Foliage of thinleaf huckleberry is of low flammability, allowing for survival after low severity fires, with top-kill resulting from higher severity fires. Top-killed plants sprout from rhizomes.
The clonal habit of thinleaf huckleberry favors ecotypic variation among populations. Plants subjected to regular fire intervals may be better suited to surviving fire than individuals developed under fire suppression [32]. Plants are consumed by fire only when adequate fuels are present to dry and preheat stems and foliage. Seed is not an important postfire recolonization method and is rarely found in postfire areas [106].
Historically, burning of thinleaf huckleberry patches by Native Americans was a regular activity in the subalpine zone of the Cascade and Pacific ranges. To enhance production, fires were set in autumn after berry harvest. Fires reduced invasion of shrubs and trees [17]. Fields of thinleaf huckleberry in the Pacific Northwest are considered a product of uncontrolled wildfires occurring before effective fire suppression [111].
FIRE REGIMES:
Western Montana: Cool habitats dominated by lodgepole pine, with thinleaf huckleberry as a plentiful understory species, showed high severity (stand replacing) fire return intervals of 150 to 250 years in past centuries [55]. Lower subalpine stands in the Bitterroot National Forest, including stands in the Douglas-fir/thinleaf huckleberry habitat type, common beargrass phase, showed mean intervals between surface fires ranging from 17 to 28 years with a range of 3 to 67 years. At lower elevations, on montane slopes including stands in the Douglas-fir/thinleaf huckleberry habitat type, mean fire return intervals ranged from 7 to 19 years with a range of 2 to 48 years [6]. About 60% of mature subalpine fir/common beargrass stands in western Montana show evidence of surface fire [7].
Northern Idaho: Dry, lower subalpine fir habitat types where thinleaf huckleberry occurs show historic intervals between low to moderate severity fires averaging 35 years. Stand replacing fires occurred at average intervals >217 years. Severe fires occurred at intervals of 60 to 70 years in cold, dry grand fir habitats where thinleaf huckleberry is a dominant species [135].
Mixed conifer forests of the grand fir series within the Elkhorn Mountains of Oregon showed historic fire return intervals of 50-200 years on sites where thinleaf huckleberry is the dominant understory species [2]. The Douglas-fir forests of the eastern Cascade Range possess longer fire return intervals and higher fire intensities where big huckleberry is present than where thinleaf huckleberry does not occur [164].
The following table provides some fire-return intervals where thinleaf huckleberry is found. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Community or Ecosystem Dominant Species Fire Return Interval Range (years) silver fir-Douglas-fir Abies amabilis-Pseudotsuga menziesii var. menziesii > 200 grand fir Abies grandis 35-200 western larch Larix occidentalis 25-100 Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to > 200 whitebark pine* Pinus albicaulis 50-200 Sierra lodgepole pine* Pinus contorta var. murrayana 35-200 Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 Rocky Mountain ponderosa pine* Pinus ponderosa var. scopulorum 2-10 Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [21] coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [8,114,128] California mixed evergreen Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii 35 western redcedar-western hemlock Thuja plicata-Tsuga heterophylla > 200 western hemlock-Sitka spruce Tsuga heterophylla-Picea sitchensis > 200 mountain hemlock* Tsuga mertensiana 35 to > 200 [21] *Fire-return interval varies widely; trends in variation are noted in the Species Review.In most areas, fire exclusion reduces thinleaf huckleberry populations over time. In Washington, a thinleaf huckleberry field of 8,000 acres (3,238 ha) within an old burn has diminished to 2,500 acres (1,012 ha), replaced by trees and brush after 40 years of fire exclusion [107]. Repeated low severity burns may control competing vegetation, enhancing thinleaf huckleberry vigor [109]. Franklin and Dyrness [51] attribute occurrence of widespread big huckleberry fields within the southern Washington Cascades to large and repeated wildfire.
