Index of Species Information

SPECIES:  Picea pungens

Introductory

SPECIES: Picea pungens
AUTHORSHIP AND CITATION : Pavek, Diane S. 1993. Picea pungens. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].
ABBREVIATION : PICPUN SYNONYMS : Picea parryana Sarg. Picea commutata Horton SCS PLANT CODE : PIPU COMMON NAMES : blue spruce Colorado blue spruce Colorado spruce silver spruce pino real TAXONOMY : The currently accepted scientific name of blue spruce is Picea pungens Engelm. [68,125]. It is a member of the pine family (Pinaceae). There are no recognized subspecies, varieties, or forms. Blue spruce does not readily hybridize with other conifers [105]. Throughout its range, it occurs with Engelmann spruce (Picea engelmannii Parry), but few if any natural hybrids are ever produced [22,105]. Artificial crosses have produced small amounts of seed with low (0.3 percent) germination [34,46]. Blue spruce, Engelmann spruce, and white spruce (Picea glauca) are sympatric in the Sweetgrass Hills of north-central Montana. Putative hybrids among all three spruce species have been reported [113]. Approximately 38 horticultural varieties of blue spruce have been developed [37,122]. LIFE FORM : Tree FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


DISTRIBUTION AND OCCURRENCE

SPECIES: Picea pungens
GENERAL DISTRIBUTION : Blue spruce is restricted to the central and southern Rocky Mountains. Its range extends from scattered populations in eastern Idaho and western Wyoming to better developed populations in Utah and Colorado. The range of blue spruce continues southward into Arizona and New Mexico [22,38,77,103,104]. It occurs rarely in north-central Montana [113]. ECOSYSTEMS : FRES20 Douglas-fir FRES21 Ponderosa pine FRES23 Fir - spruce FRES26 Lodgepole pine FRES28 Western hardwoods STATES : AZ CO HI ID MT NM UT WY BLM PHYSIOGRAPHIC REGIONS : 6 Upper Basin and Range 7 Lower Basin and Range 9 Middle Rocky Mountains 10 Wyoming Basin 11 Southern Rocky Mountains 12 Colorado Plateau 13 Rocky Mountain Piedmont KUCHLER PLANT ASSOCIATIONS : K012 Douglas-fir forest, K018 Pine - Douglas-fir forest K019 Arizona pine forest K020 Spruce - fir - Douglas-fir forest K021 Southwestern spruce - fir forest K022 Great Basin pine forest K025 Alder - ash forest SAF COVER TYPES : 206 Engelmann spruce - subalpine fir 210 Interior Douglas-fir 211 White fir 216 Blue spruce 217 Aspen 218 Lodgepole pine 219 Limber pine 235 Cottonwood - willow 237 Interior ponderosa pine SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : Blue spruce occurs as dominant or codominant in small stands or as scattered individuals. In riparian settings, blue spruce is codominant with cottonwoods such as narrowleaf cottonwood (Populus angustifolia) or balsam poplar (P. balsamifera) [7,85,117]. Blue spruce is more important in habitat type series of the central Rocky Mountains. Blue spruce series are restricted to cool, moist areas thoughout the southwestern mixed-conifer forests [1,26,120]. Common codominants are Engelmann spruce, white fir (Abies concolor), and Douglas-fir (Pseudotsuga menziesii) [3,26,88]. Blue spruce is often a long-lived seral species. It is seral in white fir, corkbark fir (Abies lasiocarpa var. arizonica), or fir phases of Engelmann spruce habitat types [3,39]. It infrequently occurs in the spruce-fir subalpine zone [31]. Some of the many publications that list blue spruce as an indicator or dominant in habitat or community types are: (1) Classification of the forest vegetation on the National Forests of Arizona and New Mexico [3] (2) Classification of riparian vegetation of the montane and subalpine zones in western Colorado [7] (3) Aspen community types of Utah [88] (4) A physical and biological characterization of riparian habitat and its importance to wildlife in Wyoming [91].

