Brokers- Engelmann spruce is inclined to windthrow,
particularly after any preliminary slicing in old-growth forests.

Partial slicing will increase the danger as a result of all the stand is opened up
and subsequently weak. Windfall is often much less round clearcuts
as a result of solely the boundaries between minimize and go away areas are weak,
however losses will be nice if no particular effort is made to find windfirm
cutting-unit boundaries (1,3). Whereas the tendency of spruce to windthrow
is often attributed to a shallow root system, the event of the
root system varies with soil and stand circumstances. Timber which have
developed collectively in dense stands over lengthy durations of time mutually
defend one another and shouldn’t have the roots, boles, or crowns to
face up to sudden publicity to wind if opened up too drastically. If the
roots and boles are faulty, the danger of windthrow is elevated.
Moreover, no matter sort or depth of slicing, or soil and stand
circumstances, windthrow is bigger on some exposures than others. Alexander
(13) has recognized spruce windfall threat in relation to exposures in
Colorado as follows:

Beneath Common:

  1. Valley bottoms, besides the place parallel to the path of prevailing
    winds, and flat areas.
  2. All decrease, and delicate, center north-east-facing slopes.
  3. All decrease, and delicate, center south- and west-facing slopes which might be
    shielded from the wind by greater floor not far to windward.

Above Common:

  1. Valley bottoms parallel to the path of prevailing winds.
  2. Light center south and west slopes not protected to the windward.
  3. Reasonable to steep center, and all higher north- and east-facing
    slopes.
  4. Reasonable to steep center south- and west-facing slopes protected by
    greater floor not far to windward.

Very Excessive:

  1. Ridgetops.
  2. Saddles in ridges.
  3. Reasonable to steep center south- and west-facing slopes not protected
    to the windward.
  4. All higher south- and west-facing slopes.

The danger of windfall in these conditions is elevated no less than one
class by such components as poor drainage, shallow soils, faulty roots
and boles, and overly dense stands. Conversely, the danger of windfall is
decreased if the stand is open-grown or composed of younger, vigorous, sound
bushes. All conditions grow to be very excessive threat if uncovered to particular
topographic conditions, corresponding to gaps or saddles in ridges at excessive
elevations to the windward that may funnel winds into the realm (1,3,13).

The spruce beetle (Dendroctonus rufipennis) is probably the most critical
insect pest of Engelmann spruce (86). It’s restricted largely to, mature
and overmature spruce, and epidemics have occurred all through recorded
historical past. Probably the most damaging out breaks was in Colorado from 1939 to
1951, when beetles killed almost 6 billion board ft of standing spruce
(64). Damaging assaults have been largely related to intensive
windthrow, the place downed bushes have supplied an ample meals provide for a
speedy buildup of beetle populations. Cull materials left after logging has
additionally prompted outbreaks, and there are examples of enormous spruce beetle
populations creating in scattered bushes windthrown after heavy partial
slicing. The beetle progeny then emerge to assault dwelling bushes, generally
significantly damaging the residual stand. Sometimes, critical spruce beetle
outbreaks have developed in overmature stands with no current historical past of
slicing or windfall, however losses in uncut stands that haven’t been
subjected to catastrophic wind storms have often been no larger than
regular mortality in previous development (13).

Spruce beetles want downed materials to standing bushes, but when downed
materials isn’t obtainable, then standing bushes could also be attacked. Giant,
overmature bushes are attacked first, but when an infestation persists,
beetles will assault and kill smaller bushes after the big bushes within the
stand are killed. Within the central Rocky Mountains susceptibility to beetle
assault can fluctuate by location; the next websites are organized from most to
least inclined: (1) bushes in creek bottoms, (2) good stands on benches
and excessive ridges, (3) poor stands on benches and excessive ridges, (4) blended
stands, and (5) immature stands (59,85). Evaluation of previous infestations
suggests the next sorts of stands are inclined to outbreaks: (1)
single- or two-storied stands, (2) excessive proportions of spruce within the
overstory, (3) basal space of 34 m²/ha (150 ft²/acre) or extra in
older and bigger bushes, and (4) a median 10-year periodic diameter
development of 1.Zero cm (0.Four in) or much less (87).