The Gitxsan and Wet'suwet'en people of northwestern British Columbia used fire to manage thinleaf huckleberry fields. Burning typically occurred in the early fall, late August, and September. Late fall burns were specifically chosen to reduce fire severity and spread since fall frontal storm systems were likely to bring precipitation. Elders (women) decided burning time and scheduled fires during times they felt were prior to rainfall. Intervals between burns varied [82]. Sahaptin and Chinook Native Americans started fires in the fall (end of huckleberry season) during periods when winter rains had begun [54].
In habitat types were thinleaf huckleberry is dominant, fires conducted when duff is relatively moist and not completely consumed result in heavy sprouting from rhizomes [39,118,127]. Low severity burning may stimulate lateral bud growth similar to pruning and assist in eradication of parasites [118]. Burning that consumes large amounts of duff is most harmful to thinleaf huckleberry regeneration [106]. Quantity of heat released by fire and relative amounts of duff and soil moisture are controlling factors [105].
In western Montana, spring burning is recommended to increase thinleaf huckleberry density within the Douglas-fir/western larch habitat type, except when lower duff and soil are dry [106]. In moist Douglas-fir habitat types of Montana, where ponderosa pine and lodgepole pine are seral components, low severity burning in the early spring stimulates thinleaf huckleberry, increasing shoot density [153]. In the Lolo National Forest, low and moderate severity surface fires increase density and nutrient content of thinleaf huckleberry in moist Douglas-fir and cool, dry Douglas-fir habitat types [35]. In the Douglas-fir/thinleaf huckleberry habitat type, spring fires and moderate amounts of shade may enhance production of thinleaf huckleberry [18].
In the grand fir series of the eastern Cascade Range, 2 consecutive fires in short intervals favor thinleaf huckleberry over grand fir, and big huckleberry may share dominance with lodgepole pine after intense fires on moist sites [1]. Dense stands of thinleaf huckleberry may not burn if fuels are limited, due to low flammability of thinleaf huckleberry foliage [106]. Density of thinleaf huckleberry may be increased by low severity surface fires in subalpine fir/thinleaf huckleberry habitat type in northern Utah [100].
In sub-boreal spruce zones of British Columbia, postfire sprouting of big huckleberry occurs almost exclusively through rhizomes. Postfire recovery is slow in the 1st 10 years postfire [69]. Likewise, in mesic and drier sites of the sub-boreal spruce zone in Canada, thinleaf huckleberry recovers slowly after fire [68].
Thinleaf huckleberry has wide ecological amplitude [108], occupying moist, moderately deep, well-drained soils [64,120]. Thinleaf huckleberry is found on moderate slopes or benches, rocky hillsides, and avalanche chutes [65,98,122,148]. Thinleaf huckleberry is rarely found in valley bottoms [82]. As an understory species, thinleaf huckleberry can grow beneath a partially closed forest canopy, or in sunny openings [54,64]. Big huckleberry has greatest potential on cool mesic sites with minimal overstory [32].
Soils: Thinleaf huckleberry prefers soils with a pH around 5.5 [111]. Clay and silt content are usually low (under 40%) leaving soil with a fine, loamy texture [138]. Relatively low concentrations of essential elements are required to sustain growth. Mesic and drier sites are preferred, although thinleaf huckleberry may inhabit soils with a wide range of available moisture [64].
In Montana, Goldin and Nimlos [58] evaluated thinleaf huckleberry presence in the Garnet Mountains in relation to soil physical properties. Thinleaf huckleberry prefers quartzite and granitic soils to limestone-derived soils possessing similar pH and gravel content. Quartzite soils resulted in the greatest coverage of thinleaf huckleberry, compared to granite and limestone derived soils:
Relative Cover (%) Limestone1
Granite9
Quartzite16
Within sites, thinleaf huckleberry grew under Douglas-fir on limestone, limber pine on quartzite and subalpine fir on granite.
