|
|
FEIS Home Page |
 |
 |
|
| Photos © James L. Reveal @ USDA-NRCS, PLANTS Database. | ||
AUTHORSHIP AND CITATION:
Groen, Amy H. 2005. Yucca glauca.
In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
https://www.fs.usda.gov/database/feis/plants/shrub/yucgla/all.html [].
FEIS ABBREVIATION:
YUCGLA
SYNONYMS:
Yucca angustifolia Pursh [70]
NRCS PLANT CODE [151]:
YUGL
YUGLG2
COMMON NAMES:
soapweed yucca
Great Plains yucca
small soapweed
TAXONOMY:
The currently accepted scientific name for soapweed yucca is Yucca glauca
Nutt. (Agavaceae) [39,40,49,57,70,91,137,161]. Varieties accepted by some authorities
include:
Y. g. var. glauca, narrowleaf yucca
Y. g. var.gurneyi McKelvey [70], Gurney's yucca
Throughout this review, soapweed yucca refers to all varieties of Y. glauca. A distinction between the varieties will only be made in the Distribution and occurrence section. The Flora of North America [49] does not recognize soapweed yucca varieties.
Hybrids: Soapweed yucca hybridizes with soaptree yucca (Y. elata) in eastern Colorado, central New Mexico, and Arizona [160,161]. Soapweed yucca is also believed to hybridize with Buckley's yucca (Y. constricta), Navajo yucca (Y. baileyi), and narrowleaf yucca (Y. angustissima) [160].
LIFE FORM:
ECOSYSTEMS [52]:
FRES15 Oak-hickory
FRES21 Ponderosa pine
FRES29 Sagebrush
FRES30 Desert shrub
FRES31 Shinnery
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
STATES/PROVINCES: (key to state/province abbreviations)
UNITED STATES
| AR | CO | IA | KS | MO | MT | NE |
| NM | ND | OK | SD | TX | UT | WY |
| AB |
In the central Rocky Mountains of Colorado soapweed yucca is found in areas dominated by interior ponderosa pine (Pinus ponderosa var. scopulorum). Other shrubs include fivepetal cliffbush (Jamesia americana), common juniper (Juniperus communis), bearberry (Arctostaphylos uva-ursi), wax currant (Ribes cereum), shrubby cinquefoil (Dasiphora floribunda), and Wood's rose (Rosa woodsii) [120]. Along the Colorado Front Range it is associated with the New Mexico feathergrass (Hesperostipa neomexicana) community, where it is present with purple threeawn (Aristida purpurea), foothill milkvetch (Astragalus tridactylicus), Front Range twinpod (Physaria bellii), and shortstem buckwheat (Eriogonum brevicaule) [105]. Soapweed yucca is also found in tree cholla (Opuntia imbricata) associations with blue grama, sand dropseed (Sporobolus cryptandrus), and ring muhly (Muhlenbergia torreyi) [77], and in Colorado pinyon-juniper (Pinus edulis-Juniperus spp.) dominated systems [31].
Throughout Kansas soapweed yucca can be found with prairie graminoids such as little bluestem (Schizachyrium scoparium), blue grama, and needle-and-thread grass. Shrub associates include sand sagebrush and fourwing saltbush (Atriplex canescens) [83]. Soapweed yucca is found with velvetweed (Gaura mollis), nineanther prairie clover (Dalea enneandra), and hairy grama (Bouteloua hirsuta) in shortgrass prairie habitats [2] and with little bluestem, big bluestem (Andropogon gerardii var. gerardii), purple prairie clover (Dalea purpurea), azure blue sage (Salvia azurea), and western ragweed (Ambrosia psilostachya) in tallgrass prairie habitats [114].
Soapweed yucca is associated with open, dry habitat types in Montana. It occurs in interior ponderosa pine and limber pine (Pinus flexilis) stands with blue grama, sideoats grama (Bouteloua curtipendula), and plains prickly-pear (Opuntia polyacantha) [5], and can be found with skunkbush sumac (Rhus trilobata) and creeping juniper (Juniperus horizontalis) in the interior ponderosa pine/bluebunch wheatgrass (Pseudoroegneria spicata) vegetation type [45]. In the badlands of southeastern Montana, soapweed yucca is found with greatest frequency in the mountain big sagebrush-western wheatgrass (Pascopyrum smithii) community type and greatest abundance in the skunkbush sumac-western wheatgrass community type [25].
Soapweed yucca is found throughout most of Nebraska and is important for the ground coverage it provides in the Nebraska sandhill range [51]. It is commonly associated with sandy substrates, occurring on blowouts with sand bluestem (Andropogon gerardii var. paucipilus) and little bluestem [116], and on dune ridges and upper slopes with stiff sunflower (Helianthus pauciflorus), leadplant (Amorpha canescens), prairie rose (Rosa arkansana) [13], western sandcherry (Prunus pumila var. besseyi), and manystem pea (Lathyrus polymorphus) [12]. Soapweed yucca is found with western snowberry (Symphoricarpos occidentalis) and skunkbush sumac [149] on scattered and open woodlands and with blue grama, threadleaf sedge (Carex filifolia), and western wheatgrass in mixed-prairie habitat types [163].
In the high plains of Nebraska, soapweed yucca was found on 8 out of 9 surveyed plots. Relative abundance of soapweed yucca was highest on isolated canyon slopes, where it could be found with Rocky Mountain juniper (Juniperus scopulorum), eastern redcedar (Juniperus virginiana), and little bluestem. Soapweed yucca was also found on sand talus with big bluestem, little bluestem, needle-and-thread grass, and sagebrush (Artemisia spp.) [71].
In the middle Rio Grande valley of New Mexico, soapweed yucca occurs with soaptree yucca, tree cholla, and broom snakeweed (Gutierrezia sarothrae). Grasses in these desert grassland plant communities include black grama (Bouteloua eriopoda), big galleta (Pleuraphis rigida), burrograss (Scleropogon brevifolius), and threeawns (Aristida spp.) [86]. In the shrub-grassland areas, soapweed yucca occurs with velvet mesquite (Prosopis velutina), broom snakeweed, and sand shinnery oak (Quercus havardii). In the desert grasslands of northeastern New Mexico it is found primarily with blue grama, sideoats grama, and galleta (Pleuraphis jamesii) [44].
Soapweed yucca in the Dakotas can be found at the easternmost edge of interior ponderosa pine habitat with skunkbush sumac, western poison-ivy (Toxicodendron rydbergii), and chokecherry (Prunus virginiana) [66]. It occurs with prairie sandreed on less than 3 acres (1 ha) in Badlands National Park [36], and is associated with the sand bluestem-prairie sandreed habitat type in southwestern North Dakota [65]
Throughout its distribution in Texas, soapweed yucca is broadly associated with sand sagebrush and prickly-pear (Opuntia spp.) [9,154,155] and can also be found with redberry juniper (Juniperus erythrocarpa), Ashe juniper (J. ashei), sideoats grama, hairy grama, and blue grama [136]. It occurs with honey mesquite (Prosopis glandulosa), catclaw acacia (Acacia greggii), wait-a-minute (Mimosa aculeaticarpa var. biuncifera), and lotebush (Ziziphus obtusifolia) [98], and can reach densities exceeding 2,000 plants per acre on the panhandle of northern Texas [93]. Its occurrence in western Texas is not significantly (P<0.05) affected by the occurrence of Pinchot juniper (Juniperus pinchotii) [99].
In western Missouri soapweed yucca is found in prairie habitats with hairy grama, blue grama, large beardtongue (Penstemon grandiflorus), and downy paintbrush (Castilleja sessiliflora) [147]. In western Iowa it occurs with little bluestem, big bluestem, and purple coneflower (Echinacea angustifolia) [128].
Soapweed yucca can be found on east-facing slopes of the Big Horn mountains of Wyoming with little bluestem and bluebunch wheatgrass [34]. It can be found in the Powder River Basin with Wyoming big sagebrush (Artemisia tridentata var. wyomingensis), western wheatgrass, blue grama, and birdfoot sagebrush (Artemisia pedatifida) [48]. Soapweed yucca is often found with blue grama and sagebrush, with highest coverage and constancy percentages in shrub-steppe vegetation types [146]. At the Great Sand Dunes National Monument, it was found on 21% of research plots located on active and stabilized dunes [94].
Soapweed yucca is found with Rocky Mountain juniper and Colorado pinyon in juniper-pinyon woodlands that occur throughout the Great Basin. Other associates include Stansbury cliffrose (Purshia mexicana var. stansburiana), Apache-plume (Fallugia paradoxa), green ephedra (Ephedra viridis), Fremont's mahonia (Mahonia fremontii), fourwing saltbush, and banana yucca (Yucca baccata) [23]. In the Great Basin grasslands soapweed yucca is found with sacahuista (Nolina microcarpa), skunkbush sumac, wait-a-minute, and fourwing saltbush [123].
