Some indicate that dry, windy fire conditions are necessary to kill curlleaf mountain-mahogany trees [11,126]. Likely the requirement of dry, windy conditions depends on stand characteristics and available fuels.
Two of forty curlleaf mountain-mahogany plants on sites burned in the Moose Creek Fire in the Salmon National Forest of Idaho had green growth in the 1st postfire year. One plant was burned on the trunk and was brown from heat. The other did not burn but was brown from heat. In the 1st postfire year, 1 surviving plant had new leaves on approximately 33% of its branches, and the other had a single branch with new leaves and many sprouts [37]. No information on the subsequent growth or survival of these plants was provided.
Because curlleaf mountain-mahogany is commonly killed by fire, the rate of
curlleaf mountain-mahogany recolonization of the site is highly
dependent on seed bank survival or distance to the nearest seed source, both of which
may vary with fire severity. Seed-producing plants may have survived low-severity
burning or may escape fire in low fuel, fireproof refugia.
Early postfire effects:
Seed bank survival is typical on only low-severity or moderate-severity burned sites.
Curlleaf mountain-mahogany was killed on both severely and moderately burned
sites in northeastern Oregon. Severe fires consumed litter and duff, and white ash was
common. All tree stems were consumed, and trunks were deeply charred on severely
burned sites. Moderate fires scorched trees' small stems and leaves and charred trunks.
Litter and woody debris were only partially consumed on moderately burned sites. On the severely burned site, no
curlleaf mountain-mahogany seedlings were found by the 5th postfire year. On the moderately burned site,
curlleaf mountain-mahogany seedlings were present in both the 1st and 5th postfire years, and average
cover of curlleaf mountain-mahogany in both years was 1%. Findings suggest that the
curlleaf mountain-mahogany seed bank survived the moderate fire but not the severe fire [98].
On the Balls Ranch in the western part of the Great Basin, curlleaf
mountain-mahogany stands with old trees were killed, although the fire burned
sites with very low fuel levels. Fire behavior was not described, and burned and
unburned stands were not compared [166].
The Moose Creek Fire on the Salmon National Forest burned in drought conditions.
Temperatures were high, humidity levels were low, and winds were gusty.
Fire behavior was "variable." Curlleaf mountain-mahogany suffered high
mortality. Of 40 individuals examined in the 1st postfire year, only 2 survived.
Plants that survived the fire or escaped the fire in unburned patches produced
"huge quantities" of seed in the 1st postfire growing season. No
information beyond the 1st postfire year was reported [37]. A severe
fire that burned in August in the Frank Church River of No Return Wilderness,
Idaho, completely killed many curlleaf mountain-mahogany stands, and no sprouts or seedlings were observed
for the 1st three postfire growing seasons. Other fire characteristics or fire
weather conditions were not reported, but researchers described the fire as "hot"
[155,199].
Later postfire effects:
Several studies indicate that curlleaf mountain-mahogany regeneration on burned sites rarely takes more than
30 years and in some cases can be quick. In Mountain City, Nevada, over
4,000 three-year-old seedlings/acre occurred on burned sites visited in postfire year
7, following a stand-replacing fire that burned on 21 October. Researchers believed
seedlings germinated from the soil seed bank. Two percent of the
curlleaf mountain-mahogany trees sprouted following the fire in Mountain City.
Between 1% and 4% of the curlleaf mountain-mahogany trees sprouted following a fire in Targhee,
Idaho, and postfire sprouts were observed only from plants 20 to 30 years of age.
In Challis, Idaho, curlleaf mountain-mahogany regeneration took approximately 30 years following a
severe summer fire that "apparently destroyed" any seed source. Poor seedling
establishment on burned sites may have been a product of limited seed dispersal and/or harsh site
conditions [71].
Researchers visited a curlleaf mountain-mahogany stand near Mackay, Idaho, that burned
approximately 71 years earlier. Curlleaf mountain-mahogany plants ranged from 8 to 54 years old,
suggesting that regeneration began 17 years following the fire.
In another stand that burned in 1965, researchers found no curlleaf
mountain-mahogany regeneration in 1968 [173]. No information on fire season
or severity was provided.
In the singleleaf pinyon-California juniper-western juniper vegetation type
of the San Bernardino Mountains of California, researchers sampled a chronosequence
of burned areas where postfire date ranged from 5 to 160 years. Curlleaf
mountain-mahogany was "established sparingly" on areas burned over 47 years earlier and
"persisted" on sites burned 78 or more years ago. Fires were likely severe
and stand-replacing, with high tree and shrub mortality. See Fire Ecology
for more information on the fire regime for this area and vegetation type [223].
Fuels/fire behavior:
The following study provides
information on fuel conditions and fire behavior in curlleaf mountain-mahogany-big sagebrush
vegetation type during different moisture conditions. In Lava Beds National
Monument, a wildfire burned on 11 July, when the daytime high temperatures were approximately
82 °F (28 °C), relative humidity levels were 20%, wind speeds were
9.3 to 12 miles per hour (15-20 km/hour), and dead wood between 0.2 to 1 inch (0.5-2.6 cm) in diameter averaged 3% moisture.
There was no precipitation in the month previous to the wildfire. Under these conditions, just 5% of the
study area was unburned, and curlleaf mountain-mahogany cover was 0% in the burned study area. A
prescribed fire burned in early July when the daytime high temperatures averaged
81 °F (27 °C), relative humidity levels were 18%, winds were
0 to 7.5 miles per hour (0-12 km/hour), and dead wood between 0.2 to 1 inch (0.5-2.6 cm) in diameter averaged 6%
moisture. This fire followed a month with exceptionally high precipitation levels. In the
prescribed fire area, 37% of the area remained unburned, and curlleaf mountain-mahogany cover was 19.3% within the
perimeter. Whether or not the curlleaf mountain-mahogany survived in burned areas or just
in unburned patches within the prescribed fire area was not reported [208].
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g. [25,68,80,83,86,105,113,226,228]).
Aboveground description: Curlleaf mountain-mahogany is a multi-branched evergreen tree or shrub. Mature plants range from 3 to 35 feet (0.9-11 m) tall [25,38,41,68,85,113,114,143,228]. One to several trunks is common. Main trunks may be more than 3 feet (0.9 m) in diameter but average 12 inches (30 cm) [79,95,105,114,171]. Young plants typically have branches growing near the ground, producing a shrubby appearance. Plants may not reach full height until 100 or more years of age [95,157]. Curlleaf mountain-mahogany is drought tolerant and grows slowly [112,114]. Plants are long lived. The oldest trees located in the Shoshone Range of Nevada were an estimated 1,350 years old [45,176]. Nineteen curlleaf mountain-mahogany-dominated communities scattered throughout Utah had high levels of morphological variability. There were treelike and shrublike plants with an average of 1.75 and 5.6 stems/plant, respectively. Canopy height ranged from an average low of 7 feet (2 m) on 1 plot to a high average of 15 feet (4.6 m) on another. Average tree age was 85, but 1 tree was estimated at 723 years of age [42].
Bark on curlleaf mountain-mahogany trees is thick and measures up to 1 inch (2.5 cm) [95,114]. As bark ages, furrows develop [38]. Furrows on old trunks can be an inch wide [214]. Curlleaf mountain-mahogany leaves are simple, entire, and alternate. The thick, resinous, leathery leaves are linear to oblong and pointed at both ends. A thick cuticle, sunken stomata, and revolute margins aid in reducing water loss and increase curlleaf mountain-mahogany's success in drought conditions. Leaves are often clustered at the stem tips [41,68,80,83,85,86,105,113,171,198,226]. Leaves measure 0.4 to 1.7 inches (1-4.2 cm) long by 0.1 to 0.4 inch (0.3-1 cm) wide [38,68,79,83,143,228]. Leaves are typically shed after 2 or 3 years [25,26]. A study of plants in central Utah found that curlleaf mountain-mahogany leaves are "primarily functional" for an average of 18.5 months [165].
Curlleaf mountain-mahogany flowers are perfect [85,198] and apetalous. Calyx tubes from 0.1 to 0.4 inch (3-10 mm) long are produced at the leaf axils of stem tips on 2nd-year wood [53,80,86]. Flowers occur singly or in clusters of up to 5, although clusters of 2 or 3 are most common [38,52,68,79,143,228]. Curlleaf mountain-mahogany produces achenes with a long, persistent, plumose style or tail. They are hard and narrow, with sharp tips. Seeds measure 0.2 to 0.4 inch (4-10 mm) long, and tails are often 1 to 3 inches (2.5-8 cm) long [19,79,83,85,86,105,143,198,228].
The wide range in plant, leaf, and fruit sizes and form is reduced slightly with the recognition of curlleaf mountain-mahogany varieties; however, the lack of agreement among systematists in the recognition of varieties confounds any discussion of differing traits. For more information on distinguishing varieties see [52,83,86,105,113,125,201].
Underground description: The curlleaf mountain-mahogany root system is shallow and spreads widely [202]. On the "best soil sites" in Oregon and adjacent areas, curlleaf mountain-mahogany roots with at least 0.2 inch (5 mm) diameter reached to 3.9 feet (1.2 m) deep [45]. Curlleaf mountain-mahogany plants can support nitrogen-fixing bacteria in root nodules [34,101,109,232]. Nodulated plants grown in a greenhouse were more "vigorous," produced darker green foliage, and had "somewhat" higher foliar nitrogen concentrations than plants without nodules [237]. In the San Bernardino Mountains of California, soil taken from limber pine-curlleaf mountain-mahogany communities had more total nitrogen than soils where limber pine grew without curlleaf mountain-mahogany. Researchers calculated that nodulated plants could add 6.9 kg/ha of total nitrogen in a 200-day growing season in areas with a continuous curlleaf mountain-mahogany canopy [118].
