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Wildlife, Animals, and Plants |
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VALUE AND USE
WOOD PRODUCTS VALUE:Historically white fir was considered undesirable for timber. Now that the availability of premium timber species has declined, white fir is being recognized as a highly productive and valuable tree species and is widely used in the wood products industry [109,148,178]. White fir is a general, all-purpose, construction-grade wood used extensively for solid construction framing and plywood, and to a lesser extent, for pulpwood [148,277]. It is also used for poles and pilings because of its straight grain and low taper, but requires large amounts of preservatives because the heartwood decays rapidly. It is poorly suited for firewood because of its low specific gravity and heat production (80% as much heat by volume as Douglas-fir produces), but it is used for firewood anyway [277].
IMPORTANCE TO LIVESTOCK AND WILDLIFE:Stands dominated by white fir seldom produce enough forage for domestic livestock grazing except on harvested or open forest sites, or where grasses and sedges dominate the understory [81]. These forests do, however, provide abundant browse and cover for large and small wildlife species [83,294]. Deer, elk, and bear often use white fir habitats as either summer or winter range [2,189]. Mule and black-tailed deer generally eat small amounts of white fir during the spring, fall, and winter, and sometimes larger amounts during the summer [152,177,189]. Mule deer are especially fond of succulent, new white fir growth in the spring [114,178,185]. Spring browsing of white fir by deer can be particularly heavy when small white firs are the only green food available; all of the current or previous year's growth may be consumed [119]. Porcupines enjoy the bark of white fir, and may destroy saplings in their enthusiasm [138,185,201]. Rodents feed on the cambial tissue of white fir in preference to that of Douglas-fir. During the winter, mice feed on the leaders of small white firs near snow level. In the spring, they feed on seedlings, sometimes destroying a large proportion of the current year's seedlings [138,201]. Pocket gophers also feed on white fir seedlings in the winter and spring [157,178]. White fir needles are an important part of the diet of blue grouse [127,197]. White fir seeds are eaten by several species of small mammals and birds including grouse [183,322], chipmunks and mice [323], flying squirrels [345], chickadees, crossbills, and Clark's nutcracker [127,197]. In the southern Cascades and Sierra Nevada, the Douglas squirrel cuts and caches white fir cones during late summer and fall, before the cones are fully mature [106,114,185]. Hollow logs and snags of white fir can be important to various birds and animals for foraging in the interior wood [240]. There are about 33 species of mammals commonly present in the white fir forest type in California, and of these 7 are generally associated with mature forests [178]. Hollowed-out trunks of old white fir trees, dead or alive, are denning sites for mammals ranging form weasels to porcupines to black bears [186]. In one study, abundance of white fir had a strong positive association with California mountain beaver habitat use [42]. About 123 species of birds are found in the white fir type of California and southern Oregon, about 50 of which are associated primarily with mature forests, and many of which use mature white fir trees and snags for foraging, roosting, nesting and/or breeding [155,178,212,228,317]. These include bald eagles [78,292], northern spotted owls [107,182,303], California spotted owls [44,61,128,318,319], flammulated owls [320], brown creepers and red-breasted nuthatches [1]. In Oregon, mature white fir forests provide nesting and feeding habitat for important bird species, such as the goshawk, pileated woodpecker, white-headed woodpecker, and, when near lakes or streams, osprey and bald eagle [149]. Reptiles in white fir forests are represented by 17 species, mostly at lower elevations, 8 of which are associated with mature forests [178]. In the southwest, desert bighorn sheep and white-tailed deer occasionally browse white fir [183,276]. In the Rocky Mountains, red squirrels cache white fir cones during late summer and fall before the cones are fully mature [106,114,185]. Some white fir habitat types in the Southwest and Utah provide habitat for black bears and cougars and have high cover value for wildlife [190,294]. In riparian woodlands in the Southwest, white fir is often a codominant species with hardwoods such as maples. These woodlands tend to be small in area, but provide unique and critical habitat for many species of wildlife such as the Arizona gray squirrel, river otter, zone-tailed hawk, common black hawk, American dipper, summer tanager, bullock oriole, yellow warbler, Arizona alligator lizard, Sonoran mud turtle, and canyon tree frog [12,101,294]. At the southern end of its range in the Madrean region, white fir occurs in "island" habitats at the uppermost elevations of isolated mountain ranges, providing small areas of geographically unique habitat for wildlife. An example are the wildlife species present in the Rincon Mountains of Saguaro National Monument, Arizona, presented by Davis and Sidner [73]. The highly variable stand structure with multi-storied shrub layers in some southwestern white fir habitat types provides increased microhabitat diversity for birds [101,294]. White fir forests in the Southwest provide habitat for Mexican spotted owls in Arizona, New Mexico [116,194], and Utah [341]; goshawks in Arizona [70,196,255]. Thick-billed parrots, reintroduced in the mountains of southeastern Arizona, occur in mixed-conifer forests with white fir [279]. Several species of amphibians and reptiles may be found in white fir montane mixed conifer forests such as that at upper elevations in Saguaro National Monument [193]. Two species of endangered salamanders (Jemez Mountains salamander and Sacramento Mountain salamander) in New Mexico are found in mixed conifer forests dominated by white fir [250].