Shrubs such as soapweed yucca, fourwing saltbush, winterfat (Krascheninnikovia lanata), prairie sumac (Rhus copallinum var. lanceolata), rabbitbrush (Chrysothamnus spp.), and snakeweed (Gutierrezia spp.) are scattered throughout the plains grasslands. In areas subjected to heavy grazing, soapweed yucca is found with honey mesquite, sand shinnery oak, and sand sagebrush [24]. In the northern prairie wetlands region it can be found on blowouts with sand bluestem, hairy grama, and needle-and-thread grass in areas where there is no contact with the water table [108].
|
 |
| Photo © James L. Reveal @ USDA-NRCS, PLANTS Database. |
Soapweed yucca is a native evergreen shrub [70] that grows to 3 feet (1 m) in height [137]. It supports short, branching, decumbent stems [91] and a taproot [142,143]. Root systems greater than 20 feet (6 m) in depth were reported in eastern Colorado [96]. Lateral roots extend 20 to 30 feet (6-9 m) [158]. Soapweed yucca supports 1 or 2 large diameter rhizomes from which a network of smaller oblique rhizomes protrude, forming a mat 4 to 24 inches (10 to 60 cm) below the soil surface [160].
Soapweed yucca has simple, concave, alternate leaves with coarse fibers along the margins and a sharp apex [137]. Leaf size ranges from 8 to 40 inches (20-100 cm) in length and 0.2 to 0.5 inch (0.6-1.2 cm) in width [91]. Leaves emerge from a woody caudex [39] and are situated at a steep angle that allows year-round photosynthesis [89]. Stomatal conductance and net photosynthesis are adapted to function at optimal capacity under given temperatures [124]. The appearance of the leaf head of soapweed yucca is contingent upon its age and available rainfall [160].
Soapweed yucca has a raceme inflorescence [57] that is nearly sessile, 12 to 80 inches (30-200 cm) in length [61], and composed of 25 to 30 drooping flowers [137]. Fruits are oblong, dehiscent, erect, and approximately 1.2 inch (3 cm) in length [61]. Soapweed yucca flowers house a single style and 6 stamens [40]. Seeds are glossy [151], and grow to 9 × 12 mm [49].
RAUNKIAER [119] LIFE FORM:Pollination: Pollination of soapweed yucca is dependent upon the yucca moth (Pronuba yuccasella) [165] or other pollinating insects such as small flies (Pseudocalliope spp.) [38]. The yucca moth transfers pollen from the anther, depositing it deep into the style and leading to the production of many seeds, some of which are fed upon by the larvae [38]. The number of yucca moths available for pollination is related to the abundance of open flowers [106].
Soapweed yucca benefits from wood ants (Formica spp.). They are natural predators of the nonpollinating yucca moth (Tegeticula corruptrix), which feeds on soapweed yucca seeds while in the larval stage [111].
Breeding system: Moth pollination [165] assures that soapweed yucca is mostly outcrossing. Anthers are remote from the cavity encapsulated stigma and sticky pollen [11], assuring that autogamous pollination of soapweed yucca is rare. Pollen is viable for a minimum of 4 days, as are the flowers. Autogamous pollination occurs as the flower begins to wilt and stamens come into direct contact with the stigma [38].
Seed production: The number of viable soapweed yucca seeds is dependant upon the transfer of high quality pollen, sufficient resources for development, and ovules that are not damaged by the insertion of the yucca moth's ovipositor during the transfer of pollen [1]. It can take several years for rosettes to bloom [79]. Despite the high number of seeds consumed by moth larvae, large numbers are left unharmed for dispersal [11].
In a study to determine the relationship between soapweed yucca and the yucca moth, 124 plants with a mean of 291 ovules per plant had 138 viable seeds after consumption by adult and larval yucca moths. The maximum number of larvae per fruit was 19 [1]. In Colorado, the number of surviving seeds increased with elevation despite fewer fruits. This was likely due to decreased predation by the yucca moth, which prefers the warmer temperatures of the Great Plains over those experienced at higher elevations [38].
Seed dispersal: Seed pods become erect and split longitudinally, exposing seeds to dispersal by wind and gravity [11].
Seed banking: Laboratory studies exploring germination rates of soapweed yucca suggest that seed banking is likely [38,149,160]. Further research is needed to determine longevity and viability of soapweed yucca seeds in a field setting.
Germination: Soapweed yucca experiences higher rates of germination when stratified. In a laboratory setting soapweed yucca successfully germinated under a variety of stratification treatments. Following 1 to 3 months of stratification, germination occurred after exposing seed to a constant 70 ºF (20 ºC) or alternating temperatures between 70 ºF (20 ºC) and 40 ºF (5 ºC). Germination also occurred after seed was stored at 40 ºF (4 ºC) and then exposed to 70 ºF (20 ºC) temperatures. A maximum of 27% of seeds germinated after being exposed to 90 ºF (30 ºC) or by alternating 90 ºF (30 ºC) and 70 ºF (20 ºC). Sixty-seven percent germination was achieved at 50 ºF (10 ºC) with 3 months stratification. The highest germination rates (91%) were experienced when 4-month-old seed was dry stored at 70 ºF (20 ºC) and then wet treated for 3 months at 70 ºF (20 ºC). Six days were required for 50% germination. See Emerson [43] for further seed germination information.
A study on the germination of Nebraska sandhill plants revealed 67.1% germination rates for soapweed yucca seed that had been dry stored, 44% germination for seeds vernalized for 1 month, and 86.6% germination for seeds vernalized for 2 months. Seed vernalized for 3 months sprouted while in storage under winter temperatures [149]. Soapweed yucca germinated in 4 days after being soaked in water for 24 hours and kept at temperatures between 80 ºF and 90 ºF (28 ºC and 32 ºC) in moist cotton [160]. Seeds from low-elevation soapweed yucca plants are thought to have stronger tendencies towards dormancy than those found at high elevations [38].
Seedling establishment/growth: Reproduction of soapweed yucca by seed is limited to the percentage of viable seeds remaining after seed predation by larvae. Soapweed yucca had the highest number of seedlings of 19 observed yucca species over a 4-year period, with 72 seedlings observed [160]. Soapweed yucca seedlings have reduced growth rates compared to ramets. Seedlings are important for colonizing new sites, after which clones take over as primary reproducers. As the carrying capacity is reached, seed production increases in order that new populations may emerge outside the range of vegetative reproduction. The ratio of seedlings produced vegetatively versus those produced by seed varies across populations [76].
Asexual regeneration: Soapweed yucca reproduces vegetatively through sprouting from the caudex and from horizontal rhizomes [38,160], which yield rosette-baring offshoots [11]. Projecting from the upper portion of one or two large diameter rhizomes are horizontal branches forming a netlike pattern from which sprouts emerge. Depriving the plant of shoots through fire or mechanical means results in regeneration rates that equal or exceed previous regeneration rates within a year or 2. In a study to confirm successful vegetative propagation, sprouts were separated from the mother plant by removing 2- to 4-inch (5-10 cm) sections of rhizome while in the field. Normal growth of the sprouts continued during the following year [160]. Vegetative reproduction can be stimulated after top-kill of soapweed yucca [93].
SITE CHARACTERISTICS:Soils: Soapweed yucca is most commonly found on sandy sites [27,32,65,134] or rocky areas with coarse-textured soils [43,146,161]. In the Great Plains it is associated with limestone soils [71,137] and alluvial terraces [105]. In New Mexico soapweed yucca is found in sandy soils underlain by caliche [33]. Soils in Texas are relatively deep clays or clay loams [98]. On the Colorado Front Range, soil pH is approximately 8.0 to 8.2 [105]. Soapweed yucca does best in well-drained soils with sunny exposures [135].
Elevation: Soapweed yucca tolerates a wide range of elevations:
| CO | 2,500 to > 8,500 feet (760-2,600 m) [38,92] |
| MT | 3,000 to 4,400 feet (900-1,300 m) [25] |
| NM | 3,600 to 6,500 feet (1,100-2,000 m) [86,91] |
| UT | 4,000 to 7,000 feet (1,200-2,100 m) [144] |
| Great Plains | 660 to 7,200 feet (200-2200 m) [73] |
Soapweed yucca can be found on undisturbed sites [32] and sites affected by land management activities [160] such as plowing [96]. It is a late-seral species on sandy range sites and in grassland associations (50% cover) in Montana [125]. In southeastern Montana, soapweed yucca is considered an understory species in the interior ponderosa pine/skunkbush sumac vegetation type [55], indicating possible shade tolerance. It also occurs on open sites [135].
SEASONAL DEVELOPMENT:Recently disturbed sites provide an opportunity for soapweed to germinate; however, germination rates of soapweed yucca seed decreased after being exposed to high temperatures (180-250 ºF (80-120 ºC)) in a laboratory setting [73]. This suggests that on-site seeds require burial in the seed bank in order to germinate following fire. Wind and gravity dispersal [11] of off-site seed sources is also possible after fire. Further research is needed to explore fire adaptations of soapweed yucca.