The western spruce budworm (Choristoneura occidentalis) is one other
probably harmful insect attacking Engelmann spruce and subalpine fir
(40). Though spruce and fir are among the many most popular hosts, budworm.
populations have been held in examine by mixtures of a number of pure
management factors- parasites, predators, ailments, and adversarial climatic
circumstances. The potential for future outbreaks is at all times current, nonetheless.
A wonderful abstract of the ecology, previous insecticidal -treatments, and
silvicultural practices related to western spruce budworm in northern
Rocky Mountain forests is given by Carlson et al. (28).

The commonest ailments of Engelmann spruce are brought on by wood-rotting
fungi that end in lack of quantity and predispose bushes to windthrow and
windbreak (46). In a current research of cull indicators and related decay
in Colorado, the most important root and butt fungi in mature to overmature
Engelmann spruce have been recognized as Phellinus nigrolimitatus, Flammula
alnicola, Polyporus tomentosus
var. curnatua, Gloeocystidiellum
radiosum,
and Coniophora puteana. Trunk rots, which prompted 88
% of the decay, have been related to Phellinus pini,
Haematosterceum sanguinolentum, Echinodontium sulcatum,
and Amylosterceum
chailletii.
Spruce broom rust (Chrysomyxa arctostaphyli) is additionally
frequent in spruce-fir forests. It causes bole deformation, lack of quantity,
and spiketops; will increase susceptibility to windbreak; and offers
an infection courts for decay fungi in spruce (20,46).

Dwarfmistletoe (Arceuthobium microcarpum) causes heavy mortality
in spruce in Arizona and New Mexico, nevertheless it has a restricted vary within the
Southwest and isn’t discovered elsewhere (44).

Engelmann spruce doesn’t prune effectively naturally. Skinny bark and the
persistence of useless decrease limbs make it inclined to destruction or
extreme damage by hearth (fig. 8). Many root and trunk rots in previous development
look like related to hearth damage. Due to the local weather the place
spruce grows, the danger of fireplace is lower than in hotter and drier climates
(20).

Particular Makes use of

Engelmann spruce-subalpine fir forests occupy the best water
yielding areas within the Rocky Mountains. In addition they present timber, habitats
for all kinds of recreation and nongame wildlife, forage for livestock, and
leisure alternatives and scenic magnificence (5). Nevertheless, these
properties are indigenous to the place spruce grows relatively than to any particular
properties related to the species.

The lumber of spruce is prone to include many small knots.
Consequently, it yields solely small quantities of choose grades of lumber, however
a excessive proportion of the frequent grades (70). Prior to now, spruce was used
principally for mine timbers, railroad ties, and poles. Right this moment, a lot of the
lumber is utilized in dwelling development the place nice energy isn’t required,
and for prefabricated wooden merchandise. Lately, rotary-cut spruce
veneer has been utilized in plywood manufacture. Different makes use of of spruce embrace
specialty objects corresponding to violins, pianos and plane elements (22,63).

The pulping properties of Engelmann spruce are wonderful. Lengthy fibers,
gentle shade, and absence of resins allow bushes to be pulped readily by
the sulfite, sulfate, or groundwood processes (22,101). The species has
been used for pulp within the northern Rocky Mountains however not within the central
or southern Rocky Mountains.

Genetics

Inhabitants Variations

Out there data on inhabitants variations of Engelmann spruce is
restricted to some research. For instance, spruce bushes from high-elevation
seed sources and northern latitudes break dormancy first within the spring,
and, when grown in low-elevation nurseries with low- and middle-elevation
seed sources,

are the primary to grow to be dormant within the fall. Conversely, low-elevation
and southern latitude seed sources incessantly are extra proof against spring
frosts, however are much less winter-hardy than middle- and high-elevation seed
sources (38). In a single research that in contrast seedlings from 20 seed sources,
starting from British Columbia to New Mexico, planted at an elevation of
9,600 ft in Colorado, seedlings from northern latitudes and decrease
elevations made one of the best top development (93). General survival from all
sources was 73 % with no vital variations amongst sources.