PALATABILITY:Because they contain resins, terpenes, and other substances that make the foliage irritating to the digestive tract, most conifers are not particularly palatable to grazing animals. White fir may be slightly palatable to goats [266]. Immature foliage is enjoyed by mule and black-tailed deer [119,189]. White fir seeds are palatable to numerous species of small rodents, although seeds of Douglas-fir, ponderosa pine, and sugar pine are preferred [106,249].
NUTRITIONAL VALUE:White fir browse is low in protein [92].
COVER VALUE:White fir's evergreen foliage provides good hiding cover year-round and is usually continuous from the ground upward on trees less than 8 to 10 inches (20-25 cm) dbh [148]. White fir stands of this nature provide excellent hiding cover for large wildlife species such as deer, elk, and black bear [141,187]. If enough shrubs are present in the understory to provide adequate hiding cover, mature white fir forests are used by deer during fawning and by elk during calving [149,174]. In mixed conifer forests of the Sierra Nevada, cavity-nesting birds prefer white fir snags over the snags of associated trees. Cavity nesters using white fir snags include the American kestrel, mountain chickadee, brown creeper, mountain bluebird, house wren, tree swallow, northern flicker, and several nuthatch, sapsucker and woodpecker species [251]. Other forest songbirds nest within white fir foliage. Hollowed trunks of older trees are used by several species of mammals such as black bears, for hibernation; American martens, for dens and rest sites; and bushy-tailed woodrats, flying squirrels and other small mammals for cover [185,240]. Most bear dens in Yosemite National Park are found in the hollowed trunks of white fir [202].
VALUE FOR REHABILITATION OF DISTURBED SITES:White fir can be planted on disturbed sites within forest vegetation types where it naturally occurs. It is a good soil stabilizer and may be particularly useful on roadcuts [248]. Fir seedlings exhibit very slow initial growth, and are therefore usually outplanted as 2- to 3-year-old seedlings or 3- to 4-year-old transplants [108]. Transplanting nursery stock is more successful than direct seeding [248]. White fir can be propagated from stem cuttings, which root easily when treated with a rooting medium [88]. Because this wide-ranging tree exhibits a large degree of genetic variation, seed or planting stock for rehabilitation projects is best provided by a local source [214,248]. Methods for collecting, processing, testing, storing, and planting white fir seeds have been discussed in detail [90,108].
OTHER USES AND VALUES:White fir is a valuable ornamental tree. It is often used for ornamental plantings in rural and urban landscapes in northern U.S. cities, because it is attractive and frost-hardy [185,202]. White fir is not, however, very tolerant of air pollution and therefore seems best suited for suburbs or rural areas [175]. White fir eventually attains great size and is best grown in parks or other open public areas. White fir is used extensively in the Christmas tree industry [148,178]. Native Americans used the needles for tea [149].