Fire regimes: Soapweed yucca is primarily associated with grassland environments. Historical fire return intervals within these vegetation types were probably dependant upon drought cycles, the prevalence of lightning strikes, and anthropogenic uses. Soapweed yucca is primarily found throughout ecosystems characterized by fire return intervals of less than 35 years [109]. Where fire has been excluded from sagebrush communities and desert grasslands, invasion of nonnative annual grasses such as red brome (Bromus madritensis ssp. rubens), lovegrass (Eragrostis spp.), and cheatgrass (Bromus tectorum) has often occurred, enhancing the potential for fires to start and spread, and increasing fire frequency [14,28,164,169]. Fire return intervals have also been reduced as a result of overgrazing which can lead to dense overstories forming closed canopies that carry fire more efficiently. Exotic annual grasses are likely to invade these sites if a seed source is available [112].
The following table provides fire return intervals for plant communities and ecosystems where soapweed yucca is important. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes".
| Community or Ecosystem | Dominant Species | Fire Return Interval Range (years) |
| bluestem prairie | Andropogon gerardii var. gerardii-Schizachyrium scoparium | <10 [78,109] |
| Nebraska sandhills prairie | Andropogon gerardii var. paucipilus-Schizachyrium scoparium | <10 |
| bluestem-Sacahuista prairie | Andropogon littoralis-Spartina spartinae | <10 [109] |
| silver sagebrush steppe | Artemisia cana | 5-45 [63,118,167] |
| sagebrush steppe | Artemisia tridentata/Pseudoroegneria spicata | 20-70 [109] |
| basin big sagebrush | Artemisia tridentata var. tridentata | 12-43 [127] |
| mountain big sagebrush | Artemisia tridentata var. vaseyana | 15-40 [8,26,101] |
| Wyoming big sagebrush | Artemisia tridentata var. wyomingensis | 10-70 (µ=40) [156,170] |
| saltbush-greasewood | Atriplex confertifolia-Sarcobatus vermiculatus | <35 to <100 |
| desert grasslands | Bouteloua eriopoda and/or Pleuraphis mutica | <35 to <100 [109] |
| plains grasslands | Bouteloua spp. | <35 [109,167] |
| blue grama-needle-and-thread grass-western wheatgrass | Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii | <35 [109,126,167] |
| blue grama-buffalo grass | Bouteloua gracilis-Buchloe dactyloides | <35 [109,167] |
| grama-galleta steppe | Bouteloua gracilis-Pleuraphis jamesii | <35 to <100 |
| blue grama-tobosa prairie | Bouteloua gracilis-Pleuraphis mutica | <35 to <100 |
| juniper-oak savanna | Juniperus ashei-Quercus virginiana | <35 |
| Ashe juniper | Juniperus ashei | <35 |
| western juniper | Juniperus occidentalis | 20-70 |
| Rocky Mountain juniper | Juniperus scopulorum | <35 [109] |
| cedar glades | Juniperus virginiana | 3-22 [59,109] |
| wheatgrass plains grasslands | Pascopyrum smithii | <5-47+ [109,118,167] |
| pinyon-juniper | Pinus-Juniperus spp. | <35 [109] |
| Colorado pinyon | Pinus edulis | 10-400+ [50,56,72,109] |
| interior ponderosa pine* | Pinus ponderosa var. scopulorum | 2-30 [7,10,84] |
| galleta-threeawn shrubsteppe | Pleuraphis jamesii-Aristida purpurea | <35 to <100 [109] |
| mesquite | Prosopis glandulosa | <35 to <100 [97,109] |
| mesquite-buffalo grass | Prosopis glandulosa-Buchloe dactyloides | <35 |
| Texas savanna | Prosopis glandulosa var. glandulosa | <10 [109] |
| mountain grasslands | Pseudoroegneria spicata | 3-40 (µ=10) [6,7] |
| oak-juniper woodland (Southwest) | Quercus-Juniperus spp. | <35 to <200 [109] |
| oak savanna | Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium | 2-14 [109,157] |
| shinnery | Quercus mohriana | <35 [109] |
| live oak | Quercus virginiana | 10 to<100 |
| little bluestem-grama prairie | Schizachyrium scoparium-Bouteloua spp. | <35 [109] |
Soapweed yucca seeds gathered from the Texas-Oklahoma border were exposed to heat treatments in a laboratory setting. Results indicate that soapweed yucca seeds are susceptible to heat and may not provide a viable regeneration source if exposed to temperatures over 250 ºF (120 ºC) [73].
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:Soapweed yucca seeds exposed to various temperatures in a convection oven indicate a reduced ability to germinate from seed exposed to high-temperature fire [73]:
|
Control |
2 hours of heat |
5 minutes of heat | |||||
| Temperature | Room temperature | 180 ºF (80 ºC) | 190 ºF (90 ºC) | 190 ºF (90 ºC) | 210 ºF (100 ºC) | 230 ºF (110 ºC) | 250 ºF (120 ºC) |
| Germination (%) | 79 | 57 | 42 | 41 | 59 | 28 | 3 |
Soapweed yucca was monitored after spring, mid-summer, and fall fires on hilltops, north-facing, and south-facing slopes in the Nebraska sandhills prairie to determine its response to fire. Prefire canopy cover was measured in 1984 and postfire cover was measured each of the 4 years following the prescribed burns, which took place on 1-2 May, 19 July, and 1 October [22]:
| Topographic Location | Treatment |
Mean Canopy Cover ± 1 s x, by year |
||||
| 1984 | 1985 | 1986 | 1987 | 1988 | ||
| Hilltop | Spring | 1 ± 1.2 | 1 ± 0.5 | 1 ± 0.5 | 1 ± 0.5 | 1 ± 0.5 |
| Summer | 4 ± 1.8 | 3 ± 2.1 | 3 ± 2.2 | 2 ± 1.4 | 1 ± 1.2 | |
| Fall | 5 ± 2.5 | -- | 1 ± 0.5 | 1 ± 0.5 | 1 ± 0.7 | |
| Unburned | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| North-facing Slope | Spring | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Summer | 2 ± 2.1 | 2 ± 1.3 | 1 ± 0.7 | 1 ± 0.7 | 2 ± 1.3 | |
| Fall | 1 ± 0.7 | -- | 1 ± 0.5 | 1 ± 0.5 | 0.0 | |
| Unburned | 3 ± 1.8 | 3 ± 1.8 | 2 ± 0.8 | 3 ± 1.8 | 2 ± 0.8 | |
| South-facing Slope | Spring | 3 ± 2.8 | 2 ± 2.1 | 3 ± 2.8 | 3 ± 2.8 | 3 ± 2.1 |
| Summer | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Fall | 4 ± 1.8 | -- | tr. | 1 ± 0.5 | 2 ± 1.3 | |
| Unburned | 2 ± 1.3 | 2 ± 1.4 | 2 ± 1.4 | 2 ± 1.4 | 1 ± 0.7 | |
Mule deer consume soapweed yucca throughout the year [80] with heaviest use in spring [35]. Rumen samples in prairie habitat indicate consumption in summer, winter, and spring months [42]. In New Mexico, soapweed yucca makes up 0% to 3% of mule deer diets [88], accounting for 0.5% of their overall diet [103]. Bighorn sheep consume soapweed yucca in North Dakota [47] and the Colorado Rockies, where soapweed yucca constitutes an average of 5.3% of their diet [148]. Soapweed yucca is also utilized by mule deer in South Dakota [168], white-tailed deer in Montana [4], pronghorn [117,142], and bison [110].
Soapweed yucca provides food, shade, and nesting sites for birds and small mammals [143]. Seeds are an important food source to small mammals [137], and leaves are consumed during times of drought and snow [122,142]. Black-tailed jackrabbits in Colorado and Kansas and white-tailed jackrabbits in Colorado utilize soapweed yucca as a food source [41]. Soapweed yucca is used by the southern plains woodrat as construction material for houses built to shelter nests and store food [145]. It is found in areas that support cotton rat populations in New Mexico [104].
Palatability/nutritional value: A plant composition analysis was conducted on soapweed yucca in South Dakota. Moisture content throughout the year varied with 4 samples, from 55.7%-64.7%. Carotene had ranges of 18.0-43.5 mg/g, ash ranged from 1.5%-1.9%, crude fat from 0.73%-1.3%, crude protein from 3.6%-4.8%, and crude fiber from 14.6%-16.0% [53]. The average percentage of crude fiber, ash, and protein as measured in leaves from soapweed yucca plants in New Mexico was 42.3%, 4.86%, and 5.57%, respectively [19].