MANAGEMENT CONSIDERATIONS

SPECIES: Picea pungens
WOOD PRODUCTS VALUE : Blue spruce is not an important timber tree because it occurs infrequently, and the wood is brittle with many knots [38,65]. The wood is light, soft with numerous resin canals, close-grained, and weak [104,122]. When it is harvested, it is often cut and marketed with Engelmann spruce [77]. IMPORTANCE TO LIVESTOCK AND WILDLIFE : Blue spruce provides cover for a variety of bird and animal species [29]. Big game forage is good throughout blue spruce habitat types in northern New Mexico and southern Colorado [26]. Numerous birds eat blue spruce seeds [122]. Blue spruce cones are cached by red squirrels in Utah [128]. In a mixed-conifer forest in the White Mountains of Arizona, nongame birds moderately preferred blue spruce for cover and gleening for insects. In a comparison of usage in logged and control areas, mountain chickadee and ruby-crowned kinglet preferred blue spruce in unlogged areas only; yellow-rumped warbler preferred it in both treatment areas; and gray-headed junco preferred blue spruce in logged areas only [47]. PALATABILITY : Blue spruce is not a highly preferred food for either wildlife or domestic animals [10,103]. Deer browse blue spruce infrequently [122]. In mixed-conifer forests, blue spruce is the least desired browse species by elk and deer [67]. White-tailed deer in Conneticut browsed ornamental blue spruce an average of 0.5 percent throughout the summer [18]. Blue spruce can be used an an index of mule deer population size; young blue spruce are severely damaged by browsing during times of overpopulation [64]. NUTRITIONAL VALUE : The protein value of blue spruce is rated as poor, and its energy value is fair [29]. COVER VALUE : Blue spruce provides good environmental protection for elk, mule deer, white-tailed deer, small mammals, and small nongame and upland game birds in Colorado, Utah, and Wyoming. It gives poor cover for pronghorn in Colorado and Wyoming, and fair to poor cover for waterfowl in Utah and Wyoming [29]. Blue spruce was one of several species in a commercial conifer nursery used by white-tailed and mule deer for hiding and thermal cover during a severe winter in southeastern Wyoming [56]. Moose use blue spruce for shelter [75]. In Wyoming, moose used the blue spruce climax association an average of 5 percent over 4 years [63]. Where blue spruce occurred in a ponderosa pine forest in Colorado, cavity nesting birds showed no preference in tree species selection for nest sites [100]. Mixed-conifer forests of Arizona and New Mexico that blue spruce occur in are valuable summer habitat for game and nongame animals and birds [44,73]. Sensitive and endangered species use mixed-conifer stands in which blue spruce occurs. Such species include flammulated owls in Colorado, Jemez Mountain salamander of New Mexico, and northern goshawks in Arizona [20,94,98,99]. Bald eagle breeding areas at intermediate elevation in Wyoming are dominated by blue spruce and narrowleaf cottonwood. In the Snake River Unit, 28 percent of the nests were in blue spruce trees [114]. VALUE FOR REHABILITATION OF DISTURBED SITES : Blue spruce has been included in roadside reclamation on U.S. Highway 89 south of Afton, Wyoming. One year after grasses had been planted, container-grown blue spruce were planted [23]. Data on establishment success were not given. Blue spruce was chosen as one of several species to provide cover and foraging area for wildlife. This reclamation planting mediated habitat loss due to increased water levels in Rufus Woods Lake, Washington [17]. No data on establishment success were given. Blue spruce was planted in Canada as a part of shelterbelts to prevent wind erosion [54]. OTHER USES AND VALUES : Blue spruce is planted extensively as an ornamental in North America and Europe [13,77,104,]. Blue spruce are used as Christmas trees [38,65]. It is the state tree of Colorado and Utah [77,65]. OTHER MANAGEMENT CONSIDERATIONS : Silviculture: Blue spruce has an intermediate tolerance for single-tree selection harvesting [55]. Single-tree selection and diameter-limit harvest methods were compared on a Southwestern old-growth mixed-conifer stand in which blue spruce occurred. The single-tree selection method left the stand satisfactorily stocked with 54 percent damage to advance regeneration. Diameter-limit method left the stand understocked with 71 percent loss of advance regeneration [51]. Conifer regeneration by small patch clearcutting was also recommended for these forests [42,52]. Effective seeding distance to obtain adequate natural regeneration of blue spruce is about 3 to 4 times the height of the tree [80]. Because blue spruce is considered a late successional species, it is not suitable as a seed tree in clearcuts [53,106]. Silvicultural practices for mixed-conifer stands are reviewed in detail [67]. Blue spruce ranged from 2 to 28 inches (5.1-71.1 cm) d.b.h. with most trees at 2 inches (5.1 cm) in stand inventories of virgin mixed-conifer forest; no blue spruce died during the 5 years of monitoring. Initial blue spruce volume was 360 board feet per acre; final volume was 391 board feet per acre. Average annual growth of blue spruce