Aspect/Slope: Thinleaf huckleberry prefers northern aspects [92] although populations may exist on all aspects [99]. Martin [99] observed thinleaf huckleberry to prefer moderate to steep slopes (25-40%). Gentle slopes were found to allow greater competition from other plant species.
Elevation: Elevation by geographic area is :
California [74] 3,609 to 7,217 feet (1,100-2,200 m) Montana 3,000 to 9,650 feet (914-2,930 m) Oregon and Washington [138] 3,000 feet (914 m) to high mountains Utah [162] 8,202 to 10,318 feet (2,500-3,145 m)Big game: Thinleaf huckleberry is a good food source for grizzly bears and black bears [34,161] and is a key food item for bears in Montana [117]. Bears feed upon berries, leaves, stems [5], and roots [84]. Thinleaf huckleberry is the dominant huckleberry species consumed by grizzly and black bears of Glacier National Park, Montana [84] and a major shrub food item in Yellowstone National Park [88]. Bears may begin feeding upon thinleaf huckleberry berries in mid-July at lower elevations 3,000 to 3,937 feet (900-1,200 m) of Glacier National Park [161].
Thinleaf huckleberry is a minor component in the summer diet of western Montana elk [45]. Elk feed on thinleaf huckleberry when leaves are young and tender [165]. Thinleaf huckleberry also provides browse for moose in north-central Idaho [124].
Thinleaf huckleberry is an important species for white-tailed deer in grand fir and western redcedar forests of northern Idaho, with greatest use occurring in the fall [86].
Avian: Although not preferred, thinleaf huckleberry provides a fall food source for blue grouse in Oregon [31] and is an important food source for ruffed grouse [77].
Depending upon environmental constraints/conditions, thinleaf huckleberry
may occur as a dominant understory species with Engelmann spruce
(Picea engelmannii), western larch (Larix occidentalis),
limber pine (Pinus flexilis), ponderosa pine (P. ponderosa),
lodgepole pine (P. contorta) [9,123], western white pine (P. monticola),
western hemlock
(Tsuga heterophylla) [123], and mountain hemlock (T. mertensiana)
[51]. Pacific silver fir (Abies amabilis), subalpine fir (A. lasiocarpa), noble fir (A. procera),
white fir (A. concolor), grand fir (A. grandis), Douglas-fir (Pseudotsuga
menziesii),
and western redcedar (Thuja plicata) [163] and are also dominant overstory species [49,63].
Common shrub associates include sticky flowering currant (Ribes viscosissimum),
mountain snowberry (Symphoricarpos oreophilus) [9,24], common snowberry
(S. albus), grouse whortleberry (Vaccinium scoparium), Cascade bilberry (V. deliciosum),
red huckleberry
(V. parvifolium) [20], Utah honeysuckle
(Lonicera utahensis), bearberry (Arctostaphylos uva-ursi) [9],
fool's huckleberry (Menziesia ferruginea) [9,42]. Other common shrub
associates include white spirea
(Spirea betulifolia) [123,142], whiteveined wintergreen
(Pyrola picta) [20], pink mountainheath (Phyllodoce empetriformis),
Cascade azalea (Rhododendron albiflorum), Sitka mountain-ash
(Sorbus sitchensis), western moss-heather (Cassiope mertensiana), strawberryleaf raspberry
(Rubus pedatus), roughfruit berry (R. lasiococcus) [42], little
prince's pine (Chimaphila menziesii) [11], Rocky Mountain maple (Acer glabrum)
[46,89], Pacific dogwood (Cornus nuttallii) [120], and Oregon-grape
(Mahonia repens) [11].
Pacific Northwest:
Thinleaf huckleberry is well represented in subalpine habitats [14,53,112]. In mesic
subalpine communities, thinleaf huckleberry is a common understory associate of Pacific silver fir and mountain hemlock [51]. Thinleaf huckleberry is an important
understory component of subalpine fir forests in the eastern Olympic Mountains,
Washington [50]. Within the Cascades of Oregon and Washington,
thinleaf huckleberry frequently occurs on dry subalpine sites with beargrass [53,112].