Curlleaf mountain-mahogany is the most widely distributed of the mountain-mahoganies (Cercocarpus spp.) [43]. It occurs from southeastern Washington south to southern California and Baja California, and east to south-central Montana and western Colorado [51,52,86,103]. The southernmost population of curlleaf mountain-mahogany is in Sierra San Pedro Martir of Baja California [137]. Curlleaf mountain-mahogany is widespread in Nevada, Utah, and Idaho [103,173,228]. Populations of curlleaf mountain-mahogany in Arizona are only known from the Grand Canyon [120].
The U.S. Geological Survey provides a map of curlleaf mountain-mahogany's distribution. For a map that includes the distribution of C. l. var. ledifolius and C. l. var. intercedens, see [216]. For additional descriptions of the distribution of all curlleaf mountain-mahogany varieties, see [52,86,113,226].
Fire adaptations: Curlleaf mountain-mahogany has thick bark and may survive "light" fires [71,127]. Sprouts following fire are rare and short lived [11,145]. Most often curlleaf mountain-mahogany is killed by fire, and regeneration is by seedling establishment [71]. Seed may come from curlleaf mountain-mahogany trees avoiding fire in low fuel areas [45] or by seed surviving in soil [98].
FIRE REGIMES: Some curlleaf mountain-mahogany stands occupy sites with very low fuel levels that rarely burn. However, many researchers indicate that curlleaf mountain-mahogany abundance has increased in the absence of fire since the early 1900s.
Fuels: Fuel characteristics can vary considerably in curlleaf mountain-mahogany communities. In the Lamoille Canyon of the Ruby-East Humboldt Mountains, curlleaf mountain-mahogany communities on north-facing slopes supported an understory of shrubs, forbs, and grasses that produced 1,000 pounds of vegetation/acre. On south-facing slopes soils were shallow, conditions were drier, and understory production was 100 pounds/acre [119]. In curlleaf mountain-mahogany stands in southwestern Montana, bare ground and rock averaged 50% cover, and summer grass coverage was 7% [53]. In limber pine-Douglas-fir forest types in central Idaho, the fire interval is "relatively long." A lack of continuous fuels, sparse undergrowth, open stand structure, and low downed wood accumulations do not support frequent fire [39]. On the Wallowa-Whitman National Forest, curlleaf mountain-mahogany communities also occupy sites that do not carry fire well [97]. Very large trees in the western juniper/curlleaf mountain-mahogany habitat type in Lava Beds National Monument of California had fire scars, suggesting that stand-replacing fires were rare. Erhard [57] indicated that bare pumice and cinder soils may have restricted fire spread. In these habitats, rock coverage was 44%, and litter coverage was 36% [57].
Several studies report that the oldest curlleaf mountain-mahogany trees occupy harsh sites with very low fuel levels. Researchers observed the oldest trees in curlleaf mountain-mahogany-dominated communities throughout Utah in rocky areas that were likely protected from fire [166]. Studies of curlleaf mountain-mahogany stands in Oregon and adjacent areas revealed that old trees (>300 years) occupied rocky sites while younger trees were found on less harsh sites with deeper soils. The researcher suggested that 400- to 600-year old relict curlleaf mountain-mahogany sites were missed by past fires because the rocky sites did not burn [45].
Fire exclusion and curlleaf mountain-mahogany range expansion: Fire exclusion in curlleaf mountain-mahogany habitats has facilitated increased curlleaf mountain-mahogany abundance and successful regeneration in some areas. Repeat photography revealed that curlleaf mountain-mahogany increased in the absence of fire in warm, dry sites in southwestern, central, and southeastern Montana [72] and in parts of Utah's Fishlake National Forest. Early photographs from Utah showing low curlleaf mountain-mahogany coverage date from 1905 to 1938, and recent photographs with increased coverage date from 1996 to 2001 [104].
A thick understory of curlleaf mountain-mahogany and antelope bitterbrush (Purshia tridentata) developed in ponderosa pine woodlands of Lava Beds National Monument after fire was excluded [94]. In presettlement times, fires were probably very common in wooded areas of Lava Beds National Monument. Modoc and Shasta natives utilized fires for hunting, and lightning is common from late spring through summer [127]. Frequent fires likely restricted curlleaf mountain-mahogany to the "roughest and most barren" areas. Ponderosa pine reproduction has suffered in the thick understory, and increased fuel loads have likely altered fire behavior from presettlement time [94].
From fire scars, fire history, historical literature, and past photos, researchers suggest that fire "restricted curlleaf mountain-mahogany development" in curlleaf mountain-mahogany stands in Montana, Idaho, Wyoming, Utah, and Nevada. Since European settlement fire size and frequency have decreased, and curlleaf mountain-mahogany regeneration has "far exceeded former levels." In the earliest photos of the study areas, curlleaf mountain-mahogany was confined to rocky sites or thin soil sites where fires were likely infrequent. Stand age analysis indicates that curlleaf mountain-mahogany abundance has increased in the past 170 years. Curlleaf mountain-mahogany stands on deep soils in central and southeastern Idaho and southwestern Montana were historically grasslands, and all curlleaf mountain-mahogany plants established after 1900. Researchers speculate that prior to 1900, a high fire frequency prevented curlleaf mountain-mahogany establishment [71].
In the Big Springs Wash and Decathon Canyon sites in Great Basin National Park, researchers reconstructed the fire history from singleleaf pinyon fire scars. Curlleaf mountain mahogany grew on the sites. Fires likely occurred somewhere in the area every 40 years between 1688 and 1896. Some very rocky sites with low fuel levels may have burned at 50- to 100-year intervals. Fires were commonly patchy producing a mosaic of burned and unburned areas. Curlleaf mountain-mahogany abundance increased tremendously with the exclusion of fire after 1900 [74].
FIRE REGIMES and changes: Fire frequency and size changes since European settlement of the Intermountain West are extremely common, but some curlleaf mountain-mahogany habitats remained unchanged since European settlement and management.
A mean fire return interval of between 13 and 22 years from 1750 to the early 1900s was estimated from fire-scarred ponderosa pine trees scattered in curlleaf mountain-mahogany stands on steep south- and west-facing slopes of the Salmon River Canyon in Idaho. Since 1900 the fire return interval has increased substantially due to heavy livestock grazing, which reduced the amount of fine fuels, fire exclusion practices, and/or decreased human-caused fires. While curlleaf mountain-mahogany was likely restricted to rocky sites where fuel levels were low prior to 1900, curlleaf mountain-mahogany did regenerate when fires were frequent. At the time of the study, curlleaf mountain-mahogany stands were decadent, and researchers hypothesized that fire may have been important to curlleaf mountain-mahogany recruitment or "vigor" [7].
In the Petersen Mountains of western Nevada, the area occupied by curlleaf mountain-mahogany has "decreased dramatically" from 1954 to 1997 as a result of increased fire incidence. Increased fire frequency has been linked to increased cheatgrass dominance. The area occupied by curlleaf mountain-mahogany in 1954 was nearly 14% more than that occupied in 1996. The researcher predicts that the current fire frequency in the areas will make successful recruitment impossible [166].
Singleleaf pinyon-California juniper (Juniperus californica)-western juniper woodlands of California's San Bernardino Mountains support a fire regime that has not changed with fire exclusion practices. The open fuel arrangement in these woodlands support a long fire-return interval of severe stand-replacing fires that kill most shrubs and trees. Fires require extreme weather conditions [223]. In western and central Nevada, researchers evaluated the age structure in curlleaf mountain-mahogany stands on 3 mountain ranges. Stands were multiaged, contained some very old trees (1,350 years old), and had several fire-scarred curlleaf mountain-mahogany trees. A sparse understory and natural fire breaks on the sites suggested that fires were rare. When fires occurred, severity was probably low and mature, thick-barked curlleaf mountain-mahogany trees likely survived [176].
The following table provides fire return intervals for plant communities and ecosystems where curlleaf mountain-mahogany is important. Find 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) California chaparral Adenostoma and/or Arctostaphylos spp. <35 to <100 sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [154] basin big sagebrush Artemisia tridentata var. tridentata 12-43 [172] mountain big sagebrush Artemisia tridentata var. vaseyana 15-40 [5,32,134] Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (x=40) [218,233] California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [154] curlleaf mountain-mahogany* Cercocarpus ledifolius 13-100+ [7,74,176] mountain-mahogany-Gambel oak scrub Cercocarpus ledifolius-Quercus gambelii <35 to <100 western juniper Juniperus occidentalis 20-70 Rocky Mountain juniper Juniperus scopulorum <35 pinyon-juniper Pinus-Juniperus spp. <35 [154] Rocky Mountain bristlecone pine P. aristata 9-55 [49,50] whitebark pine* Pinus albicaulis 50-200 [1,3] Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [16,17,204] Sierra lodgepole pine* Pinus contorta var. murrayana 35-200 [4] Colorado pinyon Pinus edulis 10-400+ [61,69,106,154] Jeffrey pine Pinus jeffreyi 5-30 Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [4] interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [4,12,116] quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [4,70,133] Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [4,5,6] coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [4,140,164] oak-juniper woodland (Southwest) Quercus-Juniperus spp. <35 to <200 [154] *fire return interval varies widely; trends in variation are noted in the species reviewMany researchers suggest that fire in decadent or seral stands may increase curlleaf mountain-mahogany regeneration. Gruell and others [71] suggest that continual protection of curlleaf mountain-mahogany from disturbances will decrease productivity. Fire is recommended for old-aged stands. Stands with low fuel levels and some curlleaf mountain-mahogany trees confined to rocky sites would likely retain a seed source and are the best candidates for prescribed fire. Fire may also be useful in increasing curlleaf mountain-mahogany productivity in seral stands where conifers are "competitive" and curlleaf mountain-mahogany is not reproducing. Fires in the fall will likely leave some curlleaf mountain-mahogany survivors in areas where woody fuels are sparse [71].