MANAGEMENT CONSIDERATIONS:Ecosystem management: Changes in white fir ecosystems are evident and well documented and are attributed to many human activities and their interactions on the landscape (for example, see [72,209,234]). Some management objectives call for some form of "ecological restoration", or the "restoration of natural conditions", or the reversal of recent, human-caused ecological degradation, based on reference conditions. These reference conditions can occur over a range of temporal and spatial scales, and are determined by detailed study of historical and ecological data, including fire history, of a particular site or ecosystem [115,123,161,227,289]. Once these historical reference conditions are estimated, they may be used to delineate management objectives based on conditions that are within a range of historical variability for a particular site, and the tools necessary to achieve them [123]. For example, decades of research in giant sequoia groves of the Sierra Nevada [e.g. 46,47,167,261,285,291,293,295] make it one of the better understood ecosystems, and reference conditions are available for these forests [285,289]. Still, there are limitations here that may also be faced by scientists and land managers in other forest ecosystems [289]. Researchers have found it easier to determine past fire regimes than to determine past grove structures. Surface fires had 2 to 3-year mean fire return intervals at Sequoia National Park for more than 1300 years before the era of fire suppression [172,295]. Most giant sequoia groves are now overwhelmingly dominated by white fir which could not have survived in such numbers under such a fire regime [288]. This increased density of white fir in giant sequoia groves may have implications for changes in the natural fire regime from surface fires to crown fires. It may also have implications for damage by insects and diseases, such as annosus root rot, that may also affect giant sequoia [247]. Using silvicultural techniques to restore prehistoric structure alone may not restore healthy ecosystem function, but it is possible that restoration of fire may restore the former structure of sequoia groves [288,289]. For example, giant sequoia seedlings numbered between 7,514 and 40,130 per acre (18,560 and 99,120 per ha) after prescribed burning at Redwood Mountain [170]. Conversely, where group selection harvest with different slash treatments was applied in giant sequoia stands in an attempt to simulate the structural complexity of the prehistoric, patchy, high intensity fire regime that once existed there, regeneration in the small openings was dominated by white fir instead of giant sequoia. Giant sequoia seedling density ranged from 0 to 57seedlings/acre (0-141.5 seedlings/ha). Important ecosystem processes, such as increased seed dispersal in giant sequoia following patchy, high intensity fire and large scale nutrient cycling, are not duplicated by harvest alone [284]. It may be necessary to use a combination of treatments. In areas shifting from fire-climax ponderosa pine to fire-intolerant white fir, the ecologically appropriate treatment may be to thin white fir stems from below and follow with prescribed fire, monitoring the effects of the treatment and fine-tuning as needed. It is important that such activities avoid the following: 1) excessive opening of overstory canopies; 2) road building and damage to soils; 3) thinning in mid- to high elevation and moist forests where dense understories and long fire intervals are more characteristic; and 4) large-scale conversion of closed-canopy forests to open-canopy, even-aged stands since this would adversely affect many wildlife species such as the northern spotted owl and lynx who depend on closed canopy and dense forests, respectively [79]. Leaving some mid and late successional stands would allow for a diversity of stand ages, structures, characteristics on the landscape. Definitions and characteristics of different stages of forests in which white fir is a component are available [280,281]. Wildlife: Managing white fir forests for wildlife habitat involves complex interactions of several plant and wildlife species, and consideration of stages of forest development that are important to the species of interest. Relationships of habitat for Rocky Mountain elk and Rocky Mountain mule deer to timber management and stand characteristics in white fir forests in Oregon have been explored [49,76]. White fir habitat is not used heavily by Columbian black-tailed deer who seem to prefer the mixed conifer, montane hardwood and annual grassland habitats on the west slope of California's coast range, suggesting that the exclusion of fire and subsequent changes in these forests may have adversely affected habitat for these deer [192]. Bird species diversity was found to be higher in the early postfire and mature forest successional stages in the Sierra Nevada, and lowest in the brush-dominated phase of succession [51]. Hollow logs and snags can be important