Fire Effects Information System (FEIS)
FEIS Home Page

Table of Contents

Figure 1—Bristlecone fir on Cone Peak, Monterey County, California. Image by Mark W. Skinner, hosted by the USDA-NRCS PLANTS Database. Used with permission.

SUMMARY


This review summarizes the fire effects information and relevant ecology of bristlecone fir that was available in the scientific literature as of 2020.

Bristlecone fir is a rare fir that is taxonomically separated from other fir species due to its unique genetics and morphology. It is endemic to California, growing only in the northern Santa Lucia Mountains. Most bristlecone fir groves are small and scattered. Bristlecone fir requires a mild climate with minimal winter frost and relatively low summer evaporation rates. It prefers cool, moist sites and grows in a wide variety of soils. However, many groves are restricted to steep, rocky sites that rarely burn due to sparse fuels. Bristlecone fir also occurs in mixed-evergreen and mixed-conifer woodlands and forests, where it is most common in the canyon live oak phase of mixed-evergreen forests. It occurs in all stages of forest succession. Bristlecone fir groves can become dense and shaded in late succession.

Bristlecone fir has a narrow, spikey form and is usually no more than 100 feet tall at maturity. The thin spines on its cones, for which the species is named, are unique within the genus. Bristlecone fir establishes from seed. Seed production can be high; however, drought limits seedling establishment. Best establishment occurs in moist mineral soil. Genetic diversity is low for this species.

Bristlecone fir is easily killed by fire because it has thin bark, and the often low branches make it susceptible to ignition and torching. It establishes from wind- and animal-dispersed seeds after fire. It is primarily a fire avoider, usually growing on rocky sites with thin, poorly developed soils and sparse fuels. Information about fire effects and postfire recruitment of bristlecone fir was largely anecdotal as of 2020.

Fire regimes in bristlecone fir groves were not well known or documented as of 2020. Historical fire intervals were probably moderately long, with fires occurring from several decades to over 100 years apart. Fire scars analyses are difficult to impossible for bristlecone fir because the groves usually escape fire, and there is little information on historical fire frequencies in the groves. Historically, most lightning fires in the Santa Lucia Mountains were apparently small.


INTRODUCTORY



Citation:
Fryer, Janet L. 2020. Abies bracteata, bristlecone fir. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/plants/tree/abibra/all.html [].

Literature cited in this Species Review include these reviews: [16,46]. A dissertation by Talley (1974) provides original documentation of bristlecone fir ecology, and it is cited throughout this Species Review [59].

FEIS abbreviation:
ABIBRA

Common names:
bristlecone fir
Santa Lucia fir
silver fir

TAXONOMY
The scientific name of bristlecone fir is Abies bracteata (D. Don) D. Don ex Poit. (Pinaceae) [3,7,16,22,30,31,60,61]. Bristlecone fir is classified in either a monotypic subgenus (Pseudotorreya) or a section (Bracteatae) of Abies [13,17,20,64]. Genetically and morphologically, it has been called the most "non-conforming fir of its genus worldwide" [36]. It does not hybridize with other fir species [13].

Common names are used throughout this Species Review. See table A1 for a complete list of plant species mentioned in this review.

SYNONYMS
Abies venusta (Douglas) K. Koch (documented in [15,22,30,61])

LIFE FORM
Tree

DISTRIBUTION AND OCCURRENCE

SPECIES: Abies bracteata
GENERAL DISTRIBUTION
Figure 2—Bristlecone fir distribution. Map courtesy of the U.S. Department of the Interior, Natural Resources Conservation Service. [2020, May 22] [61].

Bristlecone fir is endemic to California (fig. 2). Its geographic range is extremely narrow; it occurs only in the northern Santa Lucia Mountains of central-coastal California, in Monterey County [7,22,41,47,60] and extreme northwestern San Luis Obispo County [26,41,51,56]. It is distributed 1.5 to 14 miles (2.5-22 km) from the coast, with most groves (wooded areas with little or no underbrush) situated 2.5 to 9 miles (4-15 km) inland [59]. It grows mostly on public land: it occurs across a narrow strip (55 × 13 miles (88 × 21 m)) in the Ventura Wilderness of the Los Padres National Forest and in U.S. Army's Fort Hunter [16,55]. It is the rarest fir in North America [16,26]. As of 2013, there were ~1,000 bristlecone fir trees on the Los Padres National Forest [46].

Bristlecone fir has been successfully planted in Mediterranean regions of Europe, but plantings in the northeastern United States have not been successful [16].

States: CA [61]

SITE CHARACTERISTICS AND PLANT COMMUNITIES
Terrain and plant communities in the Santa Lucia Mountains are complex and diverse. Rapid climate shifts along an elevational gradient, and complex geology and topography, result in plant community differences across short distances. The elevational difference of nearly 1 mile (1.6 km) within a 3-mile (5-km) distance; a variety of slope exposures and soil types; the influence of the cool marine layer at low elevations; the very steep gradient of precipitation; and a variety of slope exposures and soils create a very steep gradient of environments and plant communities from low to high elevations [11].

Site Characteristics: Bristlecone fir requires a mild climate with minimal winter frost and relatively low summer evaporation rates [2,54]. Climate in the Santa Lucia Mountains is mediterranean with a maritime influence [16,44,59]. Temperatures within bristlecone fir's narrow range are moderate, rarely below 0 or above 100 oF (-17 or 38 oC), although exposed ridges have wider fluctuations in temperature [44,47]. Annual precipitation averages 20 to 50 inches (500-1,300 mm) [16,59]. Rainfall is sparse from June through September (averages <2% of total) [59], and snowfall is uncommon [44,47].

Bristlecone fir grows at lower elevations than most firs [22]. Its overall range extends from 690 to 5,250 feet (210-1,600 m) [3,16,59,60]. In surveys across its range, more than half of bristlecone fir's distribution was above 3,280 feet (1,000 m) [40,59], with the highest elevational distribution on Cone Peak [16].