In areas where Douglas-fir saplings and pole-sized trees are successionally replacing curlleaf mountain-mahogany plants in west-central and southwestern Montana, prescription fires may encourage curlleaf mountain-mahogany regeneration and increase herbaceous vegetation production. Prescribed fire in these stands would also decrease fuel loads and reduce the chance of severe fire [73].
Fire should be discouraged in big sagebrush-antelope bitterbrush mule deer winter range on the east side of the Sierra Nevada range. Fire incidence has increased in recent time. From 1957 to 1982, 49,000 acres (20,000 ha) of winter range burned, but from 1983 to 1988, 159,000 acres (64,300 ha) burned. On burned sites, cheatgrass is typically the most abundant species. The stomach contents of mule deer taken in December of 1951 and 1952 revealed diets of mostly browse: big sagebrush, antelope bitterbrush, and curlleaf mountain-mahogany. Dry cheatgrass was 6% of mule deer diets at that time. Mule deer analyzed in 1987 had diets composed primarily of dry cheatgrass (79%) [217].
Prescription fire guidelines/fuel moisture contents: Prescription fire guidelines to encourage curlleaf mountain-mahogany persistence and regeneration have been developed for several areas and vegetation types. Martin and Johnson [127] provide parameters for burning in bitterbrush and curlleaf mountain-mahogany communities in Lava Beds National Monument. Guidelines vary slightly with amount of dead woody fuel. In curlleaf mountain-mahogany stands with Douglas-fir saplings and pole-sized trees in west-central and southwestern Montana, prescription fire guidelines are provided to encourage curlleaf mountain-mahogany regeneration. Fires in the spring or fall, which are described in detail in [73], will likely kill 50% to75% of the Douglas-fir and mountain big sagebrush, eliminate litter, expose mineral soil, and produce a mosaic of burned and unburned patches.
Curlleaf mountain-mahogany foliar moisture content prediction models were developed in Lava Beds National Monument based on a drought index and moisture contents monitored for 3 years, spring through fall. Foliar moisture content generally decreased from spring through fall, and the average minimum moisture content was 44.3% [149].
Fire scars for fire history information: While curlleaf mountain-mahogany trees do produce fire scars, curlleaf mountain-mahogany scars are inferior to most juniper or ponderosa pine trees available in nearby stands for fire history reconstruction. Curlleaf mountain-mahogany scars can be caused by ungulates, rodents, insects, and/or fire. Recent scars (younger than 50 years) can be attributed to fire by the presence of charcoal; however, older fire scars can be linked to fire only by finding more than 3 well-developed scars in a stand that dated to approximately the same year. Dating scars on curlleaf mountain-mahogany is difficult because obscured annual growth is common [7].
Curlleaf mountain-mahogany grows in scattered patches and in extensive pure stands on dry, rocky, steep slopes in the Intermountain West between lower conifer and desert steppe communities [25,38,41,80,114,143,198]. Sagebrush, pinyon-juniper (Pinus-Juniperus spp.), mountain brush, quaking aspen (Populus tremuloides), and fir-spruce (Abies-Picea spp.) vegetation types are typical curlleaf mountain-mahogany habitat [56,83,228].
Climate: Curlleaf mountain-mahogany occupies habitats with low precipitation and extreme temperature ranges. Several researchers report that curlleaf mountain-mahogany requires just 10 to 24 inches (250-610 mm) of annual precipitation per year for good growth [26,153,159]. Stevens and Monsen [196] report that the average annual precipitation in curlleaf mountain-mahogany habitats ranges from 15 to 26 inches (380-660 mm).
Idaho/Utah: In curlleaf mountain-mahogany habitats in the mountain ranges of south-central Idaho and northwestern Utah, summers are hot and dry with temperatures ranging from 32 to 95 °F (0-35 °C), and winters are cold and windy with temperatures between -15 to 23 °F (-26 to -5 ° C). Humidity levels rarely exceed 40%, and precipitation is unreliable but averages 12 inches (300 mm) [2]. In the Douglas-fir/curlleaf mountain-mahogany habitat in the Wasatch Range near the Utah/Idaho border and in the Stansbury Mountains in northern Utah, wind is typical all year, insolation is "intense," and snow pack is low and short lived [128].
Nevada: The average annual precipitation in curlleaf mountain-mahogany habitats of western and central Nevada is 14 to 45 inches (360-1,150 mm), most of which comes in the winter as rain or snow in the Carson Range. Average annual precipitation is less, 16 to 20 inches (410-510 mm), and comes between March and June in the Shoshone Range. The mean number of frost-free days ranges from 30 to 80 days [176]. In northeastern Nevada's Lamoille Canyon, the summer minimum and maximum temperatures recorded from 30 June to 26 August in a curlleaf mountain-mahogany stand at 7,200 feet (2,200 m) elevation were 95 °F (35 °C) and 54 °F (12 °C), respectively [123].
Oregon: Dealy [45] provides specific information on the soil, elevation, and climate for habitat types dominated by curlleaf mountain-mahogany in Oregon and adjacent areas. In the curlleaf mountain-mahogany/Idaho fescue-bluebunch wheatgrass habitat type of northern Lake County, annual precipitation averages 12 inches (300 mm). Winter snow provides 66% of the precipitation, and just 5% comes in the summer months [44].
Elevation: Curlleaf mountain-mahogany habitats range from 2,000 to 9,800 feet (600-3,000 m) elevation in the Intermountain West [30]. In general the range is 2,000 to 4,600 feet (600-1,400 m) in the northern part of curlleaf mountain-mahogany's range and to 9,000 feet (2,700 m) in the southern part of its range [43,214]. Occupied elevations are highest in Utah, Nevada, and east-central California [42].
Region/state Elevation (m) Arizona known only in Grand Canyon at ~2,000 [120] 1,800-2,900 m [105] California 1,200-3,000 [83,144,171] northwestern and west-central Colorado 2,000-2,700 [79] west-central Montana reaches 2,200 [113] Nevada 1,200-2,700 [103] found at over 3,050 m [176] Utah 1,400-3,000 [56,95,153,228] Great Basin 1,500-3,000 [114]Soils: Curlleaf mountain-mahogany occupies sites with shallow to deep, well-drained, nutrient-poor, sandy loam soils with weak development [26,41,45,83,103]. While a wide range of textures are tolerated, curlleaf mountain-mahogany is most common on dry, coarse-textured substrates [198]. In California's San Bernardino National Forest, curlleaf mountain-mahogany is indicative of carbonate substrates [67].
Nineteen curlleaf mountain-mahogany stands located throughout Utah were most commonly located on sandy loam soils, but loams and clay loams were also encountered. Soils were shallow; penetrometer depths averaged 6.5 inches (16.5 cm). Soil pH ranged from 5.9 to 7.8, and soluble salt levels were low [40,42]. The treelike and shrublike growth forms were thought to be related to soluble salt levels and sand percentages in the soils [40]. In the Greater Yellowstone Ecosystem, curlleaf mountain-mahogany was most common on limestone soils [124]. Soils in curlleaf mountain-mahogany habitats of western and central Nevada were well-drained, gravelly, sandy loams with low water-holding capacities and an effective rooting depth of 6 to 40 inches (20-100 cm) [176]. In central Idaho, soils of the Douglas-fir/curlleaf mountain-mahogany habitat type varied widely. Parent materials included limestone, shale, sandstone, pumice, and quartzite, and pH ranged from 5.5 to 7.9 [190]. Based on several studies in the Intermountain West, soil conditions in curlleaf mountain-mahogany habitats had an average depth of 6.3 inches (16 cm), pH of 6.9, soluble salt levels of 284 ppm, and clay, silt, and sand percentages of 16.2, 25.5, and 58.3, respectively [30].
Curlleaf mountain-mahogany provides food and cover for a variety of wildlife species. It is most often praised as big game forage [114]. Some livestock (domestic goats, sheep, and cattle) use it in spring, fall, and/or winter but rarely in the summer [171,214]. Big game browsing can be extensive; consumption of all the leaves and stems within reach is common [171]. Garrison [65] suggests that utilization of 50% to 60% for curlleaf mountain-mahogany plants under 60 inches (150 cm) tall is tolerated. As plants mature, stems are often beyond the reach of big game animals [157].
Cattle: In the Wallowa-Whitman National Forest, cattle utilization of curlleaf mountain-mahogany is low because of the steep slopes occupied [97]. Utilization of summer range in south-central Utah was evaluated in September. In areas without cattle, utilization of curlleaf mountain-mahogany was 10.8%; in a grazing allotment area, utilization was 21.4%. The differences, however, cannot be solely attributed to cattle, as mule deer pellet counts in the allotment were 1.7 times greater on sites with cattle than without cattle [100].
Deer: Curlleaf mountain-mahogany is highly palatable to deer and provides important cover. Based on pellet counts, researchers considered curlleaf mountain-mahogany habitats "well used," especially in the winter in the mountain ranges of Cassia County, Idaho, and Box Elder County, Utah. Curlleaf mountain-mahogany communities were believed to be lowrisk feeding habitats, as just 5% of mountain lion kills were in curlleaf mountain-mahogany habitats. Perceived predation risks, assessed through the density of food given up, were lower in curlleaf mountain-mahogany than Douglas-fir habitats [2]. Douglas-fir/curlleaf mountain-mahogany and limber pine/curlleaf mountain-mahogany vegetation types in northern Utah are valuable deer habitat [128]. Curlleaf mountain-mahogany/Idaho fescue-bluebunch wheatgrass and curlleaf mountain-mahogany/Idaho fescue vegetation types in northern Lake County, Oregon, are valuable to mule deer in the fall, winter, and spring, providing both food and cover. Larger curlleaf mountain-mahogany plants are often browsed to deer reach, and small plants are kept hedged [44].