The nutritional value (%) of soapweed yucca in the Black Hills of South Dakota was as follows [53]:
| Moisture | Carotene | Ash | Crude fat | Crude protein | Crude fiber | N-free extract | Ca | P | Fe | Mn | |
| 18 January | 60.10 | 27.60 | 1.59 | 1.13 | 4.78 | 14.81 | 17.59 | 0.33 | 0.100 | 40.76 | 23.20 |
| 16 May | 55.68 | 22.10 | 1.57 | 1.28 | 3.79 | 15.97 | 21.53 | 0.43 | 0.070 | 67.31 | 16.54 |
| 27 June | 64.71 | 18.04 | 1.87 | 0.73 | 3.93 | 14.62 | 14.14 | 0.31 | 0.117 | 32.82 | 7.84 |
| 22 October | 61.42 | 43.48 | 1.49 | 1.24 | 3.56 | 14.67 | 17.62 | 0.28 | 0.077 | 47.11 | 13.34 |
The chemical composition (%) of soapweed yucca from 3 sites in North Dakota was as follows [47]:
| January | February | March | April | May | June | July | August | September | October | November | December | |
|
Plateau |
||||||||||||
| Ca | 0.79 | 1.33 | 0.96 | 1.00 | 1.14 | 1.17 | 0.99 | 1.10 | 1.09 | 1.18 | 0.66 | 1.18 |
| Mg | 0.43 | 0.42 | 0.36 | 0.52 | 0.57 | 0.77 | 0.62 | 0.69 | 0.78 | 0.53 | 0.60 | 0.69 |
| K | 0.96 | 0.56 | 1.08 | 0.67 | 0.65 | 1.12 | 1.23 | 1.22 | 0.94 | 0.84 | 0.74 | 0.59 |
|
Flat Top Ridge |
||||||||||||
| Ca | 1.56 | 2.12 | 1.90 | 1.18 | 1.45 | 1.66 | 1.11 | 1.18 | 1.18 | 1.39 | 1.31 | 1.24 |
| Mg | 0.32 | 0.23 | 0.33 | 0.47 | 0.26 | 0.38 | 0.35 | 0.48 | 0.43 | 0.46 | 0.40 | 0.67 |
| K | 0.39 | 0.37 | 0.44 | 0.55 | 0.61 | 1.23 | 1.63 | 1.04 | 0.94 | 0.77 | 0.68 | 0.57 |
|
Side hill |
||||||||||||
| Ca | 1.13 | 1.20 | 1.40 | 1.10 | 0.87 | 1.75 | 0.80 | 1.25 | 1.38 | 0.82 | 1.05 | 1.24 |
| Mg | 0.23 | 0.19 | 0.35 | 0.42 | 0.33 | 0.58 | 0.51 | 0.47 | 0.49 | 0.77 | 0.45 | 0.60 |
| K | 0.50 | 0.48 | 0.42 | 0.59 | 0.80 | 1.26 | 0.99 | 1.04 | 0.80 | 0.93 | 0.60 | 0.42 |
A study conducted in eastern Colorado to determine the effect of geologic refuges on the occurrence of species found that areas inaccessible to cattle supported 1.96% soapweed yucca cover as opposed to 1.45% in browsed areas. Soapweed yucca was listed as having relatively low palatability with the potential to become more palatable at different times in the season [100].
Cover value: Dittberner and Olson [37] report the cover value of soapweed yucca for wildlife species as follows:
| MT | ND | WY | |
| Pronghorn | poor | fair | |
| Elk | poor | ||
| Mule deer | poor | fair | poor |
| White-tailed deer | poor | ||
| Small mammals | fair | poor | |
| Small nongame birds | fair | poor | |
| Upland game birds | poor | poor | |
| Waterfowl | poor |
Birds, small mammals, and reptiles utilize soapweed yucca for shade and nesting sites [137]. Scaled quail in Texas utilize it for night roosting [141] and sharp-tailed grouse broods use it for cover [58]
VALUE FOR REHABILITATION OF DISTURBED SITES:Soapweed yucca seeds obtained from mid-October through early spring were used for reclamation in southeastern Montana. Seeds were harvested from dehiscent capsules while they were still intact or after being dried. Best results were obtained from seed stored at 40 ºF (4 ºC) over winter and planted in spring and seed planted immediately after being collected in the fall [43]. On previously mined land in southeastern Montana, reseeding occurred with either 4-species or 16-species mixtures to determine rates of perennial plant regeneration under various treatments. Soapweed yucca returned to plots seeded with the 4-species mixture at a density of 0.3 plant/m² 5 years after seeding, and did not return on plots seeded with the 16-species mixture. For additional information on methods utilized in this project see [67].
Of 28 soapweed yucca plants planted in 1988 on a prairie reconstruction site in Kansas, 79% survived the 1st year and 64% survived the 2nd year. None of the plants flowered within that 2-year period. Of 19 plants planted in 1985, 100% survived the 1st year. No record was made beyond 1986 [115].
Viable soapweed yucca seeds are black. Seeds with a white seed coat lack an endosperm and are not viable [1].
OTHER USES:Eradication of soapweed yucca from rangelands in favor of more palatable species has been achieved through various methods. One study found repeated aerial applications of the herbicide silvex controlled soapweed yucca [20], while another achieved control through the burning or cutting of plant tops in combination with the use of tebuthiuron, picloram, and 2,4,5-T [93] (2,4,5-T is now banned by the E.P.A. [152]). Grazing forage was increased by 37% and soil water content significantly reduced (P=0.05) on a site where chemical control of soapweed yucca was achieved [136].
Soapweed yucca populations increased significantly (P<0.05) after aboveground portions were crushed by off-road vehicles, and the plants sprouted from belowground portions [131]. Fluoride and sulfur from coal-fired plant emissions could have adverse effects on soapweed yucca, but damage to plants would likely not be detected prior to overstory effects such as reduced needle length and tissue necrosis [55].
When inoculated with mycorrhizae in a laboratory setting, the mean dry mass of inoculated soapweed yucca plants was 87% greater than nonmycorrhizal control plants [166].1. Addicott, John F. 1986. Variation in the costs and benefits of mutualism: the interaction between yuccas and yucca moths. Oecologia. 70: 486-494. [8880]
2. Albertson, F. W. 1937. Ecology of mixed prairie in west central Kansas. Ecological Monographs. 7: 483-547. [5057]
3. Alexander, Robert R.; Pond, Floyd W.; Rodgers, Jane E. [In press]. Yucca L.--yucca. In: Bonner, Franklin T.; Nisley, Rebecca G.; Karrfait, R. P., coords tech. coord. Woody plant seed manual. Agric. Handbook 727. Washington, DC: U.S. Department of Agriculture, Forest Service (Producer). Available:http://www.nsl.fs.usda.gov/wpsm/Yucca.pdf [2005, December 12]. [55550]
4. Allen, Eugene O. 1968. Range use, foods, condition, and productivity of white-tailed deer in Montana. Journal of Wildlife Management. 32(1): 130-141. [16331]
5. Arno, Stephen F. 1979. Forest regions of Montana. Res. Pap. INT-218. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 39 p. [340]
6. Arno, Stephen F. 1980. Forest fire history in the Northern Rockies. Journal of Forestry. 78(8): 460-465. [11990]
7. Arno, Stephen F. 2000. Fire in western forest ecosystems. In: Brown, James K.; Smith, Jane Kapler, eds. Wildland fire in ecosystems: Effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 97-120. [36984]
8. Arno, Stephen F.; Gruell, George E. 1983. Fire history at the forest-grassland ecotone in southwestern Montana. Journal of Range Management. 36(3): 332-336. [342]
9. Ault, Stacey C.; Stormer, Fred A. 1983. Seasonal food selection by scaled quail in northwest Texas. Journal of Wildlife Management. 47(1): 222-228. [12168]
10. Baisan, Christopher H.; Swetnam, Thomas W. 1990. Fire history on a desert mountain range: Rincon Mountain Wilderness, Arizona, U.S.A. Canadian Journal of Forest Research. 20: 1559-1569. [14986]
11. Bare, Janet E. 1979. Wildflowers and weeds of Kansas. Lawrence, KS: The Regents Press of Kansas. 509 p. [3801]
12. Barnes, P. W.; Harrison A. T. 1982. Species distribution and community organization in a Nebraska sandhills mixed prairie as influenced by plant/soil-water relationships. Oecologia. 52: 192-201. [5026]
13. Barnes, P. W.; Harrison, A. T.; Heinisch, S. P. 1984. Vegetation patterns in relation to topography and edaphic variation in Nebraska Sandhills prairie. Prairie Naturalist. 16(4): 145-157. [396]
14. Beatley, Janice C. 1966. Ecological status of introduced brome grasses (Bromus spp.) in desert vegetation of southern Nevada. Ecology. 47(4): 548-554. [409]
15. Bell, Willis H.; Castetter, Edward F. 1941. Ethnobiological studies in the American Southwest. IV. The utilization of yucca, sotol, and beargrass by the aborigines in the American Southwest. University of New Mexico Bulletin. 5(5): 1-74. [38174]
16. Bentz, S. E.; Talbott, H.-J. 1992. Micropropagation of yucca (Yucca glauca Nutt.). In: Bajaj, Y. P. S., ed. High-tech and micropropagation III. Biotechnology in Agriculture and Forestry: Volume 19. Berlin: Springer-Verlag: 330-337. [55524]
17. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434]
18. Botkin, C. W.; Shires, L. B. 1944. Tensile strength of yucca fibers. Technical Bulletin 316. Las Cruces, NM: New Mexico State University, Agricultural Experiment Station. 30 p. [4527]
