Stickney [299] found Rocky Mountain maple to be sensitive to fire, with low
survival, slow redevelopment, and slow recovery of percent cover on sites in
Montana burned by wildfire and on broadcast burned sites.
For further information on postfire responses of multiple species in plant communities with Rocky Mountain maple, see the following Fire Studies:
In early to mid stages of growth, Rocky Mountain maple provides hiding cover for big game animals as well as small mammals and birds [81,142,195,325]. It also provides nesting sites for sharp-shinned hawks in Utah [258].
Cover value of Rocky Mountain maple has been rated as follows [85]:
UT CO WY MT Elk fair -- poor fair Mule deer good fair fair -- White-tailed deer -- -- poor fair Antelope poor -- poor -- Upland game birds fair -- poor fair Waterfowl poor -- poor -- Non-game birds good good fair fair Small mammals good good fair fairRocky Mountain maple is a native, deciduous tall shrub or small tree [56,66,74,123,141,159,169,172,203,256,310,325,328,333]. It often grows 20 to 30 feet ( 6.1-9.1 m) tall, with crown widths from 10 to 20 feet (3-6 m) wide and a stem diameter up to 12 inches (30.5 cm) [74,123,150,156,172,175,203,234,243,310,325,328], though it can reach 40 feet (12.2 m) tall [169,259] and 2 feet (0.6 m) in diameter [169]. Rocky Mountain maple is usually tall and spindly in closed stands, with a more dense and brushy growth form in open stands [233,234]. Though it may have a single dominant stem [80], Rocky Mountain maple most often occurs as a multi-stemmed shrub 5 to 6.5 feet (1.5-2 m) tall [74,80,123,169,172,325].
Rocky Mountain maple has opposite, ascending to erect branches, rounded twigs, and a narrow crown [123,150,325]. The bark of Rocky mountain maple is smooth until maturity, when fissures develop [150,156,159,310,325]. Rocky mountain maple has a wide, spreading root system with a combination of deep and lateral woody roots [123,310,325].
Rocky Mountain maple may be monoecious [74,123,150,172,203,256,310] or dioecious [74,123,141,172,203,310,325,328]. Flowers are borne in loose terminal cymes arising from lateral buds [74] and grow in drooping clusters [123]. The paired seeds are winged samaras [74,123,141,150,325,328]. Seeds are 0.16 to 0.2 inch (4-5 mm) long [256] and samaras are 0.08 to 0.12 inch (20-30 mm) long [203].
Rocky Mountain maple has been characterized as fire dependent, and may decline with fire exclusion [22]. Prolific sprouting and wind dispersal of seed of Rocky Mountain maple facilitate rapid revegetation of burned areas [56,144,176,259,284]. In quaking aspen/Rocky Mountain maple communities in Colorado, this rapid regeneration results in postfire vegetation that quickly resembles the prefire community [259]. Following fire, enhanced growth of Rocky Mountain maple may result in moderate growth loss of conifers and mortality of shade-intolerant conifers [86]. Due to aggressive competition, it may also interfere with conifer seedling establishment [280].
Rocky Mountain maple occurs as a major component or dominant in seral shrubfields in the northern Rockies. These shrubfields result from canopy removal by repeated severe fires [55,58,63,105,113,135,139,179,196,227,288,329,337]. Seral shrubfields have also been maintained with prescribed fire [184]. A lack of seed combined with increased soil temperatures and moisture stress inhibit tree regeneration and maintain the shrubfields. Fuels in persistent shrubfields consist primarily of the shrubs themselves with little large downed woody material and low litter amounts; in one study conducted in northern Idaho, fuel loading averaged 19.7 tons/acre. Persistent shrubfields may burn in any season; if fuels are continuous and dry, spring fires spread readily, and in summer, hot and dry conditions are exacerbated by nighttime inversions [288].
FIRE REGIMES:
Fire return intervals for plant communities and ecosystems in which Rocky Mountain maple occurs are summarized below. 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".
Rocky Mountain maple was a principal component of slowly recovering open sites in western Montana after stand-replacing fire and broadcast burning [299]. It is highly competitive with tree species after burning [86,281]. Fire results in a substantial increase in Rocky Mountain maple sprouts [295].
Prescribed fire may initially reduce the percent cover of Rocky Mountain maple substantially, though in several years it is expected to approach or surpass pretreatment coverage [285]. Percent cover of Rocky Mountain maple may increase dramatically over prefire levels within 5 years of burning, however, variable results may be expected [62].