Curlleaf mountain-mahogany provides excellent summer and winter forage for mule deer in Wyoming [150], and mule deer browsing in Montana produces a "twisted and gnarled" plant shape [113]. Mule deer pellet density was significantly (p<0.05) greater on unburned curlleaf mountain-mahogany sites in eastern Nevada's Quinn Canyon Range than on 4-year-old burned sites. Shrub coverage was greater on unburned than burned plots, although not significantly [185]. Estimates of mule deer utilization in 22 curlleaf mountain-mahogany stands in southwestern Montana ranged from 0% to 90%. Generally stands with heavy winter usage produced more growth the following growing season than those without heavy use. In a stand with no winter utilization, curlleaf mountain-mahogany produced a mean of 43,254 twigs/ha the following spring. In another stand with 89% winter utilization, 759,257 twigs/ha were produced the next spring [53]. Kufeld and others [111] summarized mule deer diet information from approximately 98 studies in the western U.S. Curlleaf mountain-mahogany most often received moderate mule deer use. Use was heavy in the summer and fall based on 3 studies [111].
In the Devil's Garden winter range area of the Modoc National Forest, curlleaf mountain-mahogany made up just 0.3% of the vegetation in the study area. Based on mule deer stomach contents, the highest levels of curlleaf mountain-mahogany use were in February (11.8% by volume and 50% in frequency). In the Truckee Canyon winter range near the California-Nevada border, curlleaf mountain-mahogany made up 1.2% of the available vegetation, and the highest levels of curlleaf mountain-mahogany came from stomachs analyzed in December. Curlleaf mountain-mahogany content was 7.0 % by volume and 80% in frequency [117]. Captive mule deer feeding trials revealed that curlleaf mountain-mahogany and curlleaf mountain-mahogany à true mountain-mahogany are preferred winter food sources [181,184]. In summer feeding trials curlleaf mountain-mahogany was not preferred [183].
Deer/Elk: Elk consumed more curlleaf mountain-mahogany than mule deer in a Utah study. Feces collected from January through March revealed that the relative density of curlleaf mountain-mahogany in elk diets was 3% and in mule deer diets was less than 1% [141]. Curlleaf mountain-mahogany and Utah juniper-curlleaf mountain-mahogany stands in the Big Horn Mountains of Wyoming are important wintering habitat for elk and deer. Curlleaf mountain-mahogany plants in this area are hedged from heavy browsing [48].
Elk: Curlleaf mountain-mahogany and Utah-curlleaf mountain-mahogany stands in the Big Horn Mountains of Wyoming are important elk calving areas [48].
Moose: Aerial surveys and ground transects were used to assess the use of winter habitats by mule deer, elk, and moose in southwestern Wyoming. Mule deer and elk were observed in curlleaf mountain-mahogany habitats, but only moose were observed significantly (p<0.01) more than expected given the availability of the curlleaf mountain-mahogany vegetation. Snow depth, topography, and exposure likely affected use [148].
Pronghorn: On western Utah's Desert Experimental Range, pronghorn only lightly browsed curlleaf mountain-mahogany in the winter. It is important to note, however, that curlleaf mountain-mahogany was not a major component of the study area's vegetation [18].
Bighorn sheep: In Idaho's River of No Return Wilderness Area, 9% of the summer (June-August) diets of bighorn sheep herds in the Big Creek area were curlleaf mountain-mahogany (personal communication in [55]). Bighorn sheep were also observed in the curlleaf mountain-mahogany/bluebunch wheatgrass vegetation type in the Salmon River Breaks of central Idaho [115].
Mountain lions: The Douglas-fir/curlleaf mountain-mahogany habitat type of central Idaho provides important breeding and hunting grounds for mountain lions [190]. In the Big Horn Mountains of north-central Wyoming, researchers using radiotelemetry and tracking found that mountain lions preferred curlleaf mountain-mahogany habitat. Curlleaf mountain-mahogany vegetation was an important site for caching kills. Of 52 mountain lion caches, 32.7% were in curlleaf mountain-mahogany vegetation [121]. However, just 5% of mountain lion kills were in curlleaf mountain-mahogany stands in Cassia County, Idaho [2].
Small mammals: A variety of small mammals consume curlleaf mountain-mahogany seeds [157]. Researchers used deer mice captured from big sagebrush-antelope bitterbrush, singleleaf pinyon-Utah juniper, and Jeffrey pine-snowbrush ceanothus (Ceanothus velutinus) communities in western Nevada in captive feeding trials. Curlleaf mountain-mahogany seed consumption ranked 4th, 6th, and 8th out of 18 plant species for deer mice taken from Jeffrey pine, singleleaf pinyon, and big sagebrush habitats, respectively. Curlleaf mountain-mahogany preference increased by 4 times when presented to deer mice with less preferred foods [58]. Curlleaf mountain-mahogany leaves and fruits were common in woodrat middens in Lava Beds National Monument [132].
In California's Plumas National Forest, curlleaf mountain-mahogany pests and seeds were important foods for yellow-pine chipmunks. In the Jeffrey pine-curlleaf mountain-mahogany vegetation type, an ethmia caterpillar that feeds on curlleaf mountain-mahogany was the chief food for yellow-pine chipmunks, and approximately 50% of the seeds consumed by yellow-pine chipmunks were curlleaf mountain-mahogany [205].
Birds: The Douglas-fir/curlleaf mountain-mahogany habitat type of central Idaho provides important nesting sites for dusky grouse, dusky flycatchers, rock wrens, and American kestrels [190]. Chipping sparrows, dusky flycatchers, bushtits, Townsend's solitaires, and rufous-sided towhees were associated with curlleaf mountain-mahogany-big sagebrush communities in the Strawberry Creek drainage of Great Basin National Park [131]. In northwestern Nevada's Sheldon Wildlife Refuge, 61 passerine bird species were recorded along 4 transects visited from 1978 to 1984. Most common were gray flycatchers, scrub jays, Brewer's blackbirds, vesper sparrows, Brewer's sparrows, green-tailed towhees, sage thrashers, bushtits, blue-gray gnatcatchers, and American robins. Scrub jays and American robins used curlleaf mountain-mahogany for nesting, and gray flycatchers consumed insects while perched on curlleaf mountain-mahogany branches [64].
In the Bald Mountain range near the California-Nevada border, the red-breasted sapsucker has caused extensive damage and mortality in curlleaf mountain-mahogany stands. Of 5,509 investigated trees, 329 had severe red-breasted sapsucker damage. Damaged trees were not infested with insects and damage was typically a strip of drilling (12 inches (<30 cm) wide) at 4.9 to 6.6 feet (1.5-2 m) above the ground. The researcher suggested that red-breasted sapsucker damage may be a result of the recent large fires in the area that may have attracted the birds to nearby dead or dying conifers [166].
In the Caribou National Forest of southeastern Idaho, ruffed and dusky grouse were found in curlleaf mountain-mahogany-dominated habitats. Ruffed grouse used curlleaf mountain-mahogany vegetation a little in the summer, while dusky grouse used this vegetation type in the spring, summer, and fall. Fall dusky grouse use was significantly (p<0.05) more than expected [187]. Twenty-one percent of all dusky grouse hooting calls, but no brood observations, were in curlleaf mountain-mahogany vegetation types [188]. Dusky grouse droppings collected in the Schell and Toiyabe ranges of Nevada were 20% and 16% curlleaf mountain-mahogany by composition, respectively. Ten dropping samples were collected from each site [240].
Insects: Several insects feed on curlleaf mountain-mahogany. The mountain-mahogany looper feeds on curlleaf mountain-mahogany, but outbreaks in Utah are only known from areas where both curlleaf mountain-mahogany and antelope bitterbrush are present in large, dense, pure stands [63]. In northwestern Nevada, geometrid moth larvae defoliated approximately 10,000 acres (4,000 ha) of curlleaf mountain-mahogany plants in northwestern Nevada [209]. Tree mortality due to defoliation decreased with an increased number of Formica ant mounds on the site. For additional information on identifying the curlleaf mountain mahogany stands most susceptible to defoliation, see [64]. Some infestations of tent caterpillars and spiny silkworms were observed in curlleaf mountain-mahogany stands in southern and central Idaho [173].
Palatability/nutritional value: Curlleaf mountain-mahogany is "highly preferred" by big game, principally deer and elk [97]. In Utah, Parker [153] indicated that curlleaf mountain-mahogany had the "greatest palatability of any browse plant on mule deer range." In most areas, however, curlleaf mountain-mahogany palatability is rated good or excellent for deer and elk but fair to worthless for cattle, domestic sheep, and domestic goats [142,171,198].
Numerous studies report the nutritional content of curlleaf mountain-mahogany. Throughout California, curlleaf mountain-mahogany protein content ranged from a low of 6.2% (based on oven-dried weights) in February to a high of 12.3% in August [21]. In southwestern Montana, crude protein levels of current-year growth were 10.5% in the spring, 10.4% in the summer, 9.5% in the fall, and 9.8% in the winter [53]. Welch [227] reported that the digestible crude protein reported by Smith [182] exceed the protein requirements of mule deer in the winter season. Roper [165] provides the nutrient levels in curlleaf mountain-mahogany twigs and leaves for 3 locations in central Utah from April through September. Comparisons with true mountain-mahogany are provided as well [165]. Nutritional make up and digestibility of curlleaf mountain-mahogany in Utah are presented below [182].