19. Botkin, C. W.; Shires, L. B.; Smith, E. C. 1943. Fiber of native plants in New Mexico. Bulletin 300. Las Cruces, NM: New Mexico State University, Agricultural Experiment Station. 38 p. [5097]
20. Bovey, R. W. 1964. Control of yucca by aerial application of herbicides. Journal of Range Management. 17(4): 194-196. [55526]
21. Bragg, Thomas B. 1978. Effects of burning, cattle grazing, and topography on vegetation of the choppy sands range site in the Nebraska sandhills prairie. In: Hyder, Donald N., ed. Proceedings, 1st international rangeland congress; 1978 August 14-18; Denver, CO. Denver, CO: Society for Range Management: 248-253. [4468]
22. Bragg, Thomas B. 1998. Fire in the Nebraska sandhills prairie. In: Pruden, Teresa L.; Brennan, Leonard A., eds. Fire in ecosystem management: shifting the paradigm from suppression to prescription: Proceedings, Tall Timbers fire ecology conference; 1996 May 7-10; Boise, ID. No. 20. Tallahassee, FL: Tall Timbers Research Station: 179-194. [35628]
23. Brown, David E. 1982. Great Basin conifer woodland. In: Brown, David E., ed. Biotic communities of the American Southwest--United States and Mexico. Desert Plants. 4(1-4): 52-57. [535]
24. Brown, David E. 1982. Plains and Great Basin grasslands. In: Brown, David E., ed. Biotic communities of the American Southwest--United States and Mexico. Desert Plants. 4(1-4): 115-121. [536]
25. Brown, Raymond William, Jr. 1965. The distribution of plant communities in the badlands of southeastern Montana. Bozeman, MT: Montana State University. 145 p. Thesis. [46903]
26. Burkhardt, Wayne J.; Tisdale, E. W. 1976. Causes of juniper invasion in southwestern Idaho. Ecology. 57: 472-484. [565]
27. Burzlaff, Donald F. 1962. A soil and vegetation inventory and analysis of three Nebraska Sandhills range sites. Research Bulletin 206. Lincoln, NE: University of Nebraska College of Agriculture, Agricultural Experiment Station. 33 p. [21600]
28. Cable, Dwight R. 1965. Damage to mesquite, Lehmann lovegrass, and black grama by a hot June fire. Journal of Range Management. 18: 326-329. [18587]
29. Castetter, Edward F. 1935. Ethnobiological studies in the American Southwest. Biological Series No. 4: Volume 1. Albuquerque, NM: University of New Mexico. 62 p. [35938]
30. Castetter, Edward F.; Opler, M. E. 1936. Ethnobiological studies in the American Southwest. III. The ethnobiology of the Chiricahua and Mescalero Apache. University of New Mexico Bulletin. 4(5): 1-63. [38173]
31. Costello, David F. 1944. Important species of the major forage types in Colorado and Wyoming. Ecological Monographs. 14(1): 107-134. [693]
32. Daley, Richard Halbert. 1972. The native sand sage vegetation of eastern Colorado. Fort Collins, CO: Colorado State University. 62 p. Thesis. [4905]
33. Davis, Charles A.; Medlin, Joel A.; Griffing, James P. 1975. Abundance of black-tailed jackrabbits, desert cottontail rabbits, and coyotes in southeastern New Mexico. Research Report 293. Las Cruces, NM: New Mexico State University, Agricultural Experiment Station. 8 p. [25081]
34. Despain, Don G. 1973. Vegetation of the Big Horn Mountains, Wyoming, in relation to substrate and climate. Ecological Monographs. 43(3): 329-355. [789]
35. Dietz, Donald R.; Nagy, Julius G. 1976. Mule deer nutrition and plant utilization. In: Workman, Gar W.; Low, Jessop B., eds. Mule deer decline in the West: A symposium; [Date of conference unknown]; [Location unknown]. Logan, UT: Utah State University, College of Natural Resources, Utah Agriculture Experiment Station: 71-78. [6909]
36. Dingman, Sandra; Paintner, Kara J. 2001. Defining landscape vision to monitor and manage prescribed fire at Badlands National Park, South Dakota. In: Bernstein, Neil P.; Ostrander, Laura J., eds. Seeds for the future; roots of the past: Proceedings of the 17th North American prairie conference; 2000 July 16-20; Mason City, IA. Mason City, IA: North Iowa Area Community College: 73-78. [46496]
37. Dittberner, Phillip L.; Olson, Michael R. 1983. The plant information network (PIN) data base: Colorado, Montana, North Dakota, Utah, and Wyoming. FWS/OBS-83/86. Washington, DC: U.S. Department of the Interior, Fish and Wildlife Service. 786 p. [806]
38. Dodd, Rhea Jean; Linhart, Yan B. 1994. Reproductive consequences of interactions between Yucca glauca (Agavaceae) and Tegeticula yuccasella (Lepidoptera) in Colorado. American Journal of Botany. 81(7): 815-825. [55531]
39. Dorn, Robert D. 1977. Flora of the Black Hills. Cheyenne, WY: Robert D. Dorn and Jane L. Dorn. 377 p. [820]
40. Dorn, Robert D. 1984. Vascular plants of Montana. Cheyenne, WY: Mountain West Publishing. 276 p. [819]
41. Dunn, John P.; Chapman, Joseph A.; Marsh, Rex E. 1982. Jackrabbits: Lepus californicus and allies. In: Chapman, J. A.; Feldhamer, G. A., eds. Wild mammals of North America: biology, management and economics. Baltimore, MD: The John Hopkins University Press: 124-145. [25016]
42. Dusek, Gary L. 1975. Range relations of mule deer and cattle in prairie habitat. Journal of Wildlife Management. 39(3): 605-616. [5938]
43. Eddleman, Lee E. 1977. Indigenous plants of southeastern Montana. I. Viability and suitability for reclamation in the Fort Union Basin. Special Publication 4. Missoula, MT: University of Montana, School of Forestry, Montana Forest and Conservation Experiment Station. 122 p. [42440]
44. Emerson, Fred W. 1932. The tension zone between the grama grass and pinyon-juniper associations in northeastern New Mexico. Ecology. 13: 247-258. [3362]
45. Eversman, Sharon. 1982. Epiphytic lichens of a ponderosa pine forest in southeastern Montana. Bryologist. 85(2): 204-213. [15780]
46. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905]
47. Fairaizl, Steven D. 1978. Bighorn sheep in North Dakota: population estimates, food habits and their biogeochemistry. Grand Forks, ND: University of North Dakota. 83 p. Thesis. [Project No.: W-67-R-17. Bismark, ND: North Dakota State Game and Fish Department. 51 p. + appendices]. [25841]
48. Fisser, Herbert G.; Johnson, Kendall L.; Moore, Kellie S.; Plumb, Glenn E. 1989. 51-year change in the shortgrass prairie of eastern Wyoming. In: Bragg, Thomas B.; Stubbendieck, James, eds. Prairie pioneers: ecology, history and culture: Proceedings, 11th North American prairie conference; 1988 August 7-11; Lincoln, NE. Lincoln, NE: University of Nebraska: 29-31. [14015]
49. Flora of North America Association. 2007. Flora of North America: The flora, [Online]. Flora of North America Association (Producer). Available: http://www.fna.org/FNA [2007, February 22]. [36990]
50. Floyd, M. Lisa; Romme, William H.; Hanna, David D. 2000. Fire history and vegetation pattern in Mesa Verde National Park, Colorado, USA. Ecological Applications. 10(6): 1666-1680. [37590]
51. Frolik, A. L.; Shepherd, W. O. 1940. Vegetative composition and grazing capacity of a typical area of Nebraska sandhill range land. Research Bulletin No. 117. Lincoln, NE: University of Nebraska Agricultural Experimental Station. 39 p. [5417]
52. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; Lewis, Mont E.; Smith, Dixie R. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [998]
53. Gastler, George F.; Moxon, Alvin L.; McKean, William T. 1951. Composition of some plants eaten by deer in the Black Hills of South Dakota. Journal of Wildlife Management. 15(4): 352-357. [3996]
54. Gese, Eric M.; Rongstad, Orrin J.; Mytton, William R. 1988. Home range and habitat use of coyotes in southeastern Colorado. Journal of Wildlife Management. 52(4): 640-646. [6136]
55. Gordon, C. C.; Tourangeau, P. C.; Rice, P. M. 1978. Investigation of the impact of coal-fired power plant emissions upon the disease/health/growth characteristics of ponderosa pine - skunkbush ecosystems and grassland ecosystems in southeastern Montana. In: Preston, Eric M.; Lewis, Robert A., eds. The bioenvironmental impact of a coal-fired power plant: 3rd interim report. Ecological Research Series: EPA-600/3-78-021. Corvallis, OR: U.S. Environmental Protection Agency, Office of Research and Development, Corvallis Environmental Research Laboratory: 65-139. [47317]