Bristlecone fir occurs on a variety of slope positions. It grows in relatively cool, moist canyons [9,16,29,39,47,51,55,56]; on terraces and ridges [9,55,56]; and on barren, steep, rocky sites [9,16,25,51,55,60]. Bristlecone fir is most common northerly or east-facing slopes [9,16,47,56,59], but it also grows on south- and southeast-facing slopes above 4,500 feet (1,400 m) [16,59]. On southerly sites and at low elevations, it almost always grows on relatively moist, sheltered sites [16]. Forest slopes supporting bristlecone fir groves average 25o; the steepest slopes are up to 44o. Large, open groves occur on steep slopes, although the largest groves occur on relatively level ridges and plateaus with deep, coarse soils [59]. Terrain of groves in sandstone soils is relatively flat [59]

Soils supporting bristlecone fir are highly variable, with a wide variety of substrates and soil textures [49]. They are largely derived from metamorphic (mostly granitic) parent materials in the northern portion of the Santa Lucia Mountains, but parent materials also include schist, gneiss, and marble [55,59]. Igneous and marine sediment parent materials, including basalt and sandstone, dominate the substrate of the southern portion of bristlecone fir's range [59]. It can grow in serpentine and other ultramafic parent materials [49]. Bristlecone fir usually grows in coarse soils, although it also grows in fine-textured soils (i.e., clay and loam) [56,59]. Soils are usually thin and poorly developed, although the largest individuals tend to grow in mixed-evergreen forests with deeper soils [28]. Pinchot (1908) reported that "where it makes its best growth the soil is usually porous and fairly deep, but near its upper altitudinal limit the tree often grows in shallow beds of coarse rock fragments" [47]. Soil pH ranges from very strongly acidic to mildly alkaline [52] (~4.5-7.8 pH).

Plant Communities: Bristlecone fir occurs in coastal temperate, mixed-evergreen and mixed-conifer woodlands and forests [22,28] and riparian woodlands [8]. Within these plant communities, it may grow in mixed stands or grow in distinct groves (small wooded or forested areas, usually with no undergrowth). Bristlecone fir is most likely to form pure stands at high elevations [47].

Bristlecone fir is most common in the canyon live oak [25,42,59] phase of mixed-evergreen sclerophyll forests [3,25,59,60]. At low elevations in mixed-evergreen forests, it also grows with coast live oak, Pacific madrone, tanoak, redwood, and/or Shreve oak [16,46,55,56], just above the redwood forest zone [26,59]. It fingers into the fog belt of redwood forests [6,16,26] and into chaparral [9,31]. At mid- to high elevations in mixed-evergreen forests, it grows with incense-cedar and interior live oak [2,27,55,56]. Associates in mixed-conifer forests include coast Douglas-fir, ponderosa pine, and sugar pine [2,9,16]. Commonly, pines are associates at highest elevations [39]. Coulter pine is an associate in the southern portion of bristlecone fir's distribution [4,16].

Although bristlecone fir groves usually have sparse understories, some shrubs and herbs cooccur. Understory species in bristlecone fir groves and surrounding vegetation include birchleaf mountain-mahogany, deerbrush, Eastwood's manzanita, pinkbracted manzanita [28], and nonnative French broom [8]. On rocky ridges and slopes, forb associates include Brewer's rockcress, coastal lipfern, hoary buckwheat, redwood keckiella, and rockloving erigeron. Western swordfern occurs in the understory of mesic ravine groves [45]. See table A2 for a representative list of plant classifications in which bristlecone fir occurs.

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Abies bracteata
GENERAL BOTANICAL CHARACTERISTICS
Botanical Description: This description covers characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available: [3,60].

Bristlecone fir is a medium-sized conifer [47]. It is typically 30 to 100 feet (10-30 m) tall at maturity [16,59], but some individuals reach 160 feet (50 m) tall [59]. Diameter at breast height is from 4 to 12 inches (10-30 cm); rarely, up to 40 inches (100 cm) [16,47]. The tallest individuals grow in deep ravines and on ocean-facing slopes. Stunted individuals grow on exposed, cold ridges and at high elevations [47]. For summit, transition, and ravine sites, mean heights of 100-year-old bristlecone firs were 40, 70, and 90 feet (12, 21, and 27 m), respectively [59]. The champion tree is 127 feet (39 m) tall, 150 inches (380 cm) in circumference, and 36 feet (11 m) in spread [1]. The bole of bristlecone fir is straight and limby, tapering rapidly [39,47], and the crown is narrow and spikey [2,16,47] (fig. 1). Branches may extend to the ground [3,16,22,39,60], and they become droopy with age. Bark is smooth and thin [2,16]; bark thickness measurements were lacking in the literature. Needles are 1.0 to 2.4 inches (2.5-6.0 cm) long [16,22,60]. Needles are unusually sharp [2,36], wide, and long [59] for a fir, and they have a strong, pungent odor [22,31]. Seed cones are <3.5 inches (9 cm) long [60]; usually, 1.6 to 2 inches (4-5 cm) long, and only occur in the top of the crown [36,59]. They are resinous [36,39] and covered with thin spines (bract scales, see fig. 3); hence, the common name "bristlecone fir". These spines are unique among Abies species [22]. Bristlecone fir is the only fir in which the bract scales extend far out from the cone scales [40]. Seeds are about 0.2 inch (5 mm) long. Seed wings are about as long as the seed [22].

Figure 3—Bristlecone fir seed cone. Image by Charles Webber, California Academy of Sciences. Used with permission.

Most bristlecone fir groves are small and scattered [10,14,36,47,59]; generally, they are <5 acres (2 ha) [10,14,47]. In 1908, Pinchot reported that no bristlecone fir groves contained more than 200 trees [47]. The canopy layer in bristlecone fir groves is usually continuous, the shrub layer open to intermittent, and the herbaceous layer sparse [9]. Groves are typically uneven-aged except at highest elevations, where even-aged structure predominates, probably due to rare wet years that favored synchronous establishment [59].

Bristlecone firs may live longer than 200 years [38].