Nutrient, content (%) Digestibility (%) protein, 10.6 54.3 ether extract, 9.1 42.9 crude fiber, 18 35.9 nitrogen-free extract, 58.2 76.3Curlleaf mountain-mahogany composition is presented below for plants collected in east Afton, Wyoming [78]. Collection time was not reported.
ash crude protein ether extract crude fiber nitrogen-free extract 5% 13.2% 10.3% 19.6% 51.9%Cover value: Big game species utilize curlleaf mountain-mahogany habitats for cover. Curlleaf mountain-mahogany communities in Oregon's Wallowa-Whitman National Forest provide excellent winter cover for big game [97]. In Wyoming curlleaf mountain-mahogany stands provide excellent hiding or escape cover and good thermal and fawning cover for mule deer [150]. In northwestern Nevada's Sheldon National Wildlife Refuge, curlleaf mountain-mahogany provides protection from the hot sun and cover for fawning deer [64]. For more information on the importance of curlleaf mountain-mahogany in wildlife habitats, see the species group of interest within Importance to Livestock and Wildlife.
Curlleaf mountain-mahogany is a dominant species in the following vegetation classifications:
General and/or Great Basin:
curlleaf mountain-mahogany/Idaho fescue (Festuca idahoensis) and curlleaf
mountain-mahogany/Idaho fescue-bluebunch wheatgrass
(Pseudoroegneria spicata) in areas where ponderosa pine (Pinus
ponderosa) forests meet big sagebrush (Artemisia tridentata)
communities in high desert steppe regions [45]
mountain-mahogany-oak (Quercus spp.) scrub in the southern Rocky Mountains and Great Basin [229]
singleleaf pinyon-curlleaf mountain-mahogany/slender buckwheat (Eriogonum microthecum)
at Great Basin-Mohave Desert ecotone
singleleaf pinyon-curlleaf mountain-mahogany/mutton grass (Poa fendleriana)
in southeastern Great Basin
singleleaf pinyon-curlleaf mountain-mahogany/Sandberg bluegrass (Poa secunda)
in southeastern Great Basin
singleleaf pinyon-curlleaf mountain-mahogany/Indian ricegrass (Achnatherum hymenoides)
in southeastern Great Basin
singleleaf pinyon-curlleaf mountain-mahogany/foxtail wheatgrass (Pseudelymus à saxicola)
in southeastern Great Basin [230]
curlleaf mountain-mahogany-littleleaf oceanspray (Holodiscus microphyllus) on 300- to 500-year-old lava
flows in Lava Beds National Monument [57]
curlleaf mountain-mahogany communities in San Bernardino Mountains [136]
curlleaf mountain-mahogany/arrowleaf balsamroot in south Warner Mountains of Modoc County [163]
Jeffrey pine (Pinus jeffreyi)-curlleaf mountain-mahogany and
Jeffrey pine-curlleaf mountain-mahogany-western juniper (J. occidentalis)
in San Bernardino Mountains
Sierra lodgepole pine-limber pine (P. contorta var. murrayana-P. flexilis)-curlleaf mountain-mahogany in San Bernardino Mountains [136]
western juniper/curlleaf mountain-mahogany
in Lava Beds National Monument [57]
curlleaf mountain-mahogany/bluebunch wheatgrass
curlleaf mountain-mahogany/Wyoming big sagebrush-mountain
snowberry (Artemisia tridentata ssp. wyomingensis-Symphoricarpos oreophilus)/
bluebunch wheatgrass
Utah juniper-Colorado pinyon (P. edulis)-curlleaf mountain-mahogany [13,14]
Idaho:
curlleaf mountain-mahogany/arrowleaf balsamroot/bluebunch wheatgrass [170]
curlleaf mountain-mahogany/bluebunch wheatgrass in upper foothills of
Snake River Plain [84], in the Sawtooth, White Cloud, Boulder, and Pioneer
mountains [174], and in west-central Idaho [211]
Douglas-fir (Pseudotsuga menziesii)-curlleaf mountain-mahogany in Challis and northern open Rockies
physiographic regions [190]
Rocky Mountain juniper (J. scopulorum)-curlleaf
mountain-mahogany/mountain snowberry/bluebunch wheatgrass in Bear River and
Bannock ranges
singleleaf pinyon-curlleaf mountain-mahogany/bush oceanspray (H. dumosus)/basin wildrye (L.
cinereus) in Bear River Range
singleleaf pinyon-curlleaf mountain-mahogany/mountain snowberry-Oregon-grape (Berberis repens)/bluebunch
wheatgrass in the west-central and southern Albion Mountains
singleleaf pinyon-curlleaf mountain-mahogany/Sandberg bluegrass in west-central and southern Albion
Mountains [170]
singleleaf pinyon/curlleaf mountain-mahogany in eastern and central part of the
state [190]
curlleaf mountain-mahogany/basin wildrye in Owyhee Uplands of southwestern
Idaho, northeastern Nevada, and southeastern Oregon
curlleaf mountain-mahogany/pinegrass (Calamagrostis rubescens) and
curlleaf mountain-mahogany/pinegrass/Idaho fescue in Owyhee Uplands
curlleaf mountain-mahogany/big sagebrush/slender wheatgrass (Elymus trachycaulus)
in Owyhee Uplands
curlleaf mountain-mahogany/big sagebrush/Sandberg bluegrass in Owyhee Uplands
[45]
curlleaf mountain-mahogany vegetation type in Wasatch Mountains [161]
curlleaf mountain-mahogany/mountain big sagebrush (Artemisia tridentata ssp. vaseyana) [23,146]
curlleaf mountain-mahogany/bluebunch wheatgrass
curlleaf mountain-mahogany/chokecherry (Prunus virginiana) [146]
curlleaf mountain-mahogany communities in Ruby-East
Humboldt Mountains [119]
curlleaf mountain-mahogany/longflower snowberry (S. longiflorus) [146]
curlleaf mountain-mahogany/mountain snowberry in Whitehorse Mountains [45] and throughout Nevada [146]
curlleaf mountain-mahogany/Oregon-grape
limber pine-curlleaf mountain-mahogany [146]
singleleaf pinyon-curlleaf mountain-mahogany throughout Nevada and
singleleaf pinyon-curlleaf mountain-mahogany/longflower snowberry/arrowleaf balsamroot in Eureka County [22]
western juniper-curlleaf mountain-mahogany/bluebunch wheatgrass
western juniper-curlleaf mountain-mahogany-mountain snowberry
white fir (Abies concolor)-ponderosa pine/curlleaf mountain-mahogany
[146]
Mountain-mahogany-oak vegetation association in
northwestern mountains [82]
curlleaf mountain-mahogany type in the Eagle Cap Wilderness in Wallowa Mountains [35]
and in Granite Creek Canyon in Wallowa-Whitman National Forest [97]
curlleaf mountain-mahogany/common snowberry (Symphoricarpos albus)/
Idaho fescue in Blue Mountains and in Basin and Range Province [45]
curlleaf mountain-mahogany/Idaho fescue and curlleaf mountain-mahogany/Idaho
fescue-bluebunch wheatgrass in northern Lake County
ponderosa pine/curlleaf mountain-mahogany/Idaho fescue in northern Lake County [44]
western juniper/curlleaf mountain-mahogany/elk sedge (Carex geyeri) in central and southern Blue and Ochoco
mountains [54]
curlleaf mountain-mahogany/big sagebrush/Idaho fescue in Basin and Range
Province
curlleaf mountain-mahogany/mountain snowberry/Sandberg bluegrass in Basin and Range Province [45]
curlleaf mountain-mahogany-grass in Blue Mountains of eastern Oregon and
southeastern Washington [77]
Douglas-fir/curlleaf mountain-mahogany on Wasatch Plateau [238], in Wasatch Range, and
in the Stansbury Mountains [128]
limber pine/curlleaf mountain-mahogany in the Wasatch Range [128]
ponderosa pine/curlleaf mountain-mahogany on Tavaputs, Maragut, and Sevier
plateaus and in the Pine Valley Mountains [238]
Utah juniper (Juniperus osteosperma)-curlleaf mountain-mahogany/bottlebrush squirreltail (Elymus
elymoides) in Bonneville Basin
Utah juniper-curlleaf mountain-mahogany/alkali wildrye (Leymus simplex)
in Bonneville Basin
Utah juniper-curlleaf mountain-mahogany/Sandberg bluegrass
in Bonneville Basin
singleleaf pinyon (Pinus monophylla)-curlleaf mountain-mahogany/arrowleaf balsamroot (Balsamorhiza
sagittata)-Sandberg bluegrass in Bonneville Basin [230]
white fir/curlleaf mountain-mahogany on Wasatch and Tavaputs plateaus and in the
Pine Valley Mountains [238]
curlleaf mountain-mahogany/bluebunch wheatgrass in Big Horn National Forest
curlleaf mountain-mahogany/true mountain-mahogany in Wyoming Basin
curlleaf mountain-mahogany-skunkbush sumac (Rhus trilobata) in Big Horn
Mountains
Douglas-fir/curlleaf mountain-mahogany in Bridger-Teton National Forest
Rocky Mountain juniper-curlleaf mountain-mahogany in Snake River Range
Rocky Mountain juniper/ponderosa pine/curlleaf mountain-mahogany in Black Hills [36]
Utah juniper-curlleaf mountain-mahogany in Big Horn Mountains [36,48]
Stand dynamics/relationships:
As stands in western and central Nevada reached 250
to 300 years of age, researchers noted a sharp reduction in stand density. Density of
the youngest individuals decreased as curlleaf mountain-mahogany age increased. Seedlings,
juveniles, and immature plants are 1st to be affected by increases in
mature curlleaf mountain-mahogany
size [177].