was less than 0.2 inch (0.5 cm) [50]. In east-central Arizona, blue spruce were 3.05 square feet per acre (0.7 sq m/ha) basal area in a total 177.7 square feet per acre (40.8 sq m/ha) for the mixed-conifer forest. Blue spruce annual basal growth of 2.9 percent was the highest growth rate for all tree species present [33]. In blue spruce habitat series in central Colorado, total basal areas ranged from 169 to 300 square feet per acre (49-83 sq m/ha) with all size classes of blue spruce present [60,61]. Other Uses: In wet sites with well-developed soil, blue spruce timber potential is high; however, the timber value may be low. Blue spruce is often more valuable for wildlife habitat and food and for recreation [70]. Blue spruce is a component of mixed-conifer forests that have been a part of browse studies [41]. Equations exist for predicting forage production [12,40,76]. Forage production estimates include hiding and thermal cover for wildlife management. Since these mixed-conifer clearcuts require 50 to 100 years to regenerate, clearcut areas are a long-term forage resource for deer and elk [118]. Quaking aspen (Populus tremuloides) is often associated with blue spruce on upland sites. Treatment of conifers in these systems depends on whether aspen is to be maintained for livestock forage or wildlife habitat [25]. Blue spruce is a part of mixed-conifer stands that are managed for watershed [52]. Clearcuts in these forests increase water yield almost in proportion to the area cleared [24]. Artificial vegetative propagation of blue spruce is possible using short cuttings, grafting, and air layering [28,38,123]. Breeding commercial stock has been successful; however, interspecific crosses rarely yield viable hybrids [34,46,90,105]. Blue spruce pollen used in artificial crosses is viable for almost 3 years when stored at cold temperatures [36]. Methods for cone harvesting and seed extraction are discussed in detail [32,103]. Blue spruce have been planted in a wide range of environments. It has been a part of state nursery programs to stock oldfields in Ohio [93]. Blue spruce nursery stock is more drought resistant than other spruce species, and it can withstand temperatures to -40 degrees Fahrenheit (-40 deg C) [38]. It can tolerate some flooding. Forty percent of 3-year-old blue spruce seedlings survived 21 days under aerated, submerged conditions; all died after 28 days [82]. Blue spruce was included in a 30-year shelterbelt project in the northern Great Plains. Blue spruce was 13 feet (4 m) tall at 20 years with 32 percent of the original trees surviving [49]. It has been successfully used in shelterbelts in Montana, North Dakota, and South Dakota [9,119]. Planting recommendations have been discussed in detail [4,107]. Damaging Agents: Insects and disease reduce growth, viability, and vigor of blue spruce [37,124]. Heart and root rots, cone rusts, nematodes, snow molds, canker, and tip blight have an impact on blue spruce [38,89]. Silvicultural methods that minimize pathologic and insect problems are discussed in detail [2,45,106]. Calibrated ecosystem models that correlate microclimate with blue spruce stand information are useful for predicting the behavior of forest pathogens [83]. Tree ring patterns of blue spruce have been used to construct past occurrence of insect attacts [69]. Blue spruce is a host of western spruce budworm (Choristoneura occidentalis); outbreaks and symptoms are discussed in detail [16,78]. Blue spruce is an infrequent host of mountain pine beetle (Dendroctonus ponderosae) and spruce beetle (D. rufipennis), which kill other conifers [5,62]. Trees surviving infestation are more susceptible to other pathogens, insects, and windthrow [45,57]. Blue spruce is the principal host of western spruce dwarf mistletoe (Arceuthobium microcarpum) and minor host of other dwarf mistletoe species [58,59,124]. Infected blue spruce seedling mortality under a heavily infested canopy was twice that of the control [79].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Picea pungens
GENERAL BOTANICAL CHARACTERISTICS : Blue spruce is a native evergreen tree with a dense, pyramidal to spire-shaped crown [75,116,122]. It can be 70 to 115 feet (21-35 m) tall with a diameter up to 3 feet (0.91 m) [103,104,115,122]. The bark is 0.75 to 1.5 inches (1.9-3.8 cm) thick [104]. Branches are stout and horizontal to drooping [65,122]. The leaves are four-angled, stiff with sharp points, and 1 to 1.25 inches (2.5-3.2 cm) long [37,68]. Cones are 2.5 to 4 inches (6.4-10.2 cm) long with thin, flexible scales [77]. The seeds are 0.13 inch (0.3 cm) long, about half the length of the wings [104]. The largest blue spruce recorded was from Colorado at 126 feet (38.4 m) tall with 60.8 inches (154.4 cm) d.b.h. [38]. The oldest blue spruce was 600 years [86]. RAUNKIAER LIFE FORM : Phanerophyte REGENERATION PROCESSES : Blue spruce reproduces sexually. Natural vegetative reproduction does not occur, although epicormic shoots sometimes sprout on the trunks [38]. Seed production begins at about 20 years and peaks at 50 to 150 years [38,122]. Blue spruce is a good to prolific seed producer, producing full cone crops every 2 to 3 years [32,38,122]. Cones