Rocky Mountain maple may experience an increase in crown volume following disturbance, sprouting more after burning than after logging treatments [56]. Within 3 years, crown diameters of Rocky Mountain maple may be equal to or greater than diameter prior to burning [180]. However, other studies have found that 2 years after burning, Rocky Mountain maple only recovered 8% of its prefire crown volume, and proportion of total shrub volume had decreased from 80% prefire to 14% postfire [193]. Three out of 4 harvest and burning treatments in Montana were found to effectively reduce Rocky Mountain maple shrub volume, though it began increasing again after 2 years posttreatment. The 4th treatment (no burning) left more individuals intact and they subsequently demonstrated less sprouting and Rocky mountain maple experienced no dramatic decline or increase in shrub volume [274]. After prescribed burning in Idaho, Rocky Mountain maple averaged 120 sprouts per plant; fall burning produced fewer but longer sprouts than spring burning [182]. Mean heights for Rocky Mountain maple were found to be greater on logged/broadcast burned sites than on logged or logged/piled/burned sites in Idaho [233].
Prescribed burning is used to maintain seral shrubfields and provide winter range for elk by retarding conifer dominance, decreasing the height of browse plants, increasing browse quality and palatability, and stimulating forage plants to regenerate from seed [179,180,212,240,288]. However, Rocky Mountain maple quickly grows out of reach of browsing animals due to its rapid regrowth after fire [139,180,326]. Miller and others [212] found that low-temperature fires might encourage excessive growth with leaders exceeding 6.5 feet (2 m) in a single growing season. Severe burns that actually damage Rocky Mountain maple and stunt leader growth may be better utilized to reduce leader heights to a usable level of 1.6 feet (.5 m) or less. Prescribed fire effectively improves forage availability in the short-term [25,56,193,195,326,331], and has been found to reduce height of Rocky Mountain maple from 7 to 16 feet (2.1-4.9 m) before fire to less than 7 feet (2.1 m) after fire [198]. Asherin [25] found that by the end of the 3rd postfire growing season, Rocky Mountain maple height exceeded 8 feet (2.4 m). Four years after burning in Idaho shrubfields, 80% of twig production remained within reach of elk [181,182]. Repeated burns at 10 to 15 year intervals are expected to maintain Rocky Mountain maple availability [181,182,184,288]; however, it is often difficult to re-establish trees on these sites in the future [288]. Broadcast burning of clearcuts in the northern Rockies may produce these seral shrubfields [162,281,338]; in 1 study, shrub-dominant vegetation occurred by the 8th postfire year [338]. Rocky Mountain maple was present within 4 years on another lightly burned clearcut [126].
After burning, browse production may be higher than prefire production initially [56,183], but annual production was observed to taper off by the 10th year, falling below prefire browse production [183]. Both spring and fall burning appear to increase Rocky Mountain maple palatability, based on heavy use in burned areas and browsing of larger twigs [180]. Crude protein levels may be higher in Rocky Mountain maple for up to 4 years following fire [240].
Injury due to fire may increase Rocky Mountain maple susceptibility to infection by parasitic Cytospora species [78].Temperature:
Rocky Mountain maple occurs in subalpine boreal, boreal, temperate, semiarid, and mesothermal climates [164,167]. Approximate temperatures on Rocky Mountain maple sites range from 14 to 75 degrees Fahrenheit (-10-24 oC) [188,257,265,313]. Annual precipitation may by as low as 9 inches (229 mm) and as high as 60 inches (1,542 mm) [100,127,177,188,257,313,316].
Location:
Rocky Mountain maple occurs on wetlands, streambanks, canyons, and upland mountain slopes [2,71,72,74,158,172,239,263,265,307,325]. Though it occurs on both moist and dry sites [4,21,30,31,61,74,123,151,190,203,310,312], Rocky Mountain maple is more closely tied to drainages in arid zones of its distribution [79,97,177,310,311,324,325], but occurs on drier exposures northward and at higher elevations [325]. On upland sites, Rocky Mountain maple grows on lower, mid, and upper slopes [82,177,228,236,271], alluvial terraces [123,259], summits, ridgetops [4,177], snow chutes [122,123,204], and talus slopes [166,174,204,208]. Rocky Mountain maple is found on gentle, moderate, and steep slopes [82,177,188,189,205,228,233,290,336], with slopes ranging from 15 to 67% [3,99].