56. Gottfried, Gerald J.; Swetnam, Thomas W.; Allen, Craig D.; Betancourt, Julio L.; Chung-MacCoubrey, Alice L. 1995. Pinyon-juniper woodlands. In: Finch, Deborah M.; Tainter, Joseph A., eds. Ecology, diversity, and sustainability of the Middle Rio Grande Basin. Gen. Tech. Rep. RM-GTR-268. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 95-132. [26188]
57. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603]
58. Grosz, Kevin Lee. 1988. Sharp-tailed grouse nesting and brood rearing habitat in grazed and nongrazed treatments in south-central North Dakota. Fargo, ND: North Dakota State University. 72 p. Thesis. [5491]
59. Guyette, Richard; McGinnes, E. A., Jr. 1982. Fire history of an Ozark glade in Missouri. Transactions, Missouri Academy of Science. 16: 85-93. [5170]
60. Harrell, Wade C.; Fuhlendorf, Samuel D.; Bidwell, Terrence G. 2001. Effects of prescribed fire on sand shinnery oak communities. Journal of Range Management. 54(6): 685-690. [40162]
61. Harrington, H. D. 1964. Manual of the plants of Colorado. 2nd ed. Chicago: The Swallow Press, Inc. 666 p. [6851]
62. Hart, Jeffrey A. 1981. The ethnobotany of the Northern Cheyenne Indians of Montana. Journal of Ethnopharmacology. 4: 1-55. [35893]
63. Heyerdahl, Emily K.; Berry, Dawn; Agee, James K. 1994. Fire history database of the western United States. Final report. Interagency agreement: U.S. Environmental Protection Agency DW12934530; U.S. Department of Agriculture, Forest Service PNW-93-0300; University of Washington 61-2239. Seattle, WA: U.S. Department of Agriculture, Pacific Northwest Research Station; University of Washington, College of Forest Resources. 28 p. [+ appendices]. Unpublished report on file with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. [27979]
64. Higgins, Kenneth F.; Kruse, Arnold D.; Piehl, James L. 1989. Effects of fire in the Northern Great Plains. Ext. Circ. EC-761. Brookings, SD: South Dakota State University, Cooperative Extension Service; South Dakota Cooperative Fish and Wildlife Research Unit. 47 p. [14749]
65. Hirsch, Kathie Jean. 1985. Habitat classification of grasslands and shrublands of southwestern North Dakota. Fargo, ND: North Dakota State University. 281 p. Dissertation. [40326]
66. Hoffman, G. R.; Timken, R. L. 1970. Ecologic observations on Pinus ponderosa laws. (Pinaceae) at its eastern most extension in South Dakota. The Southwestern Naturalist. 14(3): 327-336. [11502]
67. Holechek, Jerry L.; Depuit, Edward J.; Coenenberg, Joe G.; Valdez, Raul. 1981. Fertilizer effects on establishment of two seed mixtures on mined land in southeastern Montana. Journal of Soil and Water Conservation. August: 241-244. [35020]
68. Humphrey, Robert R. 1974. Fire in the deserts and desert grassland of North America. In: Kozlowski, T. T.; Ahlgren, C. E., eds. Fire and ecosystems. New York: Academic Press: 365-400. [14064]
69. Iffrig, Greg F. 1983. Distribution and ecology of loess hill prairies in Atchison and Holt Counties in northwest Missouri. In: Kucera, Clair L., ed. Proceedings, 7th North American prairie conference; 1980 August 4-6; Springfield, MO. Columbia, MO: University of Missouri: 129-133. [3214]
70. Kartesz, John T.; Meacham, Christopher A. 1999. Synthesis of the North American flora (Windows Version 1.0), [CD-ROM]. In: North Carolina Botanical Garden (Producer). In cooperation with: The Nature Conservancy, Natural Resources Conservation Service, and U.S. Fish and Wildlife Service. [36715]
71. Kaul, Robert P.; Keeler, Kathleen H. 1980. Effects of grazing and juniper canopy closure on the prairie flora in Nebraska high-plains canyons. In: Kucera, Clair L., ed. Proceedings, 7th North American prairie conference; 1980 August 4-6; Springfield, MO. Columbia, MO: University of Missouri: 95-105. [2923]
72. Keeley, Jon E. 1981. Reproductive cycles and fire regimes. In: Mooney, H. A.; Bonnicksen, T. M.; Christensen, N. L.; Lotan, J. E.; Reiners, W. A., tech. coords. Fire regimes and ecosystem properties: Proceedings of the conference; 1978 December 11-15; Honolulu, HI. Gen. Tech. Rep. WO-26. Washington, DC: U.S. Department of Agriculture, Forest Service: 231-277. [4395]
73. Keeley, Jon E.; Meyers, Adriene. 1985. Effect of heat on seed germination of southwestern Yucca species. The Southwestern Naturalist. 30(2): 303-304. [5761]
74. Kieft, Thomas L. 1994. Grazing and plant-canopy effects on semiarid soil microbial biomass and respiration. Biology and Fertility of Soils. 18(2): 155-162. [55543]
75. Kindscher, Kelly. 1988. The ethnobotanical use of native prairie plants as food. In: Davis, Arnold; Stanford, Geoffrey, eds. The prairie: roots of our culture; foundation of our economy: Proceedings, 10th North American prairie conference; 1986 June 22-26; Denton, TX. Dallas, TX: Native Prairie Association of Texas: 02.04: 1-3. [25585]
76. Kingsolver, R. W. 1986. Vegetative reproduction as a stabilizing feature of the population dynamics of Yucca glauca. Oecologia. 69: 380-387. [4504]
77. Kinraide, Thomas B. 1978. The ecological distribution of cholla cactus (Opuntia imbricata (Haw.) DC.) in El Paso County, Colorado. The Southwestern Naturalist. 23(1): 117-134. [5163]
78. Kucera, Clair L. 1981. Grasslands and fire. In: Mooney, H. A.; Bonnicksen, T. M.; Christensen, N. L.; Lotan, J. E.; Reiners, W. A., tech. coords. Fire regimes and ecosystem properties: Proceedings of the conference; 1978 December 11-15; Honolulu, HI. Gen. Tech. Rep. WO-26. Washington, DC: U.S. Department of Agriculture, Forest Service: 90-111. [4389]
79. Kuchler, A. W. 1964. United States [Potential natural vegetation of the conterminous United States]. Special Publication No. 36. New York: American Geographical Society. 1:3,168,000; colored. [3455]
80. Kufeld, Roland C.; Wallmo, O. C.; Feddema, Charles. 1973. Foods of the Rocky Mountain mule deer. Res. Pap. RM-111. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 31 p. [1387]
81. Lacey, John; Mosley, John. 2002. 250 plants for range contests in Montana. MONTGUIDE MT198402 AG 6/2002. Range E-2 (Misc.). Bozeman, MT: Montana State University, Extension Service. 4 p. [43671]
82. Landis, Thomas D.; Simonich, Edward J. 1984. Producing native plants as container seedlings. In: Murphy, Patrick M., comp. The challenge of producing native plants for the Intermountain area: Proceedings: Intermountain Nurseryman's Association 1983 conference; 1983 August 8-11; Las Vegas, NV. Gen. Tech. Rep. INT-168. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: 16-25. [49420]
83. Lauver, Chris L.; Kindscher, Kelly; Faber-Langendoen, Don; Schneider, Rick. 1999. A classification of the natural vegetation of Kansas. The Southwestern Naturalist. 44(4): 421-443. [38847]
84. Laven, R. D.; Omi, P. N.; Wyant, J. G.; Pinkerton, A. S. 1980. Interpretation of fire scar data from a ponderosa pine ecosystem in the central Rocky Mountains, Colorado. In: Stokes, Marvin A.; Dieterich, John H., tech. coords. Proceedings of the fire history workshop; 1980 October 20-24; Tucson, AZ. Gen. Tech. Rep. RM-81. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 46-49. [7183]
85. Lewis, James K.; Van Dyne, George M.; Albee, Leslie R.; Whetzal, Frank W. 1956. Intensity of grazing: Its effect on livestock and forage production. Bulletin 459. Brookings, SD: South Dakota State College, Agricultural Experiment Station. 44 p. [11737]
86. Loftin, Samuel R.; Chung-MacCoubrey, Alice L.; Robbie, Wayne A. 1995. Desert grassland and shrubland ecosystems. In: Finch, Deborah M.; Tainter, Joseph A., eds. Ecology, diversity, and sustainability of the Middle Rio Grande Basin. Gen. Tech. Rep. RM-GTR-268. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 81-94. [26187]
87. Looman, J. 1980. The vegetation of the Canadian prairie provinces. II. The grasslands: Part 1. Phytocoenologia. 8(2): 153-190. [18400]
88. Mahgoub, El Fatih; Pieper, Rex D.; Holechek, Jerry L.; Wright, Jimmie D.; Howard, V. W., Jr. 1987. Botanical content of mule deer diets in south-central New Mexico. New Mexico Journal of Science. 27(1): 21-27. [3259]
89. Maragni, Laura A.; Knapp, Alan K.; McAllister, Christine A. 2000. Patterns and determinants of potential carbon gain in the C3 evergreen Yucca glauca (Liliaceae) in a C4 grassland. American Journal of Botany. 87(2): 230-236. [36399]
90. Marr, John W. 1961. Ecosystems of the east slope of the Front Range in Colorado. Studies Series in Biology 8. Boulder, CO: University of Colorado. 134 p. [5724]