Raunkiaer (1934) Life Form:
Phanerophyte [48]

SEASONAL DEVELOPMENT
Pollen cones emerge and mature in spring; they are yellow to yellowish-green when mature [22]. Seed cones require 2 years to mature, with cone buds developing the first year and cones maturing the second year [59]. Second-year cones expand from late April [13,16] to early May, and they disperse seeds and disintegrate from late August to October [16]. Seeds germinate in late fall and early winter [59].

REGENERATION PROCESSES

Pollination and Breeding System: Bristlecone fir is wind pollinated [38].

Successful reproduction requires outcrossing. Unsuccessful selfing is apparently high in bristlecone fir. For six populations across bristlecone fir's range, levels of inbreeding were high in seed embryos but not in mature trees, suggesting high rates of embryo and seedling death [38]. Genetic diversity of bristlecone fir is low compared to other California conifers [37,38], with low rates of within- and between-population genetic differentiation [38].

Seed Production: Pinchot (1908) reported bristlecone fir was a "moderately vigorous" seed producer [47]. Large cone crops are reported [25], with 3 to 5 years between large crops [17,47]. Large cone crops are usually followed by years of little to no cone production [59]. Larvae of fly [17,33,39], moth [33], and chalcid wasp [17,33,59] species reduce seed yields. Predispersal seed predation may near 100% in some years. Seed predator populations usually peak the year after a large cone crop [59]. Following that population peak, however, seed production and seed predator insect populations may remain out of phase for at least 3 years. Therefore, Talley (1974) [59] concluded that "claims that cone parasites are endangering the fir are not valid".

Production of viable seeds appears low, probably due to inbreeding. The study of six populations found production of filled seeds varied widely, ranging from an average of 18.6 seeds/cone in the Villa Creek population to 93.7 seeds/cone in the Cone Peak population (the largest population sampled). Total number of seeds/cone (filled and unfilled) ranged from 188.0 seeds/cone in the Cone Peak population to 255.4 seeds/cone in the Miller Canyon population [38].

Age at first seed production was not reported. Trees >100 years old continue to produce seeds [9]. Based on age class distributions, Talley (1974) estimated that for high-elevation groves, only one or two bristlecone firs/century reach cone-bearing age [59].

Seed Dispersal: Wind, gravity, and animals disperse the seeds [9].

Seed Banking: Bristlecone fir has a soil seed bank [17], although the length of time the seeds remain viable was not reported in the literature.

Even though cones ignite easily, seeds within unburned cones may survive surface fire [25].

Germination: Pinchot (1908) reported that germination rates appear low [47]. Observations suggest that highest germination rates occur in mineral soil [16,47]. Fresh seeds are germinable [17,59], but overwinter stratification improves germination rates [9,59]. In a field study, germination of planted seeds was low in exposed, steep, and/or high-elevation sites. Few or no seedlings emerged in annual grassland, chaparral, and summit mixed-conifer communities. Germination was highest (10%) at midelevations [59].

Seedling Establishment and Plant Growth: Pinchot (1908) wrote that seedling establishment "is fairly good throughout the range of the species" [47]; however, dry soils and drought limit bristlecone fir establishment. Open to lightly shaded, moist sites with mineral soil apparently favor bristlecone fir establishment. Talley (1973) noted that the greatest bristlecone fir establishment occurred in open redwood—mixed-evergreen forest ecotones, and seedlings in closed, mixed-evergreen forests did not survive to the sapling stage [59].

Limited evidence suggests that seedling mortality is high [38,59]. Bristlecone fir seedlings are drought-sensitive [40,59], and water stress greatly limits bristlecone fir establishment and growth. Field and laboratory experiments showed bristlecone fir establishment was positively correlated with light shade, warm winter and spring temperatures, low summer temperatures, northerly slopes, and fine-grained soils. Ravine and ravine-midelevation transition sites supported more bristlecone firs of all age classes than terraces and high-elevation sites (P < 0.05 for all variables). These variables were most likely to coincide in mixed-evergreen forests in the canyon live oak phase [59]. Talley (1974) found most seeds planted on annual grassland, chaparral, and summit forest sites failed to establish, which he attributed to desiccation of germinants. However, bristlecone fir established from seeds planted on low-elevation coastal canyon sites and on a site that had burned the previous year. Seedlings at highest elevations required shade to establish [59].

Bristlecone fir grows fastest on fine-grained soils (i.e., those with high water-holding capacity). However, because bristlecone firs on these soils are more susceptible to fire than those on coarse-grained soils (see Fire Adaptations and Plant Response to Fire), groves on fine-grained soils are rare [59]. Talley (1974) concluded that fire and deep shade limit growth to the sapling stage at low elevations, while drought limits bristlecone fir seedling establishment at high elevations [59].

Vegetative Regeneration: Firs do not naturally reproduce vegetatively [17].

SUCCESSIONAL STATUS:
Bristlecone fir occurs in all stages of forest succession. All age classes of bristlecone fir are shade tolerant [47], although seedlings in moist soils tolerate and apparently prefer open sites [59]. Bristlecone fir establishes in chaparral on some sites [9], and it occurs in canyon live oak woodlands that are succeeding to mixed-evergreen forest [60]. Bristlecone fir groves can become dense and shaded in late succession [52].

FIRE EFFECTS AND MANAGEMENT

SPECIES: Abies bracteata
FIRE EFFECTS

Immediate Fire Effects on Plant

Fire usually kills bristlecone fir [9,16,28,59,63] because it has thin bark [2,16]. The low branches make it susceptible to ignition and torching [2,9,16,40]. Surface fire of even low severity kills seedlings, but saplings may survive low-severity surface fire [59]. Trees in some mature groves have survived surface fires [25,59], (Kwasny, Los Padres National Forest, personal communication cited in [55,56]) of apparently moderate severity and bear fire scars [59]. Severe surface or crown fire kills bristlecone firs of all age classes [2,14,21,25,39]. Bristlecone firs at grove-forest ecotones are killed when fire transitions from surface to crown fire [59].