Elevation:
In southern California, Rocky Mountain maple is found from 5,980 to 10,000 feet (1,823-3,048 m) [222,316]. In Arizona and New Mexico, it is found between 5,000 and 12,000 feet (1,524-3,658 m) [7,47,79,82,153,203,221,228,261,307,324] on all aspects [4,81,177,192,228,311,324]. The lower elevation sites are often along streams or drainages [47,48,81,99,177,221,228]. In Colorado and Utah, Rocky Mountain maple grows at 5,000 to 12,700 feet (1,524-3,871 m) [40,93,130,159,174,175,205,242,290,310,336], with northern aspects being optimal for growth and establishment [310].
In northern California, northwestern Nevada, and Oregon, Rocky Mountain maple is common between 2,800 and 9,000 feet (853-2,743 m) [64,175,244]. In Idaho, Montana, and Washington, Rocky Mountain maple occurs between 1,500 and 8,900 feet (457-2,712 m) [36,56,70,75,91,112,196,257,269,293,295,335] on all aspects [61,100,196,234,249]. On sites in Idaho, percent cover of Rocky Mountain maple increased with elevation, but frequency did not [339]. Though it occurs on all aspects, studies in northern Idaho found that Rocky Mountain maple had significantly greater (F=0.05) percent cover on southern aspects than on northern aspects [233]. In British Columbia, Rocky Mountain maple occurs from 1,148 to 4,760 feet (350-1,450 m) [188,189].
Soils:
Rocky Mountain maple occurs on silty, loamy, sandy, gravelly, and rocky soils [45,100,127,177,205,228,290,325,336], with a moderately acidic to slightly basic pH [290,310,325]. It grows on sandstone, limestone, basalt, gneiss, rhyolite, calcareous, and granitic parent materials [45,64,100,112,127,205,290,316]. Rocky Mountain maple grows on shallow [123,233] as well as relatively deep [100,150,228,233,236,310], well developed soils [3,4,156]. Rocky Mountain maple has high requirements of calcium, magnesium, nitrogen, potassium, and phosphorus [123,167,233]. In British Columbia, it is reported to be an indicator of nitrogen-rich soils [164].
Drought and Shade Tolerance:
Rocky Mountain maple occupies well-watered [164] and well-drained sites [45,100,123,177,228,310,325], though it will tolerate imperfectly drained soils, periodic flooding, and moderately high water tables [90,166,167,325]. Rocky Mountain maple occupies sites with a range of moisture levels, competing by adjusting total leaf area through stomatal control and shifting the water potential of its leaves [123]. Rocky Mountain maple has a weak to moderate drought tolerance [310,325] and is winter hardy [123,167,169,325]. It is also moderately shade tolerant [123,226,310,325], but experiences more vigorous growth and fruiting in full sun [325].
Rocky Mountain maple is generally an important browse species for domestic livestock [150] and wildlife throughout its range [22,33,56,57,123,139,145,206,212,269,335]. In British Columbia, importance is low for caribou, moderate to high for elk and mule deer; high for mountain goats; and moderate for white-tailed deer, bighorn sheep [41], and moose [41,68]. Rocky Mountain maple is valuable for mule deer [163,223], moose [110,172], and elk [172,185,223] in the northern Rockies and Pacific Northwest, and it is preferred browse for big game animals in Wyoming [38]. Rocky Mountain maple is a potentially valuable forage species for deer and elk in Arizona [314]. Big game animals generally consume the buds and current annual twig growth [179]. However, Rocky Mountain maple often grows quickly out of reach [56,212].
Rocky Mountain maple is a principal forage species of shrubfields in the northern Rockies, which provide important winter range for deer and elk [21,70,102,179,180,196,288,326,334].
Though it is also browsed in the summer [157,286], Rocky Mountain may be heavily used in late fall and winter by mule deer and white-tailed deer [84,123,157,171,207,237,238]. It is also important winter browse for bighorn sheep [123,317], and elk [105,123,204,320,334]. Rocky Mountain maple is particularly important winter and spring moose browse [123,254,257,298].
Ruffed grouse in Idaho and blue grouse in Nevada eat the leaves and buds of Rocky Mountain maple [202]. Rocky Mountain maple seeds are also important forage for grosbeaks [172] and small mammals [172,287].