Browsing:
Many researchers indicate
that curlleaf mountain-mahogany decreases with browsing [112,153,219];
however, Parker [153] suggests that on some soils, which are not
described, curlleaf mountain-mahogany may increase with browsing. Browsing was simulated by clipping 90% of
the previous-year growth on 4 year-old shrubs near
Logan, Utah. Plants were clipped in either December or April. Clipped shrubs
produced more biomass than unclipped shrubs when
measured the following July. Differences were not significant [222].
In another Logan study, all the stems of 3-year-old established curlleaf mountain-mahogany seedlings
were clipped in the spring to 0.49 foot (0.15 m) and monitored for 3 seasons at the Utah
State University Research Farm. In the 1st year of treatments, height was
significantly (p<0.05) greater for unclipped plants. In the 2nd year of
treatments curlleaf mountain-mahogany height and crown area were significantly
(p<0.01 and p<0.05, respectively) greater for unclipped plants.
Ninety percent of the curlleaf mountain-mahogany plants survived the clipping treatments [168].
Pruning, girdling, dozing:
In the late 1970s and 1980s, researchers attempted to increase wildlife browse
by pruning, girdling, and dozing decadent curlleaf mountain-mahogany stands. Girdling was typically
ineffective and increased curlleaf mountain-mahogany mortality; pruning rarely produced long-term
increases in production; dozing increased the number of seedlings, but
increases in production were short lived. The following references provide
information on the benefits and drawbacks of pruning, girdling, and/or dozing
treatments in curlleaf mountain-mahogany stands [9,10,15,207]. In the Manti-LaSal National Forest,
Utah, curlleaf mountain-mahogany plants
pruned in late fall or winter (November-January) died, but annual growth was greater
for trees pruned in the spring or fall than for unpruned trees. For more
information see [206].
Predictive equations:
Several predictive volume, biomass, and age/height equations have been developed for
curlleaf mountain-mahogany. Researchers collected the largest curlleaf
mountain-mahogany stems from populations in
southeastern Oregon, northwestern Nevada, and central and northeastern Utah.
Stem size ranged from 1 to 9.8 inches (3-25 cm), and ages were 22 to 169 years. Developed
regression equations were only useful when
data came from the same population for which predictions were
being made [31]. In western and central Nevada, researchers found a linear relationship between
curlleaf mountain-mahogany
height and age. Greater average age was correlated with greater average height
[177]. Chojnacky [34] developed regression equations to
estimate curlleaf mountain-mahogany wood volume and biomass from data
collected from 3 sites in Nevada. Weaver [224] developed regressions of
curlleaf mountain-mahogany biomass against canopy
coverage and trunk diameter. Coverage/biomass regressions had the higher r²
values. Data for the equations came from a single site, so
equations would need modification for use outside of southwestern
Montana.
Native people utilized curlleaf mountain-mahogany. In a review, Conrad [38] indicates that the inner curlleaf mountain-mahogany bark made a purple dye and was used to treat lung ailments when boiled in a tea. Young plants dried, ground into powder, and mixed with water worked as a laxative. Fish spears, arrow shafts, and digging sticks were constructed from curlleaf mountain-mahogany wood [38]. Kawaisu people of south-central California boiled curlleaf mountain-mahogany bark and drank it daily while avoiding meat, grease, cheese, butter, and salt to treat gonorrhea. Plant exudate when dried and ground into a powder was used to relieve earaches [239]. Gosiute Indians of Utah used curlleaf mountain-mahogany wood in bow construction [198].
Recently curlleaf mountain-mahogany has been suggested as a heat and drought tolerant plant with potential in water-efficient landscaping [75]. Sutton and Johnson [202] described curlleaf mountain-mahogany as an "informal, large, picturesque, evergreen shrub for difficult dry spots."
Wood Products: Curlleaf mountain-mahogany wood is so hard that it quickly dulls chainsaws and axes and so dense that it sinks in water [26,46,80,214]. Curlleaf mountain-mahogany burns "long and hot" [198,214]. It was used for smelting ores in the 19th century [114], converted to coal in the past [235], and utilized as firewood by early western settlers [45]. Curlleaf mountain-mahogany's slow, hot burning character makes it a "prized barbeque fuel" [24] and good for smoking meats [46]. Contrasting heartwood and sapwood colors have been utilized in carvings [95,103]. Dealy [46] suggests curlleaf mountain-mahogany can be used for musical instruments, especially flutes. More in-depth information on the vessel and ray characteristics of curlleaf mountain-mahogany wood is available in [225].
Postfire sprouting by curlleaf mountain-mahogany is described as weak by most [11,76,126,236], but some consider curlleaf mountain-mahogany a nonsprouter [38]. Sprouts are typically only produced after low-severity fires. Curlleaf mountain-mahogany typically suffers "serious damage from all but the coolest of burns" [158]. In reviews, Neuenschwander [145] and Young [236] indicate that postfire sprouts typically die by the 2nd or 3rd postfire growing season. Sprouts from curlleaf mountain-mahogany plants with a treelike growth form are uncommon [145]. True mountain-mahogany à curlleaf mountain-mahogany hybrids are more fire tolerant than curlleaf mountain-mahogany [156].
Curlleaf mountain-mahogany is typically absent from areas with frequent fire [38], and curlleaf mountain-mahogany abundance on burned sites is nearly always lower than on unburned sites [127]. In the Petersen and Bald mountain ranges of California and Nevada, curlleaf mountain-mahogany mortality is almost always 100% following fire [166].
Curlleaf mountain-mahogany recolonizes burned sites predominantly through seedling establishment [71]. Seeds in the soil may survive low- or moderate-severity fires [71,98]. If the curlleaf mountain-mahogany seed bank and all nearby mature trees are consumed in the fire, curlleaf mountain-mahogany recolonization will depend on an off-site seed source and will be slow [27,39,147,158].
Curlleaf mountain-mahogany reproduces predominantly by seed. Sprouting occurs to "some extent" from the trunk base following cutting, but sprouts are rare after fire [212].
Regeneration variability: Several studies indicate that the number of seedlings in a given stand is highly variable, suggesting that the necessary conditions for successful seed germination, emergence, and establishment do not co-occur regularly. Of 22 curlleaf mountain-mahogany stands in southwestern Montana, only 7 had seedlings [53]. Reproduction was considered poor in 19 curlleaf mountain-mahogany communities scattered throughout Utah. Forty-seven percent of the plots had no seedlings. Seedling density ranged from 0 to 230 seedlings/acre and averaged 37/acre. Variable seed production and/or lack of conditions favorable to germination and establishment may have contributed to poor regeneration. However, periodic failure to regenerate may not be important for this long-lived (over 700 years) plant [40,42].
Pollination: Flowers are chiefly wind pollinated, although some pollination by insects may occur [108,129,152].
Breeding system: A review reports that outcrossing is most common and selfing is limited in mountain-mahogany species [129].
Seed production: Mountain-mahogany species are reproductively mature at 10 to 15 years old [108]. Good seed crop production is irregular. Researchers suggest that good curlleaf mountain mahogany seed crops are produced at 2- to 10-year intervals [157,179]. A single tree can produce 90,000 to 100,000 seeds in a year [46]. During a 2-year study of 22 curlleaf mountain-mahogany stands in southwestern Montana, seed production was abundant in 1 year and lacking in the other [53].
Seed production was cyclic in 2 curlleaf mountain-mahogany populations in central Oregon. High seed production occurred in 3 of the 12 years the populations were monitored, and good seed production years did not coincide in the widely separated populations. During high production years, seed piles were up to 9.8 inches (25 cm) deep in "rocky pockets;" however, seed predation by an unidentified insect was severe. Nearly 100% of seeds were damaged in heavily concentrated areas. In areas where seed was scattered, 90% escaped predation, but scattered seeds made up a small proportion of the total [45,47].
Seed dispersal: Curlleaf mountain-mahogany seed is moderately heavy and predominantly wind dispersed [108,236]. The feathery seed tail aids in wind dispersal [169]. Small mammals feed on the seeds and may serve as dispersal agents as well [129,157,179].
Researchers studied seed production, seed fall, seed predation, and seed redistribution in curlleaf mountain-mahogany stands in northeastern Utah. Initially most seed was under the curlleaf mountain-mahogany canopy and the fewest seeds occurred in the open interspaces. However, differences between the quantity of seed initially deposited under curlleaf mountain-mahogany, under other shrubs, or in the open interspaces were less than differences in these microhabitats when measured the following growing season. Seed predation, which was greatest in the open interspaces and lowest under curlleaf mountain-mahogany canopies, and/or secondary seed movement by wind or snow likely affected seed distribution changes. Overall, however, seed predation was low in the study area. Seed loss was 1% when all predators were excluded, 3% when only small mammals were excluded, and 8% when seed was unprotected. Predation levels were higher in the year with lower seed production than in the year with greater seed production, suggesting that seed survival may be density dependent [169].
Seed banking: Studies on the longevity of curlleaf mountain-mahogany seed in the soil under field conditions are lacking. Reports of high predation levels [47,179] suggest that predator avoidance is a necessary 1st step in seed bank building.