91. Martin, William C.; Hutchins, Charles R. 1981. A flora of New Mexico. Volume 2. Germany: J. Cramer. 2589 p. [37176]
92. Mast, Joy Nystrom; Veblen, Thomas T.; Hodgson, Michael E. 1997. Tree invasion within a pine/grassland ecotone: an approach with historic aerial photography and GIS modeling. Forest Ecology and Management. 93: 181-194. [27729]
93. Masters, Robert A.; Marietta, Kay L.; Britton, Carlton M. 1988. Response of yucca to fire, herbicide, and mechanical treatments. Texas Journal of Agriculture and Natural Resources. 2: 4-6. [11801]
94. McArthur, E. Durant; Sanderson, Stewart C. 1991. Great Sand Dunes National Monument vegetation patterns. In: Plumb, Glenn E., ed. University of Wyoming: National Park Service Research Center 15th annual report 1991. Laramie, WY: University of Wyoming: 185-189. [29955]
95. McGinnies, William G. 1972. North America. In: McKell, Cyrus M.; Blaisdell, James P.; Goodin, Joe R., tech. eds. Wildland shrubs--their biology and utilization: An international symposium: Proceedings; 1971 July; Logan, UT. Gen. Tech. Rep. INT-1. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: 55-66. [22750]
96. McGinnies, William J.; Shantz, Homer L.; McGinnies, William G. 1991. Changes in vegetation and land use in eastern Colorado: A photographic study, 1904-1986. ARS-85. Washington, DC: U.S. Department of Agriculture, Agricultural Research Service. 165 p. [18825]
97. McPherson, Guy R. 1995. The role of fire in the desert grasslands. In: McClaran, Mitchel P.; Van Devender, Thomas R., eds. The desert grassland. Tucson, AZ: The University of Arizona Press: 130-151. [26576]
98. McPherson, Guy R.; Wright, Henry A. 1989. Direct effects of competition on individual juniper plants: a field study. Journal of Applied Ecology. 26(3): 979-988. [13032]
99. McPherson, Guy R.; Wright, Henry A.; Wester, David B. 1988. Patterns of shrub invasion in semiarid Texas grasslands. The American Midland Naturalist. 120(2): 391-397. [7197]
100. Milchunas, Daniel G.; Noy-Meir, Imanuel. 2004. Geologic grazing refuges and grassland diversity: a shortgrass steppe study. Journal of Range Management. 57(2): 141-147. [48529]
101. Miller, Richard F.; Rose, Jeffery A. 1995. Historic expansion of Juniperus occidentalis (western juniper) in southeastern Oregon. The Great Basin Naturalist. 55(1): 37-45. [25666]
102. Missouri Department of Conservation. 2005. Missouri species and communities of conservation concern, [Online]. In: Endangered species. Columbia, MO: Missouri Department of Conservation (Producer). Available: http://www.mdc.mo.gov/documents/nathis/endangered/checklist.pdf [2005, July 25]. [53847]
103. Mohgoub, Elfatih Eltagi. 1984. Seasonal food habits of mule deer in the foothills of the Sacramento Mountains, New Mexico. Las Cruces, NM: New Mexico State University. 89 p. Dissertation. [47328]
104. Mohlhenrich, John S. 1961. Distribution and ecology of of the hispid and least cotton rats in New Mexico. Journal of Mammalogy. 42(1): 13-24. [25672]
105. Moir, William H. 1969. Steppe communities in the foothills of the Colorado Front Range and their relative productivities. The American Midland Naturalist. 81(2): 331-340. [11152]
106. Moravec, Denise L. 1994. Flowering phenology and fruit reproductive success of Yucca glauca Nuttall in western Nebraska. Lincoln, NE: University of Nebraska. 128 p. Thesis. [55548]
107. Morris, Melvin S.; Schmautz, Jack E.; Stickney, Peter F. 1962. Winter field key to the native shrubs of Montana. Bulletin No. 23. Missoula, MT: Montana State University, Montana Forest and Conservation Experiment Station. 70 p. [17063]
108. Novacek, Jean M. 1989. The water and wetland resources of the Nebraska sandhills. In: Vander Valk, Arnold, ed. Northern prairie wetlands. Ames, IA: Iowa State University Press: 340-384. [15221]
109. Paysen, Timothy E.; Ansley, R. James; Brown, James K.; Gottfried, Gerald J.; Haase, Sally M.; Harrington, Michael G.; Narog, Marcia G.; Sackett, Stephen S.; Wilson, Ruth C. 2000. Fire in western shrubland, woodland, and grassland ecosystems. In: Brown, James K.; Smith, Jane Kapler, eds. Wildland fire in ecosystems: Effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 121-159. [36978]
110. Peden, Donald G. 1976. Botanical composition of bison diets on shortgrass plains. The American Midland Naturalist. 96(1): 225-229. [24596]
111. Perry, Jennifer C.; Mondor, Edward B.; Addicott, John F. 2004. An indirect mutualism: ants deter seed predators from ovipositing in yucca fruit. Canadian Journal of Zoology. 82: 823-827. [55532]
112. Peters, Erin F.; Bunting, Stephen C. 1994. Fire conditions pre- and postoccurrence of annual grasses on the Snake River Plain. In: Monsen, Stephen B.; Kitchen, Stanley G., comps. Proceedings--ecology and management of annual rangelands; 1992 May 18-22; Boise, ID. Gen. Tech. Rep. INT-GTR-313. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station: 31-36. [24249]
113. Pfister, James A.; Adams, Don C. 1993. Factors influencing pine needle consumption by grazing cattle during winter. Journal of Range Management. 46(5): 394-398. [22429]
114. Piper, Jon K.; Gernes, Mark C. 1989. Vegetation dynamics of three tallgrass prairie sites. In: Bragg, Thomas B.; Stubbendieck, James, eds. Prairie pioneers: ecology, history and culture: Proceedings, 11th North American prairie conference; 1988 August 7-11; Lincoln, NE. Lincoln, NE: University of Nebraska: 9-14. [14011]
115. Platt, Dwight R. 1988. Development and survival of plants in a prairie reconstruction at Kauffman Museum in south central Kansas. In: Davis, Arnold; Stanford, Geoffrey, eds. The prairie: roots of our culture; foundation of our economy: Proceedings, 10th North American prairie conference; 1986 June 22-26; Denton, TX. Dallas, TX: Native Prairie Association of Texas: 09.02: 1-5. [25603]
116. Pool, Raymond J. 1914. A study of the vegetation of the sandhills of Nebraska. In: Minnesota Botanical Studies. Botanical Series VII. Minneapolis, MN: [University of Minnesota]: 189-312. [5891]
117. Prenzlow, E. J.; Gilbert, D. L.; Glover, F. A. 1968. Some behavior patterns of the pronghorn. Special Report No. 17/GFP-R-S 17. Denver, CO: Colorado Department of Game, Fish and Parks. 16 p. [25691]
118. Quinnild, Clayton L.; Cosby, Hugh E. 1958. Relicts of climax vegetation on two mesas in western North Dakota. Ecology. 39(1): 29-32. [1925]
119. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843]
120. Reynolds, Richard T.; Linkhart, Brian D.; Jeanson, Judy-Jo. 1985. Characteristics of snags and trees containing cavities in a Colorado conifer forest. Res. Note RM-455. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 6 p. [15568]
121. Ribble, David O.; Samson, Fred B. 1987. Microhabitat associations of small mammals in southeastern Colorado, with special emphasis on Peromyscus (Rodentia). The Southwestern Naturalist. 32(3): 291-303. [15488]
122. Riegel, Andrew. 1942. Some observations of the food coactions of rabbits in western Kansas during periods of stress. Transactions, Kansas Academy of Science. 45: 369-373. [35542]
123. Robbie, Wayne A. 2004. Grassland assessment categories and extent. In: Finch, Deborah M., ed. Assessment of grassland ecosystem conditions in the southwestern United States. Gen. Tech. Rep. RMRS-GTR-135-vol. 1. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 11-17. [52284]
124. Roessler, Paul G.; Monson, Russell K. 1985. Midday depression in net photosynthesis and stomatal conductance in Yucca glauca: Relative contributions of leaf temperature and leaf-to-air water vapor concentration difference. Oecologia. 67: 380-387. [37]
125. Ross, Robert L.; Hunter, Harold E. 1976. Climax vegetation of Montana: Based on soils and climate. Bozeman, MT: U.S. Department of Agriculture, Soil Conservation Service. 64 p. [2028]
126. Rowe, J. S. 1969. Lightning fires in Saskatchewan grassland. The Canadian Field-Naturalist. 83: 317-324. [6266]
127. Sapsis, David B. 1990. Ecological effects of spring and fall prescribed burning on basin big sagebrush/Idaho fescue--bluebunch wheatgrass communities. Corvallis, OR: Oregon State University. 105 p. Thesis. [16579]
128. Schlicht, Dennis W.; Orwig, Timothy T. 1992. Sequential use of niche by prairie obligate skipper butterflies (Lepidoptera: Hesperidae) with implications for management. In: Smith, Daryl D.; Jacobs, Carol A., eds. Recapturing a vanishing heritage: Proceedings, 12th North American prairie conference; 1990 August 5-9; Cedar Falls, IA. Cedar Falls, IA: University of Northern Iowa: 137-139. [24730]