Rocky Mountain maple commonly occurs as an understory species in a variety of
coniferous forest types, as well as in upland deciduous and riparian forests
throughout its range. Rocky Mountain maple also occurs in a variety of mixed
shrub vegetation [241,319].
Common Plant Associates:
Rocky Mountain maple is found with a variety of tree species throughout its
range, including
white fir (Abies concolor)
[27,28,32,73,81,82,104,177,192,227,228,236,261,278,330,336],
subalpine fir (Abies lasiocarpa)
[43,73,91,177,228,236,261,282,288,307,330,336],
alder (Alnus spp.) [32,75,95,166,191,298,330],
birch (Betula spp.) [239,265],
common juniper (Juniperus communis) [8,73,95,205],
Rocky Mountain juniper (Juniperus scopulorum) [271],
western juniper (Juniperus occidentalis) [223], Engelmann
spruce (Picea engelmannii) [81,91,177,236,261,278,282,288,307,330],
lodgepole pine (Pinus contorta) [16,34,37,71,91,169,200,282],
limber pine (Pinus flexilis) [71,209],
ponderosa pine (Pinus ponderosa) [16,71,113,143,153,187,200,231,330],
cottonwood (Populus spp.) [32,166,191],
quaking aspen (Populus tremuloides) [31,32,35,71,166,168,259,261,307,325,336], Douglas-fir (Pseudotsuga menziesii)
[71,91,121,177,194,227,228,252,261,278,282,288,319,325,329,330],
oak (Quercus spp.) [40,261,336],
and willow (Salix spp.) [15,32,81,95,166,177,194,210,236,298,307,319].
Several shrub species are commonly found with Rocky Mountain maple throughout
its range, including
bigtooth maple (Acer grandidentatum) [40,205,228,330],
Saskatoon serviceberry (Amelanchier alnifolia) [16,35,49,71,81,82,91,95,166,177,194,210,228,233,284,319,325,336],
bearberry (Arctostaphylos uva-ursi) [70,82], red-osier dogwood (Cornus sericea) [48,90,210,298],
oceanspray (Holodiscus discolor) [49,236,261,278,319],
Utah honeysuckle (Lonicera utahensis) [91,236,257,336],
Oregon-grape (Mahonia repens) [8,70,71,81,82,177,319],
Oregon boxwood (Paxistima myrsinites) [71,81,82,177,264,284,333],
ninebark (Physocarpus malvaceus) [49,71,233,236,319,336],
chokecherry (Prunus virginiana) [16,35,71,166,269,319,325,336], Gambel oak (Quercus gambelii)
[3,40,95,168,307],
currant/gooseberry (Ribes spp.) [8,29,194,278,284],
rose (Rosa spp.) [70,71,107,166,257,284],
thimbleberry (Rubus parviflorus) [82,91,135,236,264,284], red elderberry (Sambucus racemosa) [16,166,210,233,236], russet buffaloberry (Shepherdia canadensis) [91,134,209,336],
common snowberry (Symphoricarpos albus) [49,92,134,233,257,269,319], and mountain snowberry (Symphoricarpos
oreophilus) [8,70,81,82,177,236,271].
Associated species (northern):
Rocky Mountain maple occurs commonly with several species in the northern
portion of its distribution (Alaska south to northern California, Nevada, and
Utah). Associated tree species include
Pacific silver fir (Abies amabilis) [27,34,101,161],
grand fir (Abies grandis) [96,121,143,148,149,252,260,264,306,333],
California red fir (Abies magnifica) [14,26,27,244],
vine maple (Acer circinatum) [164,210],
bigleaf maple (Acer macrophyllum) [69],
Sitka alder (Alnus viridis ssp. sinuata) [70,210,257],
Pacific madrone (Arbutus menziesia) [69,210],
paper birch (Betula papyrifera) [91,200],
Port-Orford cedar (Chamaecyparis lawsoniana) [297,313],
California hazel (Corylus cornuta var. californica) [210],
Douglas hawthorn (Crataegus douglasii) [16,210],
western larch (Larix occidentalis) [91,111,143,148,200,249,276,282,329],
white spruce (Picea glauca) [90,200],
Sitka spruce (Picea sitchensis) [34], western white pine (Pinus monticola)
[91,140,143,148,264],
Oregon white oak (Quercus garryana) [297,313],
Sadler oak (Quercus sadleriana) [28],
Pacific willow (Salix lasiandra) [210],
Pacific yew (Taxus brevifolia) [2,151,226,284],
western redcedar (Thuja plicata) [10,27,34,119,121,143,160,187,200,288],
western hemlock (Tsuga heterophylla) [10,27,34,91,101,119,124,148,161,264,333], and mountain hemlock (Tsuga mertensiana)
[27,161].