Thinleaf huckleberry is a dominant species within fir/hemlock (Abies spp./Tsuga
spp.)
stands in the Cascade Mountains, understory to Pacific silver fir, noble fir,
mountain hemlock, Douglas-fir, western white pine, and western redcedar [163].
Within fir/hemlock (Tsuga spp.) understory communities in the Cascades of southern Washington,
thinleaf huckleberry is often codominant with common beargrass [53].
Thinleaf huckleberry is historically an important food item in the diet of many Pacific Northwest Native Americans [78,82,84,93,118].
Thinleaf huckleberry may hybridize with Vaccinium cultivars, producing drought-resistant cultivars for the West Coast [33].
Growth of thinleaf huckleberry is fixed. Leaf primordia are initiated prior to spring bud break. Seasonal growth involves shoot extension through internode elongation [59].
Throughout thinleaf huckleberry's range in Montana, flowering begins the 1st week of June with total floret development requiring 4 months (mid-July to October) [59]. Gough [59] observed vegetative and reproductive development in the Lee Metcalf Wilderness, Montana, at 6,562 feet (2,000 m) with an 80-day growing season. Shoot growth from vegetative buds on stems began in mid-May. Buds on plants where the soil was still frozen showed no bud break. Vegetative buds on shoots greater than 0.08 inches (2 mm) diameter swell before buds on thinner, less vigorous shoots. Shoot elongation occurs until mid- to late June. Seasonal shoot growth is generally completed within a 4-week period [59].
Drew [44] mapped the phenology of thinleaf huckleberry within the cedar/hemlock zone of Idaho. Onset of leaf fall was directly related to limitations in soil moisture availability. Bud burst occurred early to mid-April followed by leafing out (beginning of May) and stem elongation (May-beginning of July). Leaf fall is initiated in mid-August [44].Thinleaf huckleberry is adapted to sprout after fire and is efficient in storing nutrients released from burning [139]. Thinleaf huckleberry sprouts after fire from shallow and deep rhizomes [30,106] or root crown [1]. Heat penetration into soil layers where rhizomes occur will affect thinleaf huckleberry's ability to produce postfire, vegetative sprouts [106].
In preferred habitats, thinleaf huckleberry will generally survive low to moderately severe fires, attaining prefire coverage within 3 to 7 years [19,25], with stem number and density increasing. High severity burns may result in moderate to high mortality [39] or greatly reduced sprouting [71]. Moderate to severe fires on coarse textured soil or areas with a thin organic layer kill underground rhizomes, resulting in heavy mortality [25,130]. Strong decreases occur after severe broadcast burning and wildfire with recovery generally occurring within 15 to 20 years [9]. Overall, low severity burns result in heavy sprouting from rhizomes [39].
Thinleaf huckleberry may reproduce through seed or by vegetative production from adventitious buds on rhizomes [80,140] and root crown [1]. Reproduction through seed is rare under natural conditions. Populations are usually maintained through lateral expansion of vegetative clones [80,140].
Seed: Flowers are pollinated by bees [79,99] with each stem node having the capacity to produce 1 berry [32]. A typical berry carries 47 seeds. Mean germination is around 42% [138].
Fruit production is not halted during dry summers. Fructification may occur after 4 to 6 months void of rain [33]. In the southern Washington, Cascade Mountain region, individual stems are capable of producing fruit for 14 years [32]. Although berry production is moderately tolerant of moisture deficits, successful germination and subsequent establishment is extremely reduced or eliminated by water stress. Cool spring temperatures also negatively affect seed germination [140].
Establishment through seed is not heavily relied upon after disturbance. Number of seedlings emerging from soil blocks collected from a western hemlock/Pacific rhododendron (Rhododendron macrophyllum)/dwarf Oregon-grape community was monitored after experimentally applied disturbance. Thinleaf huckleberry showed no regeneration from seed after burning and mechanical mixing of soil layers [80].