The widely scattered pattern of bristlecone fir groves is attributed to fire mortality across the landscape [16]. Severe fire may remove entire bristlecone fir groves from a site [25]. In the 1977 Marble Cone Fire on the Los Padres National Forest, most bristlecone firs survived because they were growing on steep, rocky slopes with light fuel loads that did not burn. Nearly all bristlecone firs on the edges of canyon live oak communities were killed, but the largest tree (52 inches (132 cm) diameter) survived "with no damage" [25].

The resinous seed cones ignite easily, likely killing the seeds within [39]. Seeds within unburned cones may survive surface fire [25].

Postfire Regeneration Strategy [57]

Tree without adventitious buds and without a sprouting root crown

These postfire regeneration strategies are likely, although they are not well documented:
Crown residual colonizer (on site, initial community)
Initial off-site colonizer (off site, initial community)
Secondary colonizer (on- or off-site seed sources)

Fire Adaptations and Plant Response to Fire

Bristlecone fir establishes from wind- and animal-dispersed seeds after fire [59]. Surveys of postfire seedling establishment of bristlecone fir had not been conducted as of 2020. However, Griffin (1978) postulated that bristlecone fir may establish from viable crown-stored seeds after surface fire, even if fire killed the parent trees [25]. Talley (1974) observed that seed production and seedling establishment following the 1970 Buckeye Fire was "excellent" [59].

Bristlecone fir is primarily a fire avoider, often growing on rocky sites with thin, poorly developed soils and sparse fuels [9,14,26,28,44,56,59]. Based on field surveys and Forest Service, U.S. Department of Agriculture fire records, Talley (1974) found that basal area of bristlecone fir was positively associated with sites showing little or no evidence of fire; with steep, fuel-limited, rocky sites; and with fine-grained soils (P < 0.05). He found that 54% of the variance in bristlecone fir basal area was correlated with fire severity (P < 0.0001) [59]. Fire effects to and response of bristlecone firs growing in relatively moist canyon bottoms was not addressed in the literature as of 2020.

Fire effects to and postfire recruitment of bristlecone fir were largely anecdotal as of 2020. In the 1970 Buckeye Canyon Fire, Talley (1974) noted that although surrounding mixed-evergreen forest experienced crown fire, the Spruce Fork grove experienced only surface fire, and mature bristlecone firs showed only "minor, local damage". The steepest slopes showed no evidence of fire, and bristlecone fir saplings on those slopes were undamaged [59]. Although the 1985 Rat Creek-Gorda Fire burned most of the Cone Peak Gradient Research Natural Area [32], most mature bristlecone fir in the area survived. Following the 2008 Basin Complex Fires, surveys in postfire years 5 and 6 found dead bristlecone firs in burned areas, with the highest mortality in the Ventana Double Cone grove. Surveyors noted some postfire bristlecone fir recruitment in two groves (California Natural Diversity Database 2017 data cited in [46]). In the 2016 Soberanes Fire, most bristlecone firs within the fire perimeter survived [46].

Griffin (1978) noted that many bristlecone firs escaped the 1977 Marble Cone Fire. The fire was mostly stand-replacing due to a large accumulation of dead brush and other fuels. However, most bristlecone fir groves were on steep, rocky terrain that did not carry the fire; only trees on the edges of the groves were killed. The largest bristlecone fir in the area (51 inches (129.5 cm) in diameter) appeared undamaged 10 months after the fire [25].

Anecdotal evidence suggests that postfire insect infestations kill more bristlecone firs than fires [46,59]. Griffin (1978) noted insect mortality of bristlecone firs that survived the Marble Cone Fire, and he suspected that insect damage would eventually kill more bristlecone firs than the fire. He based this supposition on the work of Talley (1974), who observed that two bristlecone fir groves lost only a small number of trees as a direct effect of the 1970 Buckeye Fire, but they had higher mortality rates as a result of "postfire insect damage [59]". Griffin (1978) speculated that although "some additional trees will die, ... the species and even individual groves are in no way doomed" [25].

FUELS AND FIRE REGIMES

Fuels

While bristlecone fir occurs on many slope positions (see Site Characteristics), large groves often occupy steep, rocky slopes that have sparse fuels [9,14,25,26,59,60]. It also occurs in canyon bottoms that may be too moist to burn in some years [60]. Talley (1971) wrote that "Large groves of fir are always in regions of precipitous cliffs or steep-rugged canyons which are steep enough to prevent litter accumulation extensive enough to carry a strong fire...The Buckeye Canyon fire of Sep 1970 presented a vivid example of how this tree is restricted by fire. This fire was one of the hottest, certainly the largest, of several decades. Whole slopes were completely "cleaned off", while the two fir groves in the burn received only ground (i.e., surface) fires, or didn't burn at all" (Talley 1971, cited in [59]). He observed that while surrounding mixed-evergreen forest experienced crown fire, the Spruce Fork grove experienced only surface fire, and the steepest slopes showed no evidence of fire [59]. He concluded that "the boundaries of Santa Lucia fir (i.e., bristlecone fir) groves are primarily determined by topography which excludes hot fires" [59].

Surface fuels in bristlecone fir groves are mainly dry grass and tree litter. However, because bristlecone fir has a narrow form and low branches, it can become a ladder fuel [59].

Sudden Oak Death was first noted in the Santa Lucia Mountains in the 1990s. It is caused by an oomycete (Phytophthora ramorum). As it spreads, it has had myriad ecological effects to the mixed-evergreen forests, including changes in stand structure and increasing standing dead and woody debris fuels. It infects coast live oak, Shreve oak, and tanoak [43,46].

Fire Regimes

Summary: Fire regimes in bristlecone fir groves are not well known or documented. Before Spanish settlement of the Monterey Bay area in the 1770s, most fires in the Santa Lucia Mountains were probably lightning caused. Most fires in bristlecone fir groves at high elevations were likely small and of low severity due to sparse fuels, but groves at midelevations may have also experienced moderate- and high-severity fires. Fire intervals were probably moderately long, with fires occurring from several decades to over 100 years apart. In this Species Review, "historical" refers to the period prior to Spanish settlement of the Monterey Bay region in the 1770s.