mature in August of the first year and have 85 to 195 seeds per cone [37]. Seeds are wind disseminated, falling within 300 feet (90 m) of the upwind timber edge [38]. Most germination occurs on exposed mineral soil; however, seeds germinate on a variety of substrates [37]. Natural germination rates usually are low; however, one study reported 80 percent germination [28,38]. Seeds germinate without stratification under a wide range of temperature and light conditions [38,103]. Blue spruce seedlings will establish beneath parent or other conifer canopies if understory vegetation is lacking or sparse [71]. Overall tree growth is slow [65]. In a nursery, blue spruce were 19.1 to 23.3 inches (48.5 to 59.2 cm) tall after 5 years [38]. Seedlings are susceptible to frost heaving and may be susceptible to drought due to shallow roots [2,66]. Blue spruce transplanted into the ponderosa pine (Pinus ponderosa) zone in the southern Rocky Mountains all died due to drought conditions [21]. Blue spruce was collected throughout its range and grown in a Michigan nursery. Growth rates slightly decreased as latitude of origin increased [13]. In a study in North Dakota, 73.6 percent of all blue spruce roots were in the top 2 feet (0.61 m) of the Fargo clay soil [127]. Despite its shallow roots, blue spruce is windfirm [122]. SITE CHARACTERISTICS : The shallow roots of blue spruce restrict it to moist sites where water is close to the surface [75]. Blue spruce occurs on montane streambanks; well-drained floodplains or cobble flats; first-level terraces; ravines; intermittent streams; or subirrigated, gentle slopes [37,60,75,104]. Throughout much of its range, blue spruce grows in cool climates that are subhumid to humid, characterized by low summer temperatures and low winter precipitation [37]. In the southern end of its range, it may be restricted to riparian areas in arid and semiarid climates; precipitation occurs bimodally with dry springs [92]. Average annual precipitation in blue spruce habitats varies from 18 to 24 inches (460-610 mm) [37]. Blue spruce typically occurs at mid-elevations. In Wyoming, blue spruce is abundant along streams at 6,750 feet (2,057 m) in elevation and extends up into subalpine zones to 10,499 feet (3,200 m) [37,61]. In Utah, blue spruce occurs from 6,500 to 8,400 feet (1,981-2,560 m) in elevation, where often the parent material is limestone or calcareous sandstone [15,38,65]. In Colorado, blue spruce occurs in canyons from 6,700 to 8,530 feet (2,042-2,600 m) in elevation and on canyon slopes from 9,800 through 11,500 feet (2,987-3,505 m) in elevation [61,70,74]. Blue spruce occurs from 7,500 to 9,842 feet (2,285-3,000 m) in elevation in Arizona and New Mexico [1,84,116]. Blue spruce grows on a variety of soil types. Usually, soils are young and undeveloped; however, soil textures may be deep sandy to gravelly loams that are well drained [37,61]. Soils are commonly derived from fluvium, alluvium, and colluvium [60,110]. Soils may have a litter layer up to 3.5 inches (9 cm) thick [61]. Soil temperature regimes are frigid in montane canyons to cryic at higher elevations [26,85]. Blue spruce stands are often associated with areas of cold air drainage [60,128]. Blue spruce occurs on flat to moderate (12 to 20 percent) slopes that often are north- to south- or southeast-facing [38,70]. Common associates not mentioned in Distribution and Occurrence are Rocky Mountain maple (Acer glabrum), thinleaf mountain alder (Alnus incana ssp. tenuifolia), wax currant (Ribes cereum), Utah honeysuckle (Lonicera utahensis), Gambel oak (Quercus gambelii), Saskatoon serviceberry (Amelanchier alnifolia), and common juniper (Juniperus communis) [3,37,70,88]. Other associated species are hairy goldenaster (Chrysopsis villosa), Fendler meadowrue (Thalictrum fendleria), Arizona fescue (Festuca arizonica), bluejoint reedgrass (Calamagrostis canadensis), and field horsetail (Equisetum arvense) [3,37,115,128]. SUCCESSIONAL STATUS : Facultative Seral Species Blue spruce occurs in various seral stages from pioneer to climax. Its successional status depends on location and associated species [38]. Blue spruce is a pioneer species in riparian communities that are subject to periodic disturbances, such as scouring and flooding [8,38,116]. It is present in all size classes along the riparian systems and on the lower slopes in the southwestern United States, where it may be a topoedaphic climax species [37]. Blue spruce is an intermediate to late, long-lived seral or climax species in montane or subalpine zones [6,38,106]. Blue spruce is intermediate in shade tolerance [38,111]. It may be seral to or climax with any of the conifer species in the mixed-conifer forests [30,37]. Quaking aspen and lodgepole pine (Pinus contorta) can be seral to blue spruce [87]. SEASONAL DEVELOPMENT : Reproductive buds of blue spruce form on shoots of the previous year [103]. Pollen is shed from April to June, depending on altitude. Cones mature during August or September of their first year; seeds disperse in fall and winter [37,103]. Some cones drop the first winter; however, most are retained 2 to 3 years [37]. Seeds germinate in the spring or summer after dispersal [38].