Thinleaf huckleberry offers a relatively minor contribution to soil seed banks. Viable seed most often occurs within the 1st 2 inches (5cm) of soil. Kramer and Johnson [89] evaluated the soil seed banks of Douglas-fir/ninebark habitat type; grand-fir/Rocky Mountain maple habitat type; and grand-fir/big huckleberry habitat types in central Idaho. The constancy (%) of viable, buried, thinleaf huckleberry seed, by habitat type is summarized below:
Douglas-fir/ninebark Grand fir/Rocky Mountain maple Grand fir/thinleaf huckleberry 6 31 25Vegetative: Thinleaf huckleberry possesses an extensive system of rhizomes [64,106], with adventitious buds distributed evenly along the length of the rhizome [106]. Vegetative production is relied upon highly for regeneration after disturbance [80]. Fruit productivity is more sensitive to solar radiation than vegetative production [32].
Thinleaf huckleberry may occur in early or late seral stages [32,69,99]. It generally shows greatest productivity within sites that experienced disturbance about 50 years previously [99]. Hamilton and Yearsley [69] describe thinleaf huckleberry as a "fairly shade-tolerant" species.
Fields dominated by thinleaf huckleberry are seral.
Decline of thinleaf huckleberry as forests move toward climax status is inevitable, especially in areas of crown closure [32]. Without disturbance, thinleaf huckleberry will gradually decrease in dominance, crowded out by trees [108].
Early seral: In spruce-fir forests thinleaf huckleberry may have a significant presence within 1 to 5 postdisturbance years [22]. Response varies greatly with intensity of disturbance. In a spruce-fir forest in Idaho, thinleaf huckleberry was not a dominant shrub until 40-79 years after clear cutting, sharing understory dominance with wild ginger (Asarum caudatum) in sites undisturbed for 80 years or longer [133].
Habeck [62] observed thinleaf huckleberry as a common understory component of pioneer and seral communities within cedar-hemlock habitats of Glacier National Park, Montana. Thinleaf huckleberry is also an early seral species in western redcedar-western hemlock forests of northern Idaho [150].
In grand fir habitats of north-central Idaho, thinleaf huckleberry may occupy an important role in early seral stages at high elevations on north slopes [167]. Thinleaf huckleberry decreases as a major understory species of developing grand fir/Douglas-fir stands above 3,937 feet (1,200 m) in the Selway-Bitterroot Wilderness of Montana and Idaho as stands move toward maturity [63]. Thinleaf huckleberry is well represented throughout all seral stages in grand fir/thinleaf huckleberry habitat types. Steele [142] presents a detailed model of succession in the grand-fir/thinleaf huckleberry habitat type.
In subalpine prairies of the Mount Hood area, Oregon, thinleaf huckleberry is an early seral plant species [118]. Thinleaf huckleberry is greater in frequency and coverage in open stands of mountain hemlock and Pacific silver fir associations and decreases as stands close [42].
Late seral: Thinleaf huckleberry is a widespread understory dominant in late seral and climax communities in subalpine forests [4]. Within Montana, northern Idaho, and eastern Washington habitat types, thinleaf huckleberry generally shows a slow recovery increasing toward a peak at 20 to 30 postdisturbance years [92].
The Wind River Nursery [70] in Carson, Washington, provides suggestions for successful thinleaf huckleberry propagation. Initial planting is recommended in flats with subsequent transplanting of germinants to individual pots. Flats should be covered with glass or plexiglass to reduce soil moisture loss and placed in a cool location (large refrigerator or unheated greenhouse) to provide cool moist stratification. After stratification, flats should be transferred directly to heated greenhouse for germination. Seedlings should be hand transplanted to pots.
Flowering by new seedlings usually requires 3 growing seasons [113].