Lightning fires occur throughout the Monterey Bay region from May to October [9,24]. Fuels are driest from June to July and from September to October, making ignition most probable during these periods [24]. Although historical fire sizes in the area are not well documented, most lightning fires in the Santa Lucia Mountains were apparently small [9,59], and they typically did not consume entire bristlecone fir groves [9]. However, some fires probably grew large; for example, a 1916 wildfire burned 7,000 acres (2,800 ha) in the Santa Lucia Mountains [24,25]). Fires may be of low [59], mixed, or high severity in bristlecone fir groves [9]. Fire intensity in bristlecone fir groves had not been quantified as of 2020.

It is unclear how American Indian-set fires affected presettlement fire regimes in the Santa Lucia Mountains [44]. When Spanish entered the area, the Monterey Bay region supported one of the densest aboriginal populations in North America. The American Indian population may have reached 26,000 in the area. However, there is no evidence that American Indians actively set fires in the Santa Lucia Mountains; the area mostly inaccessible because it is so steep and rugged [12].

Historical fire intervals were not documented for bristlecone fir groves as of 2020, but intervals are estimated at several decades to >100 years. Fire scars analyses are difficult to impossible because bristlecone fir groves usually escape fire or succumb to fire, so there is little information on historical fire frequencies in the groves [44]. Age class analyses of bristlecone fir, which could provide information on time-since-fire, had not been conducted as of 2020. In a review of 35 studies, fire intervals are estimated at 117 (mean), 93 (median), 90 (mean minimum), and 250 (mean maximum) years for fire-sensitive fir communities, including bristlecone fir. However, 80% of these studies were conducted in areas outside of California, and none were specific to bristlecone fir groves [63]. In the Santa Lucia Mountains, fire intervals ranged from 19 to 78 years, based on fire scars on sugar pines (time interval: 1640-1977). However, fire intervals for bristlecone fir groves on steep slopes with sparse fuels are probably longer than that. For mixed-evergreen forests of the Monterey Bay region, fire intervals are estimated at 30 to 135 years in historical times and a mean of 250 years in the 1990s [58]. For redwood forests, mean fire intervals are estimated at 135 years in historical times and 130 years in the 1990s [24]. These estimates are based on fire scar data, fire records, and modeling [24,58]. The California Native Plant Society (2020) estimated fire intervals of 50 to 100 years for bristlecone fir groves [9], but the basis for their estimate was not stated. LANDFIRE (2009) modeled fire intervals in mixed-evergreen forests of this region as mostly surface fires (81% of all fires), with a mean fire interval of 9 years and ranging from 5 to 30 years [35].

While estimates of contemporary fire intervals in bristlecone fir groves are lacking, fire records document several fires in the Santa Lucia Mountains from the 1930s onward. From 1931 to 1977, 39 lightning fires occurred in the Monterey County portion of the Santa Lucia Mountains [58,59]. From the 1970s to the 2010s, a series of mostly lightning-ignited fires burned in the Santa Lucia Range: the 1970 Buckeye Canyon (human-caused), 1977 Marble Cone, 1985 Rat Creek-Gorda, 1996 Wild Cattle, 1999 Kirk Complex, 2008 Basin Complex, and 2016 Soberanes fires (CalFire 2016 data cited in [46]). The fire interval for this period averages 7.7 years.

Find further fire regime information for the plant communities in which this species may occur by entering "bristlecone fir" on the FEIS home page.

FIRE MANAGEMENT CONSIDERATIONS

It is uncertain whether the fire regime has changed in bristlecone fir groves since historical times. Some speculate that since the mid-twentieth century, intense, large fires have recurred in the Santa Lucia Mountains at shorter intervals than in the preceding several hundred years [9,14]. However, limited evidence suggests that contemporary wildfires are not burning very far into bristlecone fir groves. Furthermore, Talley (1974) stated that based on observations and Forest Service fire records, there were few differences between past and present fire intensities within bristlecone fir groves despite changing fire regimes in adjacent plant communities [59].

Because postfire response of bristlecone fir has not been studied systematically, the California Native Plant Society (2016) recommends that the “spatial turnover of stands” be examined from repeat aerial photography. This is especially important as fire regimes change in response to climatic change and anthropogenic activities (California Native Plant Society 2016, cited in [46]).

MANAGEMENT CONSIDERATIONS

SPECIES: Abies bracteata
FEDERAL LEGAL STATUS
None [62]

OTHER STATUS
The California Native Plant Society (2020) ranks bristlecone fir as a rare plant (1B.3) that is imperiled and/or vulnerable both state-wide (S2S3) and globally (G2S2), due to its extremely limited distribution [8]. NatureServe (2020) ranks the species as imperiled (G2), and the bristlecone fir forest alliance as vulnerable (G3) [45]. Further information on state-level protection status of plants in the United States and Canada is available at NatureServe.

IMPORTANCE TO WILDLIFE AND LIVESTOCK
Bristlecone fir provides food and shelter to birds, squirrels, and other small mammals [1,52]. Firs in general provide food and shelter for a variety of birds and mammals [17].

Palatability and Nutritional Value: Western grey squirrels eat bristlecone fir seeds, as do fly, moth, and chalcid wasp seed predators [33,59]. The sharply-pointed foliage is not palatable to mule deer [52] and likely, not to other potential browsers. Lanner (1999) reports that the "blade-thin and dagger-tipped" needles "easily pierce the skin of an impetuous foliage grasper" [36].

Cover Value: Birds and small mammals use bristlecone fir for cover [1].

VALUE FOR RESTORATION OF DISTURBED SITES
Bristlecone fir provides watershed protection [1,47] by reducing soil erosion and slowing water runoff. It is commercially available, although hard to obtain in some years [7]. Bristlecone fir seeds are stored in a laboratory seed bank for species conservation [5].