Curlleaf mountain-mahogany seed viability was not compromised after 10 years of storage in an open warehouse, and some seed still germinated after 25 years of storage. Temperature extremes of -21.8 °F (-29.9 °C) and 101 °F (38.3 °C) were recorded in the warehouse over the 25-year study period. Curlleaf mountain-mahogany germination from seed stored between 2 and 10 years did not differ significantly (p<0.05). Germination was a high of 80% after 5 years of storage and a low of 63% after 3 years of storage. Seed stored for 20 years had 44% germination, and germination after 25 years of storage was 28% [195].
Germination: Seeds require cold moist stratification and germinate best on mineral soil [27,41]. Germination typically increases with increased cold exposure [19,45,47,107]. Dealy [46] suggests that the persistent plume on seeds curls and straightens with humidity changes and effectively drills the seed into the ground, while temperature changes, moisture, and bacteria break down the seed coat.
Several studies report the germinability of seed collected in the field. Germination was enhanced by cold stratification. Seventy-six percent of cold stratified curlleaf mountain-mahogany seed collected in southwestern Montana germinated, and 50% produced cotyledons [53]. Current-year and 2-year-old seed collected near the high desert steppe zone in central Oregon averaged 74% and 78% viability, respectively. Unstratified seeds did not germinate, and seeds stratified for 60 and 170 days in dark at 40 °F (4 °C) had germination percentages of 20% and 98%, respectively. Seeds planted in containers, left outdoors in the fall to stratify naturally averaged 24% germination. Germination started on 14 April when soil moisture levels were high and temperatures were cool [45,47].
Elevation was not an indicator of cold stratification length for seed collected from 6 populations in Utah, Idaho, and Nevada. Seeds were kept moist in blotters. Chilling treatments were at 30 °F (1 °C) then followed by 59 °F (15 °C). Without chilling, germination was 0.5%. After 4 weeks of chilling germination was 32.2%, after 6 weeks was 76.3%, after 8 weeks was 91.7%, after 10 weeks was 96.0% and after 12 weeks was 98% [107].
Numerous seed treatments were tested on seed collected in Nevada. Neither dry heat treatments nor seed tail burning, which charred the achene, enhanced curlleaf mountain-mahogany seed germination. Decreases were not reported either. Feathery plumes ignited easily, and achenes remained intact after this type of burning. Seeds rarely germinated at temperatures other than 50 to 59 °F (10-15 °C). Germination increased some with storage. Germination was 2% two months after collection and increased to 17% at 6 months after harvest. Soaking in water enhanced germination [234].
Seedling establishment/growth: Depth of litter, denseness of shade, distance to established vegetation, and severity of browsing can affect curlleaf mountain-mahogany seedling emergence, establishment, and/or growth. Often times site characteristics that are conducive to seedling emergence are less conducive to seedling establishment and/or plant maturation.
Observational and ecological studies indicate that curlleaf mountain-mahogany seedlings are sensitive to drought, frost, and interference from nonnative vegetation, especially cheatgrass (Bromus tectorum) [157,179]. Ross [166] indicates that seedling recruitment is good on disturbed sites near the California-Nevada border. In Oregon and adjacent areas, seedling establishment was rare under mature curlleaf mountain-mahogany trees, but researchers reported that seeds outside the canopy had a "good opportunity for establishment" [45].
Initial resource allocation is to the roots of developing seedlings [41]. Newly established plants typically have a deep taproot and a small crown [114]. Twenty-four seedlings grown in a greenhouse that mimicked spring conditions in central Oregon's curlleaf mountain-mahogany habitats had an average taproot extension of 1.1 feet (0.34 m) after 35 days. After 112 days, the average seedling root length was 37.2 inches (94.5 cm), and average stem diameter was 0.029 inch (0.074 cm). Plants with the largest stem diameter usually had the longer root systems, but the same was not true regarding height [47,203].
Herbivory: Browsing can result in heavy seedling mortality or suppressed growth. In 17 curlleaf mountain-mahogany stands in southern and central Idaho, there were an average of 1.9 seedlings/ft². Seedling survival through the 1st summer was 28%. Of the surviving seedlings, 25% without protection from browsing animals survived, 45% protected from big game animals survived, and 50% protected from all browsers survived. Researchers attributed substantial mortality to mountain cottontails. Four- to five-year-old plants were only 1 to 2 inches (3-5 cm) tall due to heavy browsing. Two juvenile growth forms referred to "basketball- and umbrella-shaped" resulted from the heavy browsing pressure. Basketball shrubs measured only 3 to 4 feet (0.9-1 m) tall at 60 to 70 years of age. Umbrella shrubs had 1 main stem and no low branches [173]. Dealy [44] suggests that successful seedling establishment in curlleaf mountain-mahogany/Idaho fescue habitats with heavy deer use may be a result of seedlings being undetected among bunchgrasses and in snow until they reach 6 to 12 inches (20-30 cm), when a well-developed root system and numerous branches increase curlleaf mountain-mahogany's resiliency.
Site characteristics: A number of studies report on the importance of shallow litter depths and open canopies in the successful emergence and establishment of curlleaf mountain-mahogany seedlings. While seeds emerged successfully in deep litter substrates, establishment was rare. Establishment was more successful on low litter or bare mineral soil substrates outside of the curlleaf mountain-mahogany canopies.
Curlleaf mountain-mahogany seedlings were most common in the deep duff and litter (>5 inches (13 cm)) under and near mature trees in south-central Utah. However, seedlings in the deep duff lacked a main taproot, and fewer seedlings established in the deep litter than in the open sites with shallow litter layers (<4 inches (10 cm)). Four- to five-year-old seedlings were 4 to 10 inches (10-30 cm) tall, while 20-year-old seedlings were 2 to 3 feet (0.6-0.9 m) tall [207]. Regeneration was low in closed-canopy curlleaf mountain-mahogany stands in Idaho, Montana, and Nevada. Shading, litter, and absence of bare mineral soil were suggested as possible barriers to successful seedling establishment. No seedlings over 2 years old were found on sites with litter depths greater than 0.25 inch (0.63 cm). Open-canopy stands were "regenerating at a sustained rate" [71].
In northeastern Utah's Cache National Forest, survival of 6-week-old seedlings in open interspaces, under big sagebrush, and beneath curlleaf mountain-mahogany was compared. Survival was low in the interspaces in a dry year, but good in a wet year, especially when herbivory was excluded. Findings stressed the importance of interactions between microhabitat and environmental conditions in seedling establishment [90]. In the same area, researchers found that emergence was significantly (p<0.10) better on soils without litter than those with litter. However, seedling survival was significantly greater on sites with litter than those without. Emergence was best in the open interspaces, with sparse litter and adequate light and temperatures. Establishment was best in the litter under curlleaf mountain-mahogany trees. Researchers thought that seedlings experienced moderated temperatures, increased moisture, and some herbivore protection under the canopy. Findings suggested that seedling establishment would be successful in the open interspaces when conditions were wet and herbivory was low. However, seedlings that established under trees may not reach maturity [91,92].
Twenty-five curlleaf mountain-mahogany stands were studied in western and central Nevada. Seedling production ranged from zero to abundant. Reproduction was abundant only on sites with an open canopy. Poor seedling establishment and survival in old (>500 years) stands with high curlleaf mountain-mahogany cover and crown volume was likely due to seedling root development. In deep litter, roots rarely extended into the mineral soil, and seedlings dried out and died. Under a closed canopy, seedlings rarely grew beyond 0.3 inch (7 mm) in basal diameter. Some curlleaf mountain-mahogany plants that were only a few inches tall were aged to over 30 years. Researchers predicted that the suppressed juvenile plants in the overstory would come to occupy gaps created in the overstory through mortality [175,176,177].
Significantly (p<0.05) more current-year seedlings occurred in the curlleaf mountain-mahogany stands, but significantly more established seedlings and juveniles occurred in nearby sagebrush (Artemisia spp.) communities in the Shoshone Range in Nevada. Fewer immature curlleaf mountain-mahogany plants (5) were found in curlleaf mountain-mahogany stands than in big sagebrush communities (21), but differences were not significant. Curlleaf mountain-mahogany seedlings in curlleaf mountain-mahogany stands had extensive root growth up to 6 inches (20 cm), but growth was largely lateral in litter layer. Rarely did roots reach the mineral soil [178].
Asexual regeneration: Curlleaf mountain-mahogany asexual regeneration is limited. Sprouting may occur after "light" fires [71], but typically sprouts do not live beyond the 2nd or 3rd postfire year [145]. Plants in southwestern Montana that were approximately 15 feet (4.5 m) tall and pruned to 3 foot (1 m) heights sprouted new growth when at least 1 stem was left on the cut plants. Cut stems ranged from 2 to 5.9 inches (5-15 cm) in diameter. Increase of annual biomass on uncut plants was140 g/plant and on cut plants was 436 g/plant [151].
Curlleaf mountain-mahogany functions as a late-seral or a mid-seral species in most communities. Site conditions likely dictate curlleaf mountain-mahogany's place in succession. Curlleaf mountain-mahogany's shade tolerance is low [26,113,159], so if sites can support coniferous species, curlleaf mountain-mahogany may be replaced as conifers dominate the canopy. However, succession proceeds at an "extremely slow" rate in many curlleaf mountain-mahogany communities [40,42], and long-term studies of successional change in curlleaf mountain-mahogany communities are lacking.