129. Shantz, H. L. 1906. A study of the vegetation of the mesa region east of Pike's Peak: the Bouteloua formation. Botanical Gazette. 42(1): 16-47. [55541]
130. Shaw, R. B.; Anderson, S. L.; Schultz, K. A.; Diersing, V. E. 1989. Floral inventory for the U. S. Army Pinon Canyon Maneuver Site, Colorado. Phytologia. 67(1): 1-42. [12137]
131. Shaw, R. B.; Diersing, V. E. 1990. Tracked vehicle impacts on vegetation at the Pinon Canyon Maneuver Site, Colorado. Journal of Environmental Quality. 19: 234-243. [24484]
132. Shiflet, Thomas N., ed. 1994. Rangeland cover types of the United States. Denver, CO: Society for Range Management. 152 p. [23362]
133. Shoop, M. C.; Clark, Richard C.; Laycock, W. A.; Hansen, Richard M. 1985. Cattle diets on shortgrass ranges with different amounts of fourwing saltbush. Journal of Range Management. 38(5): 443-449. [42455]
134. Simpson, Philip George. 1975. Anatomy and morphology of the Joshua tree (Yucca brevifolia): an arborescent monocot. Santa Barbara, CA: University of California. 524 p. Dissertation. [6280]
135. Smith, Ronald C. 1989. Yucca glauca. American Nurseryman. 170(3): 126. [55533]
136. Sosebee, R. E.; Churchill, F. M.; Green, C. W. 1982. Soil water depletion by yucca. Journal of Range Management. 35(6): 774-776. [55534]
137. Stephens, H. A. 1973. Woody plants of the North Central Plains. Lawrence, KS: The University Press of Kansas. 530 p. [3804]
138. Stickney, Peter F. 1989. FEIS postfire regeneration workshop--April 12: Seral origin of species comprising secondary plant succession in Northern Rocky Mountain forests. 10 p. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. [20090]
139. Stockrahm, Donna M. Bruns; Olson, Theresa Ebbenga; Harper, Elizabeth K. 1993. Plant species in black-tailed prairie dog towns in Billings County, North Dakota. Prairie Naturalist. 25(2): 173-183. [23167]
140. Stormer, Fred A. 1979. Summer habitat of scaled quail in the Texas panhandle. In: Sosebee, Ronald E.; Wright, Henry A.; eds. Research highlights--1979: Noxious brush and weed control; range and wildlife management. Volume 10. Lubbock, TX: Texas Tech University, College of Agricultural Sciences: 58. [39008]
141. Stormer, Fred A. 1984. Night-roosting habitat of scaled quail. Journal of Wildlife Management. 48(1): 191-197. [23083]
142. Stubbendieck, James; Coffin, Mitchell J.; Landholt, L. M. 2003. Weeds of the Great Plains. 3rd ed. Lincoln, NE: Nebraska Department of Agriculture, Bureau of Plant Industry. 605 p. In cooperation with: University of Nebraska - Lincoln. [50776]
143. Stubbendieck, James; Nichols, James T.; Butterfield, Charles H. 1989. Nebraska range and pasture forbs and shrubs (including succulent plants). Extension Circular 89-118. Lincoln, NE: University of Nebraska, Nebraska Cooperative Extension. 153 p. [10168]
144. Terwilliger, Valery J.; Betancourt, Julio L.; Leavitt, Steven W.; Van de water, Peter K. 2002. Leaf cellulose delta D and delta18 O trends with elevation differ in direction among co-occurring, semiarid plant species. Geochimica et Cosmochimica Acta. 66(22): 3887-3900. [54574]
145. Thies, Monte; Caire, William. 1990. Association of Neotoma micropus nests with various plant species in southwestern Oklahoma. The Southwestern Naturalist. 35(1): 80-102. [11140]
146. Thilenius, John F.; Brown, Gary R.; Medina, Alvin L. 1995. Vegetation on semi-arid rangelands, Cheyenne River Basin, Wyoming. Gen. Tech. Rep. RM-GTR-263. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 60 p. [26478]
147. Thom, Richard H.; Wilson, James H. 1983. The natural divisions of Missouri: an introduction to the natural history of the state. In: Kucera, Clair L., ed. Proceedings of the 7th North American prairie conference; 1980 August 4-6; Springfield, MO. Columbia, MO: University of Missouri: 1-11. [3190]
148. Todd, J. W. 1975. Foods of Rocky Mountain bighorn sheep in southern Colorado. Journal of Wildlife Management. 39(1): 108-111. [6218]
149. Tolstead, W. L. 1941. Germination habits of certain sandhills plants in Nebraska. Ecology. 22: 393-397. [5020]
150. U.S. Department of Agriculture, Natural Resources Conservation Service, Tucson Plant Materials Center. 2001. Commercial sources of conservation plant materials, [Online]. Available: http://plant-materials.nrcs.usda.gov/pubs/azpmsarseedlist0501.pdf [2003, August 25]. [44989]
151. U.S. Department of Agriculture, Natural Resources Conservation Service. 2007. PLANTS Database, [Online]. Available: https://plants.usda.gov /. [34262]
152. U.S. Environmental Protection Agency. 2004. UN PIC (Prior Informed Consent) and U.S. PIC-nominated pesticides list, [Online]. In: Pesticides--Restricted and canceled uses. Environmental Protection Agency (Producer). Available: http://ww.epa.gov/oppfed1/international/piclist.htm [2005, December 19]. [55742]
153. Vestal, Paul A. 1952. Ethnobotany of the Ramah Navaho. Reports of the Ramah Project: No. 4. Papers of the Peabody Museum of American Archeology and Ethnology. Cambridge, MA: Harvard University. 40(4): 1-94. [37064]
154. Villena, Francis; Pfister, James A. 1990. Sand shinnery oak as forage for Angora and Spanish goats. Journal of Range Management. 43(2): 116-122. [10408]
155. Villena-Rodriguez, Francis. 1987. Nutrition of goats grazing sand shinnery oak (Quercus havardii) ranges in west Texas. Lubbock, TX: Texas Tech University. 102 p. Thesis. [11416]
156. Vincent, Dwain W. 1992. The sagebrush/grasslands of the upper Rio Puerco area, New Mexico. Rangelands. 14(5): 268-271. [19698]
157. Wade, Dale D.; Brock, Brent L.; Brose, Patrick H.; Grace, James B.; Hoch, Greg A.; Patterson, William A., III. 2000. Fire in eastern ecosystems. In: Brown, James K.; Smith, Jane Kapler, eds. Wildland fire in ecosystems: Effects of fire on flora. Gen. Tech. Rep. RMRS-GTR-42-vol. 2. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 53-96. [36983]
158. Weaver, J. E. 1968. Prairie plants and their environment: A fifty-year study in the Midwest. Lincoln, NE: University of Nebraska Press. 276 p. [17550]
159. Webber, John M. 1960. Hybridization and instability of Yucca. Madrono. 15: 187-192. [5764]
160. Webber, John Milton. 1953. Yuccas of the Southwest. Agriculture Monograph No. 17. Washington, DC: U.S. Department of Agriculture, Forest Service. 97 p. [2474]
161. Weber, William A.; Wittmann, Ronald C. 1996. Colorado flora: eastern slope. 2nd ed. Niwot, CO: University Press of Colorado. 524 p. [27572]
162. Wells, Philip V. 1970. Postglacial vegetational history of the Great Plains. Science. 167: 1574-1582. [2491]
163. Wendtland, Kyle J. 1993. Fire history and effects of seasonal prescribed burning on northern mixed prairie, Scotts Bluff National Monument, Nebraska. Laramie, WY: University of Wyoming. 188 p. Thesis. [43179]
164. White, Larry D. 1965. The effects of a wildfire on a desert grassland community. Tucson, AZ: University of Arizona. 107 p. Thesis. [5552]
165. Whitson, Tom D.; Burrill, Larry C.; Dewey, Steven A.; Cudney, David W.; Nelson, B. E.; Lee, Richard D.; Parker, Robert. 1999. Weeds of the West. 5th edition. Laramie, WY: University of Wyoming. 630 p. In cooperation with: Western Society of Weed Science; Western United States Land Grant Universities, Cooperative Extension Services. [35557]
166. Wilson, Gail W. T.; Hartnett, David C. 1998. Interspecific variation in plant responses to mycorrhizal colonization in tallgrass prairie. American Journal of Botany. 85(12): 1732-1738. [30311]
167. Wright, Henry A.; Bailey, Arthur W. 1982. Fire ecology: United States and southern Canada. New York: John Wiley & Sons. 501 p. [2620]
168. Wydeven, Adrian P.; Dahlgren, Robert B. 1985. Ungulate habitat relationships in Wind Cave National Park. Journal of Wildlife Management. 49(3): 805-813. [57]
169. Young, James A. 1991. Cheatgrass. In: James, Lynn F.; Evans, John O., eds. Noxious range weeds. Westview Special Studies in Agriculture Science and Policy. Boulder, CO: Westview Press, Inc: 408-418. [30594]
170. Young, James A.; Evans, Raymond A. 1981. Demography and fire history of a western juniper stand. Journal of Range Management. 34(6): 501-505. [2659]