FIRE ECOLOGY

SPECIES: Picea pungens
FIRE ECOLOGY OR ADAPTATIONS : Blue spruce is easily killed by fire [67,126]. It has thin bark and shallow roots which make it susceptible to hot surface fires [14]. Blue spruce is slow to self-prune lower branches; therefore, surface fires can crown [19]. Blue spruce foliage has moderately volatile oils [109]. Crowns are dense and highly flammable [106,109]. However, surviving blue spruce remain windfirm in stands opened by fire [14]. In riparian areas where blue spruce occurs, intervals between fires are about 350 to 400 years. Severe fires occur infrequently, and succession back to the original community is often relatively rapid (15 to 35 years). Depending on the site, blue spruce may be the dominant seral tree [19]. Successive fires may prevent blue spruce from dominance because it is fire intolerant. Historical fire frequency in mixed-conifer forests was about 22 years, based on fire-scarred trees in the White Mountains of Arizona [27]. Fire suppression during the past 100 years has made the mixed-conifer forest in which blue spruce occurs more susceptible to fire; however, blue spruce may be dominant in some areas because of the longer fire-free intervals. POSTFIRE REGENERATION STRATEGY : Tree without adventitious-bud root crown Secondary colonizer - off-site seed

FIRE EFFECTS

SPECIES: Picea pungens
IMMEDIATE FIRE EFFECT ON PLANT : Fire kills blue spruce. Low severity fires will kill saplings and seedlings [2]. Slow burning of fine fuels will kill the shallow roots of blue spruce [14]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Blue spruce does not sprout after fire [109]. Rates of establishment will vary depending on proximity of seed trees and moisture. Seed must be transported from off-site. Blue spruce will establish by wind-dispersed seed that readily germinates on the mineral soil exposed by fire. Small mammals and birds may also carry cones or seeds into a burn. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : Fire is less frequent in montane mixed-conifer forests at lower elevations where Douglas-fir is dominant with blue spruce than in ponderosa pine types. Quaking aspen is seral and present because of fire in these forests. Prescribed fire here would increase habitat and browse for wildlife [108]. Blue spruce is not recommended for fire shelterbelts based on studies in Victoria, Australia. Fuel ladders form from persistent dead low branches [109]. Fuel prediction is difficult because of the large variation in natural fuel loadings in the forests where blue spruce occurs [101]. Therefore, Sackett [102] determined average squared diameters and specific gravities of blue spruce and seven other conifer species in Arizona and New Mexico. This established weight and volume of fuels using planar intersect method. Greatest accumulations on the mixed-conifer forest floor come from fermentation and humus layers [43]. One fuel loading estimate was an average of 44 tons per acre (98 t/ha) [128].

References for species: Picea pungens


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