Common shrub associates in the northern part of Rocky
Mountain maple's range include
Pacific serviceberry (Amelanchier florida) [223],
sagebrush (Artemisia spp.) [223,269,328],
redstem ceanothus (Ceanothus sanguineus) [105,135,319],
snowbrush ceanothus (Ceanothus velutinus) [23,105,138,196,223,269],
birchleaf mountain-mahogany (Cercocarpus betuloides) [297,313], curlleaf mountain-mahogany (C. ledifolius)
[35,200,223],
rock clematis (Clematis columbiana) [70,319],
Pacific dogwood (Cornus nuttallii) [210], salal (Gaultheria shallon)
[69],
orange honeysuckle (Lonicera ciliosa) [319],
menziesia (Menziesia ferruginea) [8,226,257],
Pacific bayberry (Myrica californica) [210],
devil's club (Oplopanax horridus) [8,284],
Lewis' mockorange (Philadelphus lewisii) [64,319],
bittercherry (Prunus emarginata) [16,134,135,210,223,319],
bitterbrush (Purshia tridentata) [223,269],
cascara (Rhamnus purshiana) [233,319],
bristly black currant (Ribes lacustre) [284],
baldhip rose (Rosa gymnocarpa) [91,284,319],
red raspberry (Rubus idaeus) [64,90,251],
blue elderberry (Sambucus cerulea) [16,210,233,319],
Greene mountain-ash (Sorbus scopulina) [16,75,90,205,233,284],
Sitka mountain-ash (S. sitchensis) [70,90,194],
white spirea (Spiraea betulifolia) [8,59,64,91,257],
tree spirea (Spiraea discolor) [69],
California laurel (Umbellularia californica) [297,313],
and big huckleberry (Vaccinium membranaceum) [91,151,257,264,284].
Other common plant associates include queencup beadlily (Clintonia uniflora)
[8,9], fireweed (Epilobium angustifolium) [8,9,100],
oak fern (Gymnocarpium dryopteris) [2],
sword fern (Polystichum munitum) [2],
twinflower (Linnaea borealis) [8,70,151,284],
Cascades azalea (Rhododendron albiflorum) [8], smooth woodrush (Luzula hitchcockii)
[8],
pinegrass (Calamagrostis rubescens) [23,100],
and elk sedge (Carex geyeri) [100].
Associated species (southern):
Rocky Mountain maple occurs commonly with several species in the southern
portion of its distribution. Common tree species include
boxelder (Acer negundo) [97,191,325],
New Mexico locust (Robinia neomexicana) [81,168,177,261],
blue spruce (Picea pungens) [32,95,177,227,261],
Rocky Mountain bristlecone pine (Pinus aristata) [227], and southwestern white pine (Pinus strobiformis) [153,227,278].
Common shrub associates occurring with Rocky Mountain
maple in the southern part of its range include
silvertip sedge (Carex foena) [236],
true mountain-mahogany (Cercocarpus montanus) [242],
cliffbush (Jamesia americana) [81,82,177,236],
bush oceanspray (Holodiscus dumosa) [63,81,177,242],
Arizona honeysuckle (Lonicera arizonica) [81,177],
Texas mulberry (Morus microphylla) [191], mountain ninebark (Physocarpus monogynus)
[81,82,177], black cherry (Prunus serotina) [97,191],
smooth sumac (Rhus glabra) [242], and blueberry elder (Sambucus glauca)
[48].