Races and Hybrids

There aren’t any acknowledged races or geographical forms of Engelmann
spruce. There’s plentiful proof that pure introgressive
hybridization between Engelmann and white spruce happens in sympatric
areas, particularly round Glacier Park in Montana (32). It has been
prompt that Engelmann and Sitka spruces cross in British Columbia, however
it appears extra doubtless that the crosses are between Sitka and white spruce.
Engelmann spruce has been artificially crossed with a number of different spruces,
however with solely restricted success (38).

Literature Cited

  1. Alexander, Robert R. 1964. Minimizing windfall round clearcuttings
    in spruce-fir forests. Forest Science 10:130-142.
  2. Alexander, Robert R. 1966. Stocking of replica on spruce-fir
    clearcuttings in Colorado. USDA Forest Service, Analysis Word RM-72.
    Rocky Mountain Forest and Vary Experiment Station, Fort Collins, CO. 8
    p.
  3. Alexander, Robert R. 1967. Windfall after clearcutting on Idiot
    Creek-Fraser Experimental Forest, CO. USDA Forest Service, Analysis Word
    RM-92. Rocky Mountain Forest and Vary Experiment Station, Fort Collins,
    CO. 11 p.
  4. Alexander, Robert R. 1969. Seedfall and institution of Engelmann
    spruce in clearcut openings: A case historical past. USDA Forest Service,
    Analysis Paper RM-53. Rocky Mountain Forest and Vary Experiment
    Station, Fort Collins, CO. Eight p.
  5. Alexander, Robert R. 1977. Chopping strategies in relation to useful resource
    use in central Rocky Mountain spruce-fir forests. Journal of Forestry
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  6. Alexander, Robert R. 1980. Engelmann spruce-subalpine fir 205. In
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    Eyre, ed. Society of American Foresters, Washington, DC. 148 p.
  7. Alexander, Robert R. 1969-1982. Information filed 1969-1982. USDA Forest
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  8. Alexander, Robert R. 1983. Seed: seedling ratios of Engelmann spruce
    after clearcutting within the central Rocky Mountains. USDA Forest Service,
    Analysis Word RM-426. Rocky Mountain Forest and Vary Experiment
    Station, Fort Collins, CO. 6 p.
  9. Alexander, Robert R. 1984. Pure regeneration of Engelmann spruce
    after clearcutting within the central Rocky Mountains in relation to
    environmental components. USDA Forest Service, Analysis Paper RM-254. Rocky
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  10. Alexander, Robert R. 1985. Diameter and basal space distributions in
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  11. Alexander, Robert R. 1986. Engelmann spruce seed manufacturing and
    dispersal, and seedling institution within the central Rocky Mountains.
    USDA Forest Service, Normal Technical Report RM-134. Rocky Mountain
    Forest and Vary Experiment Station, Fort Collins, CO. 9 p.
  12. Alexander, Robert R. 1986. Silvicultural programs and slicing strategies
    for old-growth spruce-fir forests within the central and southern Rocky
    Mountains. USDA Forest Service, Normal Technical Report RM-126. Rocky
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  13. Alexander, Robert R. 1987. Ecology, silviculture, and administration of
    the Engelmann spruce-subalpine fir kind within the central and southern
    Rocky Mountains. USDA Forest Service, Agriculture Handbook 659.
    Washington, DC. 144 p.
  14. Alexander, Robert R. 1988. Forest vegetation on Nationwide Forests in
    the Rocky Mountain and Intermountain areas: Habitat sorts and
    group sorts. USDA Forest Service, Normal Technical Report RM-162.
    Rocky Mountain Forest and Vary Experiment Station, Fort Collins, CO. 47
    p.
  15. Alexander, Robert R., and Carleton B. Edminster. 1980. Administration of
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    Experiment Station, Fort Collins, CO. 14 p.
  16. Alexander, Robert R., and Carleton B. Edminster. 1983. Engelmann
    spruce seed dispersal within the central Rocky Mountains. USDA Forest
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  18. Alexander, Robert R., and Daniel L. Noble. 1971. Results of watering
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