Late-seral: The age structure of many curlleaf mountain-mahogany stands in Idaho, Montana, and Nevada suggests that curlleaf mountain-mahogany is a potential late-seral species [53,71]. Curlleaf mountain-mahogany persists in old-growth Douglas-fir/curlleaf mountain-mahogany stands in Utah and Idaho [128]. On the warmest, driest forest sites in eastern Oregon and Washington, curlleaf mountain-mahogany is a late-seral species with ponderosa pine [96]. Curlleaf mountain-mahogany is also considered a codominant species in late-seral Rocky Mountain juniper-limber pine forests of Montana [167]. In southwestern and south-central Montana, curlleaf mountain-mahogany plants ranged from 2 to 130 years old, and recruitment was relatively good. Because curlleaf mountain-mahogany is long lived, researchers expected curlleaf mountain-mahogany to remain in the community for a long time in the absence of disturbance [122]. Of the 19 curlleaf mountain-mahogany communities surveyed and studied throughout Utah, the majority were late-seral or stable communities; however, in 2 communities, researchers expected white fir to replace curlleaf mountain-mahogany [40,42].
Seral: Several sites in Idaho, Montana, and Nevada also supported communities in which curlleaf mountain-mahogany was seral to conifers. Researchers considered curlleaf mountain-mahogany replacement inevitable without some disturbance in stands where conifers were successfully reproducing [71]. In mountain shrub vegetation in Utah's Wasatch Mountains, curlleaf mountain-mahogany "occupies rocky ridges, represents a stage in xeric site succession, and is not a late-seral type" [81]. In southeastern Idaho, singleleaf pinyon and Rocky Mountain juniper regeneration in the understory of curlleaf mountain-mahogany communities suggested that singleleaf pinyon and Rocky Mountain juniper were the late-seral species. The same was not observed in places where curlleaf mountain-mahogany was growing adjacent to Utah juniper stands [170]. In southeastern Oregon and southeastern California, 2 curlleaf mountain-mahogany stands under a closed western juniper canopy were over 90% dead, suggesting that curlleaf mountain-mahogany was seral to western juniper in the area [135]. Curlleaf mountain-mahogany is an important mid-seral species in Douglas-fir/ninebark (Physocarpus malvaceus) and Douglas-fir/Rocky Mountain maple (Acer glabrum) habitat types in central Idaho [189].
Fire: Increases in curlleaf mountain-mahogany abundance are often attributed to decreased fire frequency [62,72,74,94]. Curlleaf mountain-mahogany recolonization can be quick if seed in the soil is unharmed, but postfire establishment can take several decades following severe fires that destroy the seed bank and kill parent plants [71]. Ross [166] presents state and transition successional models for curlleaf mountain-mahogany stands studies in the Petersen and Bald mountain ranges on the California-Nevada border. Disturbances highlighted in the models are those that have been most influential on the area in the past 55 years. The successional model for the Bald Mountain range incorporates fire, red-breasted sapsucker damage, woodcutting practices, and conifer canopy development, while the model of successional change in the Petersen Mountains is driven by fire as the chief disturbance process [166]. See Birds for more about curlleaf mountain-mahogany and the red-breasted sapsucker.
Logging: Curlleaf mountain-mahogany established immediately after sites were logged in Idaho [71] and on the California-Nevada border [166].
The scientific name of curlleaf mountain-mahogany is Cercocarpus
ledifolius Nutt. (Rosaceae) [83,86,102,105,113,228]. The following varieties
are recognized, although not consistently:
C. l. Nutt. var. intercedens Schneider [52,85,86,102,105,125]
C. l. Nutt. var. intermontanus Holmgren [83,87,102,201]
C. l. var. ledifolius Nutt. [52,83,86,87,102,125,201]
Stutz [201] suggests that C. l. var. ledifolius and
C. l. var. intercedens are not distinct and describe the same plant. Stutz recognizes
varieties C. l. var. ledifolius and C. l. var. intermontanus. Hickman [83]
and Holmgren [87] suggest that C. l. var. intercedens is actually
a hybrid of C. l. var. intermontanus and littleleaf
mountain-mahogany (C. intricatus). Due
to the lack of agreement in infrataxa recognition, varieties are not
distinguished in most sections of this review.
Curlleaf mountain-mahogany hybridizes with littleleaf mountain-mahogany and
true mountain-mahogany (C. montanus) where distributions of the species overlap
[24,41,201,228]. Descriptions of hybrid traits and habitats are available
[24,28,200,221].
Researchers consider curlleaf mountain-mahogany a valuable component in revegetation or reclamation efforts. Seed and/or plants are commercially available for restoration or revegetation [8,215]. Curlleaf mountain-mahogany provides soil stabilization [130,159], fixes nitrogen [139], and provides important wildlife browse and cover [193]. Establishment can be very slow, however, and sites may require protection from livestock, humans, and/or native browsers for 4 to 6 years for successful establishment [194].
Site conditions and community types within the Intermountain West that are best suited for curlleaf mountain-mahogany revegetation are provided in [191]. Curlleaf mountain-mahogany is listed as a "preferred" plant for highway plantings in Nevada's pinyon-juniper vegetation zone. Optimal planting time and proper site selection in the pinyon-juniper zone are discussed in [186]. Researchers suggest that curlleaf mountain-mahogany may also be useful for the reclamation of Utah's semiarid pinyon-juniper zone [60].
Many references provide specific information on the use of curlleaf mountain-mahogany in revegetation projects from seed collection to monitoring success. See [192] for information on the use of bareroot stock and container plants. Monsen and Stevens [139] provide methods for seeding curlleaf mountain-mahogany including information on seedling growth rate, vigor, and compatibility with other vegetation. Curlleaf mountain-mahogany seed collection, cleaning, and storage information is available in [99]. More information on the successful use of curlleaf mountain-mahogany in revegetation, restoration, or reclamation efforts is available in [179,196,220].
Survival on reclaimed sites: Curlleaf mountain-mahogany's survival on roadside cuts, poorly vegetated riversides, and mine sites has been variable. On the south Fork of the Payette River in Boise County, Idaho, curlleaf mountain-mahogany only survived on sites that remained free of weeds after planting. Sites were disked in 1949, and curlleaf mountain-mahogany survival was just 10%. Plants averaged 2.5 inches (6.3 cm) tall in the 3rd year after planting [88]. Revegetation of western Montana road cuts that are outside of curlleaf mountain-mahogany's natural range were evaluated 4 years after planting. Curlleaf mountain-mahogany plants were in "less than satisfactory condition" at the time of spring planting. Just 7% of 29 curlleaf mountain-mahogany plants survived, but surviving plants were described as "established and in good condition" 9 years after planting. Researchers rated curlleaf mountain-mahogany's growth, vigor, natural spread, and soil stabilization as moderate to very low [89]. One-year-old curlleaf mountain-mahogany seedlings planted on roadside cuts and fill slopes in Colville and Okanogan National Forests of eastern Washington averaged 42%. Survival and vigor, based on plant size and color, were rated as good when plants were evaluated 2 years after planting [210].
Curlleaf mountain-mahogany was a "preferred" species in the revegetation of steep south-facing slopes of the Maybe Canyon phosphate mine near Soda Springs, Idaho [162]. On New Mexico's La Plata surface mine reclamation sites, curlleaf mountain-mahogany was the most utilized shrub. Newly planted sites were protected for 7 or 8 growing seasons. Curlleaf mountain-mahogany did not establish on all sites, and relative abundance averaged 0.3 plant/m² [231]. Curlleaf mountain-mahogany seedlings survived well for at least the first 3 years on 14-year-old sulfur mine spoils in northeastern California. Spoils were low in pH but did not have toxic levels of iron, manganese, copper, or zinc. Survival of curlleaf mountain-mahogany 10 months after planting was 97% and decreased only slightly to 91% three years after planting [33].
Cercocarpus ledifolius is a North American species of mountain mahogany known by the common name curl-leaf mountain mahogany. It is widespread across much of the Western United States as well as Baja California in Mexico.[2][3] It can be found at elevations ranging from 600 to 3,000 m (2,000 to 9,800 ft) elevation, with the preferred altitude varying depending on the region. It prefers shallow, well-drained soils with a sandy or grainy consistency, and is generally found in areas which receive low annual precipitation (15–26 cm).[4] This makes it common on low mountains and slopes,[5][3] where it grows in scattered groves among other drought-resistant species such as Pinyon Pines, Junipers and Sagebrush ecosystems.
Cercocarpus ledifolius is a large, densely branching tree which can reach heights of 11 m (35 ft), although it is not uncommon to find the adult plant as a shrub as short as 1 m (3 ft). Its leathery, sticky, dark green leaves are up to 4 centimeters (1.6 inches) long and lance-shaped, and the edges may curl under. The flower consists of a small tan tube from which protrudes a long, plumelike style covered in luxuriant tan hairs. The flowers are arranged in inflorescences of up to 3. The fruit is a hairy achene one half to just over one centimeter (0.2-0.4 inches) long.
Cercocarpus ledifolius is slow-growing, sometimes taking up to a century to reach full height. The oldest specimens are thought to be around 1,350 years old, although the primary specimen that yielded this estimate was cut down.[6] This makes it one of the longest lived known flowering plants.
The leaves are eaten by deer year-round.[7]
The Gosiute Native Americans used the wood to make their bows.[7] The species has many medicinal uses for various Native American groups, such as the Paiute and Shoshone.
Curl-leaf mountain mahogany branch with curly, fuzzy fruit Cercocarpus ledifolius is a North American species of mountain mahogany known by the common name curl-leaf mountain mahogany. It is widespread across much of the Western United States as well as Baja California in Mexico. It can be found at elevations ranging from 600 to 3,000 m (2,000 to 9,800 ft) elevation, with the preferred altitude varying depending on the region. It prefers shallow, well-drained soils with a sandy or grainy consistency, and is generally found in areas which receive low annual precipitation (15–26 cm). This makes it common on low mountains and slopes, where it grows in scattered groves among other drought-resistant species such as Pinyon Pines, Junipers and Sagebrush ecosystems.