If outplanting is deemed necessary, Ledig et al. (2006) recommend collecting seeds from as many populations as possible, but concentrating seed collection in the two largest and most genetically diverse populations [38]:

"...among the populations sampled, Cone Peak is one of the best candidates for ex situ conservation and use as a seed source for restoration. The maximum number of alleles and polymorphic loci were found in Cone Peak and, to a lesser degree, Big Sur. No novel alleles were found in other populations. Furthermore, the greatest number of sound seeds per cone was found at Cone Peak and it is the most accessible population of Santa Lucia fir. Nevertheless, a cautious approach would ensure that multiple populations were conserved ex situ" [38].

OTHER USES
Bristlecone fir is not harvested for timber [38,59]. The wood is moderately soft, coarse-grained, and heavy [59]. Descriptions of bristlecone fir wood (e.g., specific gravity and cell structure) are available: [18,51].

Bristlecone fir is sometimes planted as an ornamental in areas with mild climates [59].

OTHER MANAGEMENT CONSIDERATIONS
The California Native Plant Society (2020) [8] states that bristlecone fir is threatened by nonnative plant species. French broom, a nonnative shrub, interferes with bristlecone fir seedling establishment and growth (Kwasny, Los Padres National Forest, personal communication cited in [55,56]), and may increase surface fuel loads in bristlecone fir groves.

Because bristlecone fir seedlings are drought-sensitive, an increasingly arid climate would likely reduce bristlecone fir regeneration, shrinking the already extremely narrow range of this endemic species [46]. Bristlecone fir's geographic range has been shrinking since the Miocene, as the climate became more arid [2,36,38,40,49,50]. Ledig et al. (2006) concluded that bristlecone fir's "limited range and fragmented distribution are the result of long-term geoclimatic changes, not human exploitation or human-mediated habitat loss. Nevertheless, it could be endangered by further anthropogenic warming". They consider its low genetic diversity, coupled with climate warming, the biggest obstacles to bristlecone fir conservation [38].

APPENDIX

SPECIES: Abies bracteata
Table A1—Common and scientific names of plant species mentioned in this Species Review. Links go to other FEIS Species Reviews.
Common name Scientific name
Ferns
western swordfern Polystichum munitum
Forbs
Brewer's rockcress Arabis breweri
coastal lipfern Cheilanthes intertexta
rockloving erigeron Erigeron petrophilus
hoary buckwheat Eriogonum saxatile
redwood keckiella Keckiella corymbosa
Shrubs
birchleaf mountain-mahogany Cercocarpus montanus var. glaber
Eastwood's manzanita Arctostaphylos glandulosa
deerbrush Ceanothus integerrimus
French broom Genista monspessulana
pinkbracted manzanita Arctostaphylos pringlei subsp. drupacea
Trees
bristlecone fir Abies bracteata
canyon live oak Quercus chrysolepis
coast Douglas-fir Pseudotsuga menziesii var. menziesii
coast live oak Quercus agrifolia
Coulter pine Pinus coulteri
incense-cedar Calocedrus decurrens
firs Abies spp.
interior live oak Quercus wislizeni
Pacific madrone Arbutus menziesii
ponderosa pine Pinus ponderosa var. benthamiana,
P. ponderosa var. ponderosa
redwood Sequoia sempervirens
Shreve oak Quercus parvula var. shrevei
sugar pine Pinus lambertiana
tanoak Notholithocarpus densiflorus

Table A2—Representative plant community classifications in which bristlecone fir occurs.
FRES Ecosystems [23]
FRES 20 Douglas-fir
FRES 27 Redwood
FRES 28 Western hardwoods
FRES 34 Chaparral-mountain shrub
Kuchler Plant Associations [34]
K005 Mixed conifer forest
K006 Redwood forest
K030 California oakwoods
K033 Chaparral
SAF Cover Types [19]
232 Redwood
234 Douglas-fir-tanoak-Pacific madrone
249 Canyon live oak
255 California coast live oak
SRM (Rangeland) Cover Types [53]
202 Coast live oak woodland
203 Riparian woodland

REFERENCES:


1. American Forests. 2020. Bristlecone fir (Abies bracteata). In: Champion trees national register, [Online]. Washington, DC: American Forests (Producer). Available: http://www.americanforests.org/explore-forests/americas-biggest-trees/champion-trees-national-register/ [2020, May 20]. [94260]
2. Axelrod, Daniel I. 1976. Evolution of the Santa Lucia fir (Abies bracteata) ecosystem. Annals of the Missouri Botanical Gardens. 63(1): 24-41. [22018]
3. Baldwin, Bruce G.; Goldman, Douglas H.; Keil, David J.; Patterson, Robert; Rosatti, Thomas J.; Wilken, Dieter H., eds. 2012. The Jepson manual. Vascular plants of California, second edition. Berkeley, CA: University of California Press. 1568 p. [86254]
4. Barbour, Michael G. 1987. Community ecology and distribution of California hardwood forests and woodlands. In: Plumb, Timothy R.; Pillsbury, Norman H., technical coordinators. Proceedings of the symposium on multiple-use management of California's hardwood resources; 1986 November 12-14; San Luis Obispo, CA. Gen. Tech. Rep. PSW-100. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station: 18-25. [5356]
5. Birker, Cheryl; Meyer, Evan. 2020. Seed conservation of Abies bracteata at Rancho Santa Ana Botanic Garden. In: CPC Rare Plant Academy, [Online]. Claremont, CA: Rancho Santa Ana Botanic Garden (Producer). Available: https://academy.saveplants.org/node/33 [2020, May 20]. [94261]
6. Borchert, Mark; Segotta, Daniel; Purser, Michael D. 1988. Coast redwood ecological types of southern Monterey County, California. Gen. Tech. Rep. PSW-107. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 27 p. [10225]
7. Calflora. 2020. The Calflora database: Information on California plants for education and conservation, [Online]. Berkeley, CA: Calflora (Producer). Available: http://www.calflora.org/. [76012]
8. California Native Plant Society, Rare Plant Program. 2020. Inventory of rare and endangered plants of California, [Online]. Edition v8-03 0.39. Sacramento, CA: California Native Plant Society (Producer). Available: http://www.rareplants.cnps.org [2020, May 22]. [94269]
9. California Native Plant Society. 2020. A manual of California vegetation, [Online]. Sacramento, CA: California Native Plant Society, Vegetation Program (Producer). Available: http://www.cnps.org/cnps/vegetation/ [2020, May 18]. [94257]
10. Canon, W. A. 1914. Specialization in vegetation and in environment in California. Plant World. 17: 223-237. [68590]
11. Cheng, Sheauchi, ed. 2004. Forest Service Research Natural Areas in California. Gen. Tech. Rep. PSW-GTR-188. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 338 p. [88290]
12. Cook, S. F. 1978. Historical demography. In: Heizer, Robert F., ed. Handbook of North American Indians. Vol. 8. Washington, D.C.: Smithsonian Institute: 91-99. [94258]
13. Critchfield, William B. 1988. Hybridization of the California firs. Forest Science. 34(1): 139-151. [22019]
14. Davis, Frank W.; Borchert, Mark I. 2006. Central Coast bioregion. In: Sugihara, Neil G.; van Wagtendonk, Jan W.; Shaffer, Kevin E.; Fites-Kaufman, Joann; Thode, Andrea E., eds. Fire in California's ecosystems. Berkeley, CA: University of California Press: 321-349. [65548]
15. Dayton, William A. 1952. Notes on United States tree names: Bristlecone fir. Rhodora. 54: 74-76. [21758]
16. Earle, Christopher J., ed. 2020. Abies bracteata. In: The Gymnosperm Database, [Online]. Christopher J. Earle (Producer). Available: https://www.conifers.org/pi/Abies_bracteata.php [2020, May 5]. [94249]
17. Edwards, D. George W. 2008. Abies P. Mill.: fir. In: Bonner, Franklin T.; Karrfalt, Robert P., eds. Woody plant seed manual. Agric. Handbook No. 727. Washington, DC: U.S. Department of Agriculture, Forest Service: 149-198. [79011]
18. Esteban, Luis Garcia; de Palacios, Paloma; Fernandez, Francisco Garcia; Moreno, Ruth. 2009. Wood anatomy of the genus Abies: A review. IAWA Journal. 30(3): 231-245. [94263]
19. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905]
20. Farjon, A.; Rushforth, K. D. 1989. A classification of Abies Miller (Pinaceae). Notes from the Royal Botanic Garden, Edinburgh. 46(1): 59-79. [94264]
21. Fites-Kaufman, Joann; Bradley, Anne F.; Merrill, Amy G. 2006. Fire and plant interactions. In: Sugihara, Neil G.; van Wagtendonk, Jan W.; Shaffer, Kevin E.; Fites-Kaufman, Joann; Thode, Andrea E., eds. Fire in California's ecosystems. Berkeley, CA: University of California Press: 94-117. [65534]
22. Flora of North America Editorial Committee, eds. 2020. Flora of North America north of Mexico, [Online]. Flora of North America Association (Producer). Available: http://www.efloras.org/flora_page.aspx?flora_id=1. [36990]
23. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; Lewis, Mont E.; Smith, Dixie R. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [998]
24. Greenlee, Jason M.; Langenheim, Jean H. 1990. Historic fire regimes and their relation to vegetation patterns in the Monterey Bay area of California. The American Midland Naturalist. 124(2): 239-253. [15144]
25. Griffin, James R. 1978. The Marble-Cone fire ten months later. Fremontia. 6: 8-14. [19081]
26. Griffin, James R.; Critchfield, William B. 1972. The distribution of forest trees in California. Res. Pap. PSW-82. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 118 p. [1041]
27. Gutierrez, R. J.; Koenig, Walter D. 1978. Characteristics of storage trees used by acorn woodpeckers in two California woodlands. Journal of Forestry. 76(3): 162-164. [20555]
28. Holland, Robert F. 1986. Preliminary descriptions of the terrestrial natural communities of California. Sacramento, CA: California Department of Fish and Game. 156 p. [12756]
29. Howitt, Beatrice F.; Howell, John Thomas. 1964. The vascular plants of Monterey County, California. Wasmann Journal of Biology. 22(1): 1-184. [22168]
30. ITIS Database. 2020. Integrated taxonomic information system, [Online]. Available: http://www.itis.gov/index.html. [51763]
31. Kartesz, J. T. The Biota of North America Program (BONAP). 2015. Taxonomic Data Center, [Online]. Chapel Hill, NC: The Biota of North America Program (Producer). Available: http://bonap.net/tdc [Maps generated from Kartesz, J. T. 2010. Floristic synthesis of North America, Version 1.0. Biota of North America Program (BONAP). [in press]. [84789]
32. Keeler-Wolf, Todd. 1990. Ecological surveys of Forest Service Research Natural Areas in California. Gen. Tech. Rep. PSW-GTR-125. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 177 p. [94285]
33. Keen, F. P. 1958. Cone and seed insects of western forest trees. Tech. Bull. 1169. Berkeley, CA: U.S. Department of Agriculture, Forest Service, California Forest and Range Experiment Station. 168 p. [94266]
34. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation of the conterminous United States. Special Publication No. 36. New York: American Geographical Society. 166 p. [1384]
35. LANDFIRE Biophysical Settings. 2009. Biophysical setting 0310270: Mediterranean California dry-mesic mixed conifer forest and woodland. In: LANDFIRE Biophysical Setting Model: Map zone 03, [Online]. In: Vegetation Dynamics Models. In: LANDFIRE. Washington, DC: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory; U.S. Geological Survey; Arlington, VA: The Nature Conservancy (Producers). Available: https://www.landfire.gov/national_veg_models_op2.php [2020, May 2]. [94283]
36. Lanner, Ronald M. 1999. Conifers of California. Los Olivos, CA: Cachuma Press. 274 p. [30288]
37. Ledig, F. Thomas. 1987. Genetic structure and the conservation of California's endemic and near-endemic conifers. In: Elias, Thomas S., ed. Conference on the conservation and management of rare and endangered plants: Proceedings of a California conference on the conservation and management of rare and endangered plants; 1986 November 5-8; Sacramento, CA. Sacramento, CA: California Native Plant Society: 587-594. [22218]
38. Ledig, F. Thomas; Hodgskiss, Paul D.; Johnson, David R. 2006. Genetic diversity and seed production in Santa Lucia fir (Abies bracteata), a relict of the Miocene broadleaved evergreen forest. Conservation Genetics. 7(3): 383-398. [94253]
39. Legg, Ken. 1953. Bristlecone fir makes its last stand. Nature Magazine. 46(10): 521-522. [22167]
40. Leopold, Estella B.; Zaborac-Reed, Stephanie. 2014. Biogeographic history of Abies bracteata (D. Don) Poit. in the western United States. In: Stevens, W. D.; Montiel, Olga Martha; Raven, Peter H., eds. Paleobotany and biogeography: A Festschrift for Alan Graham in his 80th year. Monograms in Systematic Botany. 28. St. Louis, MO: Missouri Botanical Garden Press: 252-286. [94267]
41. Little, Elbert L., Jr. 1975. Rare and local conifers in the United States. Conservation Research Report. No. 19. Washington, DC: U.S. Department of Agriculture, Forest Service. 25 p. [15691]
42. Mallory, James I. 1980. Canyon live oak. In: Eyre, F. H., ed. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters: 125-126. [7608]
43. Meentemeyer, R. K.; Rank, N. E.; Shoemaker, D. A.; Oneal, C. B.; Wickland, A. C.; Frangioso, K. M.; Rizzo, D. M. 2008. Impact of sudden oak death on tree mortality in the Big Sur ecoregion of California. Biological Invasions. 10: 1243-1255. [73493]
44. Minnich, Richard A. 1988. The biogeography of fire in the San Bernardino Mountains of California: A historical study. University of California publications in geography: Volume 28. Berkeley, CA: University of California Press. 161 p. [69040]
45. NatureServe. 2020. NatureServe Explorer, [Online]. Arlington, VA: NatureServe (Producer). Available: http://explorer.natureserve.org/. [FEIS id: 94379]
46. Nedeff, Nikki. 2011. Abies bracteata: Endangered, [Online]. In: Endangered species fact sheets. Watsonville, CA: National Estuarine Research Reserve System, Coastal Training Program (Producer). Available: http://www.elkhornsloughctp.org/factsheet/factsheet.php?SPECIES_ID=100 [2020, June 1]. [94281]
47. Pinchot, Gifford. 1908. Bristle-cone fir, Abies venusla (Dougl.) Koch. Silvicultural leaflet 24. Washington, D.C.: U.S. Department of Agriculture, Forest Service. 2 p. [94256]
48. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford, England: Clarendon Press. 632 p. [2843]
49. Raven, Peter H.; Axelrod, Daniel I. 1978. Origin and relationships of the California flora. University of California Publications in Botany. Volume 72. Berkeley, CA: University of California Press. 134 p. [61422]
50. Rundel, Philip W. 2019. A Neogene heritage: Conifer distributions and endemism in mediterranean-climate ecosystems. Frontiers in Ecology and Evolution. 27: 1-19. [94254]
51. Sargent, Charles S. 1984. Report on the forests of North America. Washington, D.C.: U.S. Government Printing Office. 612 p. [+ map]. [90894]
52. SelecTree. 2020. Santa Lucia fir tree record, 1995-2020. In: SelecTree: A tree selection guide, [Online]. San Luis Obispo, CA: Urban Forests Ecosystem Institute (Producer). Available: https://selectree.calpoly.edu/tree-detail/abies-bracteata [2020, May 20]. [94259]
53. Shiflet, Thomas N., ed. 1994. Rangeland cover types of the United States. Denver, CO: Society for Range Management. 152 p. [23362]
54. Silen, Roy R.; Olson, Donald L. 1992. A pioneer exotic tree search for the Douglas-fir region. Gen. Tech. Rep. PNW-GTR-298. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 44 p. [21668]
55. Stephenson, John R.; Calcarone, Gena M. 1999. Mountain and foothills ecosystems. In: Southern California mountains and foothills assessment: Habitat and species conservation issues. Gen. Tech. Rep. PSW-GTR-172. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 15-60. [35514]
56. Stephenson, John R.; Calcarone, Gena M. 1999. Southern California mountains and foothills assessment. Gen. Tech. Rep. PSW-GTR-172. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. 402 p. [35525]
57. Stickney, Peter F. 1989. Seral origin of species comprising secondary plant succession in northern Rocky Mountain forests. FEIS workshop: Postfire regeneration. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. 10 p. [20090]
58. Talley, Steven N.; Griffin, James R. 1980. Fire ecology of a montane pine forest, Junipero Serra Peak, California. Madrono. 27(2): 49-60. [4788]
59. Talley, Steven Neal. 1974. The ecology of Santa Lucia fir (Abies bracteata), a narrow endemic of California. Durham, NC: Duke University. 208 p. Dissertation. [23160]
60. The Jepson Herbarium. 2020. Jepson online interchange for California floristics, [Online]. In: Jepson Flora Project. Berkeley, CA: University of California, The University and Jepson Herbaria (Producers). Available: http://ucjeps.berkeley.edu/interchange.html [70435]
61. USDA, NRCS. 2020. The PLANTS Database, [Online]. Greensboro, NC: U.S. Department of Agriculture, Natural Resources Conservation Service, National Plant Data Team (Producer). Available: https://plants.usda.gov/. [34262]
62. USDI, Fish and Wildlife Service. 2020. Endangered Species Program, [Online]. U.S. Department of the Interior, Fish and Wildlife Service (Producer). Available: https://www.fws.gov/endangered/. [86564]
63. Van de Water, Kip M.; Safford, Hugh D. 2011. A summary of fire frequency estimates for California vegetation before Euro-American settlement. Fire Ecology. 7(3): 26-58. [85190]
64. Xiang, Qiao-Ping; Xiang, Qiu-Yun (Jenny); Guo, Yan-yan; Zhang, Xian-Chun. 2009. Phylogeny of Abies (Pinaceae) inferred from nrITS sequence data. Taxon. 58(1): 141-152. [94268]

FEIS Home Page