Plant Communities:
Classifications describing plant communities in which
Rocky Mountain maple is a dominant species are as follows:
Arizona [7,81,99,228,236,309]
California [28]
Colorado [6,32,71,82,165,259]
Idaho [70,290,291,292,294,295,296]
New Mexico [3,4,7,81,82,99,177,228,309]
Oregon [28,64,152]
Utah [205,336]
Washington [332]
Wyoming [5,71,290]
Rocky Mountain maple is generally favored by fire, recovering and increasing by sprouting vigorously from the root crown [44,71,132,178,182,185,193,224,229,264,288,303,325]. Sprouting of Rocky Mountain maple was observed 1 year after a severe fire in northern Montana [154]. After a severe crown fire in Idaho, Rocky Mountain maple sprouted within the first growing season [293]. The greatest sprouting response, however, is observed following light severity fires, with the least response occurring after a high severity burn [86]. Following a broadcast burn in Idaho, Rocky Mountain maple regenerated its entire prefire crown volume in the first postfire year [339]. Following fire, Rocky Mountain maple may grow 4 to 5 feet (1.2-1.5 m) in 3 years [86]. Rocky Mountain maple usually increases following fire, though survival and response may be reduced by severe fire [43,44,288,300].
Rocky Mountain maple also colonizes sites after fire via wind-dispersed seed [288].
Seed production:
The mating system of Rocky Mountain maple is dioecious or staminate plants with some bisexual flowers [136]. Rocky Mountain maple likely begins to produce seed before 10 years of age [243]. The large seeds [128] are dispersed by wind [123,176,256,284,294,295], and Rocky Mountain maple often seeds into disturbed areas [62]. Seeds are both animal and wind pollinated [256]. Existing literature is conflicting regarding on-site seed storage; Stathers and others [289] report that Rocky Mountain maple regenerates from seed stored on-site, while Steele and Geier-Hayes [291,294,295] state that seed is not stored. Large seed crops occur every 1 to 3 years [123,243]. Seeds remain viable for short periods of time, losing their viability during dry, frosty periods [123]. Rocky Mountain maple seeds germinate in partial shade on mineral soil [86,123,294,295] or shallow organic layers [123]. Due to embryo dormancy, Rocky Mountain maple seeds require approximately 6 months of chilling to germinate [279].
Vegetative regeneration:
Following stem damage or top-kill, Rocky Mountain maple readily sprouts from the root crown [33,62,72,123,176,186,193,295]. Sprouts may not set seed for 3 years after disturbance [72].
Development:
Rocky Mountain maple experiences a rapid increase in height following disturbance, which tapers off around 20 years post-disturbance. Growth modeling estimates that Rocky Mountain maple may reach 4.2 feet (1.3 m) 2 years after disturbance and 10 feet (3 m) by 10 years after disturbance [178], and may overtop even rapidly growing tree seedlings [215]. Maximum heights are reached approximately 30 to 40 years after disturbance [233], on sites with 40 to 50% of full sunlight [144]. Even in closed canopies, Rocky Mountain maple grows above the dominant shrub layer [56].
Rocky Mountain maple occurs in old-growth and second-growth forests [13,148,187,209,257]. It is found in early seral stages [12,15,23,30,71,72,109,126,145,176,193,199,201,208,257,266,294,318,338,339], growing within the first 10 years following fire [303] through mature and climax stages [12,15,23,56,67,72,108,115,120,128,148,201,225,226,257,266,294,302,333,338,339]. In British Columbia, Rocky Mountain maple is common in deciduous pioneer forest communities [69] and in late successional and climax floodplain vegetation [60]. On sites in northern Idaho, Rocky Mountain maple was present in unlogged stands as well as stands 7, 14, and 25 years following logging. However, the presence of Rocky Mountain maple was found to decrease in later successional stages [333]. Also in northern Idaho, Rocky Mountain maple was found in closed, non-disturbed stands as well as stands subjected to various harvest and burn treatments [233]. As a prolific sprouter, Rocky Mountain maple rapidly revegetates disturbed areas [56]. Rocky Mountain maple is one of the most common deciduous species occurring on mesic sites in avalanche paths due to its ability to survive avalanche impact pressures via sprouting, and is characteristic of avalanche paths in northern Montana [52,53].
Rocky Mountain maple is a major component or dominant in seral shrub-dominant vegetation, which develops rapidly following disturbance in the northern Rockies [36,55,57,58,70,105,113,114,125,133,184,245,299,329,338]. Seral shrubfields result from recurring disturbance including fire and downslope movement of snow, ice, water, and rocks [55,184]. These shrubfields may actually inhibit tree seedling establishment through direct competition and indirectly by providing habitat for browsing animals that damage seedlings [125]. The Rocky Mountain maple/mallow ninebark complex frequently becomes dominant on sites in the northern Rockies [65]. Similar seral shrubfields occur in the southern Rockies. Rocky Mountain maple may actually provide shade to Douglas-fir seedlings aiding in establishment and survival [63].