to various birds and animals for nesting, foraging, denning and roosting sites [240]. Therefore, leaving snags and logs might be an important consideration in a management prescription. Leaving "high-cut stumps" was evaluated as a possible method for simulating snags for wildlife habitat [228]. White fir forests are home to several sensitive, threatened and endangered species. Two species of endangered salamanders (Jemez Mountains salamander and Sacramento Mountain salamander) in New Mexico are found in mixed conifer forests dominated by white fir and are vulnerable to some forest management practices [250]. Management recommendations for wildlife habitat are given for wildlife in general [60], nongame birds [275], the northern goshawk and its prey species in the southwest [70,255], for the California spotted owl [50,210,318,319], Mexican spotted owl [95,311], and bald eagle [78,80]. Forest practices that emphasize the retention of mature trees and coarse woody debris also promote the abundance and diversity of truffles, which are integral an functionally important members of forest ecosystems [23]. Timber harvest and regeneration treatments: White fir can be regenerated naturally or artificially. Advanced regeneration of white fir greater than 4.5 ft (1.4 m) at the time of release tended to grow taller than projected growth of planted seedlings of Douglas-fir on similar sites in southwest Oregon [173]. Most white fir stands have been managed for timber production using even-aged management techniques [178,180,181]. Even-aged management by seed tree method is described by Aune [32] with guidelines for selecting appropriate individuals to leave as seed trees in white fir. Clearcutting and shelterwood cutting have been successful at promoting regeneration of white fir, as long as the maximum downwind width of openings does not exceed 1.5 to 2 times the height of trees left as seed sources [178]. Shelterwood methods generally result in the best regeneration of white fir [201,260], although heavy overstory removal in some areas may favor Douglas fir, ponderosa pine, or hardwoods over white fir. With less overstory removal, such as by light shelterwood cutting or selection cutting, regeneration of shade-tolerant white fir will be favored. Any kind of partial cutting where white fir is present will favor white fir and increase its importance in the stand [178]. Partial harvesting of an old-growth interior ponderosa pine stand in northeastern California resulted in increased growth rate of white fir. However, mortality exceeded recruitment into the largest size classes presumably due to competition with the tremendous number of smaller stems stressing the older trees. The dramatic increase in the smaller diameter classes is most likely a response to partial cutting without burning [87]. Group selection and patch clearcutting resulted in good regeneration in an Arizona mixed conifer forest [94]. The group selection method is discussed by Laacke [179] with reference to white fir. Response of white fir to different timber harvest treatments are given by Vora [326], and show an increase in white fir numbers with no treatment as well as with heavy overstory removal in northeastern California after 40 years. These unexpected results impress the variability of ecosystem response and suggest site specific management plans. Uneven-aged management, such as the single-tree selection method [132], may produce stands that most closely resemble reference conditions. However, uneven-aged management of white fir, requiring repeated selective harvests (multiple entry), has not been recommended in the past because it promotes several pest problems, such as decay fungi and insects, which take advantage of wounded trees and freshly cut stumps, especially in the Pacific Northwest [9,118,148,238]. Thinning operations also favor these pests because 20 to 50% of the residual trees may be wounded [9,148]. Suggestions for reducing injuries during stand management activities are given by Aho and others [10]. Immediate removal of stumps may be effective in preventing the spread of disease fungi, but it is highly disturbing to the soil and may cause excessive erosion and loss of site productivity [97]. Chemically treating freshly cut fir stumps may be an alternative [288]. Competition and Animal damage: Establishment of white fir may be difficult where graminoid cover is dense [294]. Dense brush does not prevent regeneration of white fir, but it may slow down establishment, with white fir taking 30 to 50 years to overtop shrubs [180]. Managers have sometimes used cattle to control brush and aid in regeneration following clearcutting in the mixed conifer forests of the Sierra Nevada [21]. However, free-ranging cattle favor riparian areas in these forests, so their usefulness in this endeavor may be related to the proximity of the site to a riparian area [166]. Furthermore, white fir seedling establishment may be difficult where damage from livestock trampling is possible [157,178]. Protective plastic tubing can be used to protect seedlings threatened by gophers and other rodents. Browsing of seedlings by deer and elk can reduce height growth for years, but seldom kills plants. Browsing does not seriously affect growth of trees over 4 feet (1.2 m) tall [180]. Methods of mechanical and chemical control of shrub competition are available [67,180]. Pests and diseases: Heavy to severe mortality of white fir was reported throughout Idaho and Utah in the late 1980's most likely attributed to insects and diseases [199]. Filip and Schmitt [98] provide a review of root diseases, stem decays, and dwarf mistletoes of true firs, and the effects of management techniques, especially silvicultural techniques such as commercial and precommercial thinning on these diseases. It has been argued that if we leave late-successional reserves or "overmature" stands for critical habitat in the short-term that we are increasing "the risks of insect outbreaks, tree-killing pathogens, and catastrophic wildfires" [62,86]. Others suggest that insect and disease outbreaks are part of the evolutionary scene and helped to create mosaics of contrasting successional stages on the landscape [223]. Dwarf mistletoes: The trunks of California white fir are often malformed or broken off where dwarf-mistletoe infections have created stem cankers that cause weak spots and reduce the strength of the lumber produced [178,185,200]. Two species, white fir mistletoe (Phoradendron bolleanum ssp. pauciflorum), and white fir dwarf mistletoe (Arceuthobium abietinum f. sp. concoloris) are responsible, and can be a serious problem in some areas [137,178]. White fir dwarf mistletoe occurs on white fir throughout most of its range in California, Nevada, Arizona, and southern Oregon [137]. White fir may be infected by Douglas-fir dwarf mistletoe in Utah and New Mexico [56,137]. Infected trees may suffer significant growth losses and become more prone to infection by other diseases such as Cytospora abietis, a fungus that causes "flagging" and kills branches and further reduces growth [137]. Infected trees are also more susceptible to attacks by bark beetles and heart rots. Dwarf mistletoe and fir canker were the most important pathogens, followed by fir engraver, associated with death in white fir in Sequoia National Park over a 5 year period [233]. A detailed discussion of the dwarf mistletoes as ecological components of forest canopies is provided by Mathiasen [200]. Decay fungi: White fir can be severely damaged or is highly susceptible to a number of decay fungi including annosus root disease (Heterobasidion annuosum), Armillaria root disease (Armillaria spp.), laminated root diseases, yellow cap fungus (Pholiota limonella), Indian paint fungus (Echindontuim tinctorium), and white pocket rot (Phellinus pini) [97,239,272]. Decay fungi may enter the tree through wounds (e.g. annosus) associated with mechanical injuries, fire, insects and/or frost cracks; or may be dormant in the tree and activated by wounding (e.g. Indian paint fungus) [8,11,96,238]. Stem decay losses in white fir can be large, with over 20% attributable to annosus root disease in eastern Oregon [10,11]. Annosus root disease may be the most damaging pathogen to true firs east of the Cascades in the Pacific Northwest [118]. Although it does not usually kill white fir directly, annosus produces moisture stress and loss of vigor and can predispose the tree to attack by bark beetles. Filip [96] presents an equation for estimating the volume of timber loss due to stem decay in white and other true fir stands. Symptoms and diagnosis of annosus root disease are given by Schmitt [270]. Insects: The fir engraver beetle is the most damaging white fir pest, causing major losses throughout the range of white fir [343]. Maintenance of stand health and vigor is the only known control. Of the many insects that feed on white fir foliage, a few can cause serious damage. The Douglas-fir tussock moth is a serious defoliator [178,340,342], as are the western spruce budworm [195,223], the New Mexico fir looper, and the white fir needle miner [178]. White fir seedlings and saplings lack chemical defenses against, and tend to be killed by budworm feeding, while healthy mature trees usually survive [223]. Susceptibility to budworm may be reduced by thinning young white fir [223,294]. Extensive spraying with chemical insecticides has been shown to be futile [223]. Further discussion of western spruce budworm population dynamics and ecology is available [325,343]. Insects that may cause damage to white fir cones and seeds include seven genera, the most abundant and damaging of which are seed maggots and the fir cone looper [178]. Cutworms may cause significant seedling mortality [119,178]. White fir is sensitive to oxidant damage from air pollution [157,216,262], but less sensitive than some associated species [40].
Related categories for SPECIES: Abies concolor | White Fir |
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