Rocky Mountain maple may have higher percent cover or occur with greater frequency on more open sites [145,173]. However, Antos [15] found that Rocky Mountain maple shows little response to successional development, maintaining >5% cover in both young and old stands. Rocky Mountain maple is described as shade intolerant to shade tolerant [128,164]; the ability to persist in heavy shade makes it an important species in closed canopy stands [234].
The currently accepted scientific name of Rocky Mountain
maple is Acer glabrum Torr. (Aceraceae)
[74,87,137,141,155,156,172,327,328]. Recognized infrataxa are as follows:
Acer glabrum var. diffusum (Greene) Smiley [136,155,328], Rocky Mountain maple
Acer glabrum var. douglasii (Hook.) Dippel [137,155], Douglas maple
Acer glabrum var. glabrum Torr. [137,155,203,328], Rocky Mountain maple
Acer glabrum var. greenei Keller [136,155], Greene's maple
Acer glabrum var. neomexicanum (Greene) Kearney & Peebles
[155,203,328], New Mexico maple
Acer glabrum var. torreyi (Greene) Smiley [136,155], Torrey maple
Rocky Mountain maple is used for revegetating cutslopes and roadsides following highway construction [77], and is recommended for riparian revegetation projects in the western United States [54].
Rocky Mountain maple seed is commercially available [76] and should be stored dry at 35 to 41 degrees Fahrenheit (1.7-5 oC) [322]. Though storage for less than 2 years is recommended [129,322], Rocky Mountain maple seeds may be viable up to 3 years [123,279]. Germination requirements include 180 days of warm stratification [322,325] at 68 to 86 degrees Fahrenheit (20-30 oC) [243] and 180 days of cold stratification [129,243,279,322,325] at 37 to 41 degrees Fahrenheit (2.8-5 oC) [243]. In a laboratory test, 40% of seeds kept at 50 to 60 degrees Fahrenheit (10-15.6 oC) both night and day germinated within 30 days [243]. Shade is recommended for seedling establishment [322]. Rocky Mountain maple can also be transplanted; though better results are achieved with older plants than with seedlings [325], bareroot seedlings are often used for restoration and rehabilitation projects [129].
Acer glabrum is a species of maple native to western North America, from southeastern Alaska, British Columbia and western Alberta, east to western Nebraska, and south through Washington, Oregon, Idaho, Montana and Colorado to California, Arizona, Utah, and New Mexico.[2]
Acer glabrum is a small tree growing to 6–9 metres (20–30 feet) tall, exceptionally 12 m (39 ft), with a trunk around 13 centimetres (5 inches) in diameter, exceptionally around 25 cm (10 in).[3] The leaves are 2–13 cm (3⁄4–5 in) broad, three-lobed (rarely five-lobed),[3] variable in the depth of lobing, occasionally so deeply lobed as to be divided into three leaflets; the lobes have an acute apex and a coarsely serrated margin. The flowers are produced in corymbs of five to ten, yellowish-green, at the same time as the new leaves in spring. The fruit is a samara or winged seed, which develops in fused pairs at an angle of less than 45° when mature, though some varieties spread out to 90°.[3][4][5]
There are four to six varieties, some of them treated by some authors at the higher rank of subspecies:[2][5][6]
Acer glabrum is plentiful in many parts of the Rocky Mountains, Cascade Mountains, Olympic Mountains and the Sierra Nevada, often growing with ponderosa pine, Douglas-fir, and quaking aspen.[7] It can be found in dry rocky areas.[3]
It tends to be found in brush fields arising from fire-disturbed sites. Conifers tend to replace it in well-forested areas.[3] The foliage is browsed by game animals (especially deer and elk in winter), cattle, and sheep.[3][8]
Native Americans utilized the strong stems for snowshoe frames, bows, and other applications.[3] Some Plateau Indian tribes drink an infusion of Douglas maple as a treatment for diarrhea.[9] Ramah Navajo use an infusion of the glabrum variety for swellings, and also as a "life medicine", or panacea.[10][11]
Acer glabrum is a species of maple native to western North America, from southeastern Alaska, British Columbia and western Alberta, east to western Nebraska, and south through Washington, Oregon, Idaho, Montana and Colorado to California, Arizona, Utah, and New Mexico.
