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Wildlife, Animals, and Plants |
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BOTANICAL AND ECOLOGICAL CHARACTERISTICS
GENERAL BOTANICAL CHARACTERISTICS:Bottlebrush squirreltail is a cool season, [8] perennial bunchgrass native to the Intermountain West [18]. It is solitary [200], possessing solid, mostly flowering culms [210], with flat leaf blades. The inflorescence is a spike 0.8 to 6.7 inches (2-17 cm) long [82,150,200]. Ecotypic variation is common among bottlebrush squirreltail populations [9]. Reynolds and Fraley [164] found bottlebrush squirreltail roots to achieve depths of 39.4 inches (100 cm) below the soil surface. Depths below 39.4 inches (100 cm) were not seen due to a subsurface layer of basalt, suggesting rooting depths greater than 39.4 inches (100 cm) are possible. A lateral root extension of 16 inches (40 cm) was observed at 9.8, 20, 24 and 39.4 inch (25, 50, 60 and 100 cm) depths.
RAUNKIAER [163] LIFE FORM:Hemicryptophyte
REGENERATION PROCESSES:Bottlebrush squirreltail regenerates from surviving root crown [29,201] and seed [18]. Vegetative propagation is nonexistent [18]. Bottlebrush squirreltail has the ability to produce large numbers [99,214] of highly germinable seeds, with relatively rapid germination [214] when exposed to the correct environmental cues. Plants are self-fertilizing [55]. Seeds are readily dispersed by wind [15,99] a few days following maturation [18]. Dispersal is a function of bottlebrush squirreltail's long reflexed awns and disarticulating, mature inflorescence [99,131,148]. Seeds are dispersed when the spike inflorescence is carried along the ground by wind catching the long awns [131]. Although bottlebrush squirreltail has the potential for long distance seed dispersal, Martlette and Anderson [131] found natural plant cover to act as a barrier to dispersal. Wind dispersal of bottlebrush squirreltail seed did not exceed 131 feet (40 m), with viable seed remaining relatively close to mature bottlebrush squirreltail plants. Dormancy protects bottlebrush squirreltail seeds from germinating during seasonal dry periods. Dry seeds require a period of afterippening, which widens environmental conditions conducive to germination [18]. Allen and others [2] found germination rate increased and dormancy levels decreased as the duration of dry storage increased. Desert bottlebrush squirreltail seed commonly show higher levels of dormancy than seed from mountain populations [18]. Bottlebrush squirreltail seeds may germinate without a period of afterippening, showing a partial state of dormancy. However mean germination time for recently harvested seeds is longer than for afterippened seeds. Beckstead [19] evaluated the germination temperature requirements of recently harvested bottlebrush squirreltail seeds obtained from mountain and desert habitats. The greatest germination occurred primarily at 50/68 degrees Fahrenheit (10/20 °C) and 59/77 degrees Fahrenheit (15/25 °C), with higher temperatures of 68/86 degrees Fahrenheit (20/30 °C) inhibiting germination. Environmental conditions and timing of phenological events greatly affect the probability of recently harvested bottlebrush squirreltail seed germination. Temperatures of 50/68 degrees Fahrenheit (10/20 °C) and 59/77 degrees Fahrenheit (15/25 °C) are unlikely to occur during summer months in desert habitats. In higher, mountain habitats, summer temperatures of 50/68 degrees Fahrenheit (10/20 °C) and 59/77 degrees Fahrenheit (15/25 °C) may occur; however, bottlebrush squirreltail usually ripens later at higher elevations [19]. In general, recently harvested bottlebrush squirreltail seeds at lower elevations have a much greater probability of fall germination than seeds from higher elevations [2]. Chabet and Billings [40] observed germination of bottlebrush squirreltail seeds from alpine sites (10,793 feet (3,290 m)) in the Sierra Nevada. The greatest germination (%) occurred at day/night temperatures of 81/73 degrees Fahrenheit (27/23 °C (96%)) and 90/82 degrees Fahrenheit (32/28 °C (92%)).
SITE CHARACTERISTICS:Bottlebrush squirreltail has wide ecological amplitude [161], but it most commonly occurs in disturbed areas of deserts, valleys, foothills, and mountain meadows [18]. Regional: Bottlebrush squirreltail is found throughout Colorado on dry hills, plains, and rocky slopes, and within open woods and meadows [92]. In Montana, bottlebrush squirreltail occurs in dry, open habitats, from valley to timberline [123]. Throughout the western Great Plains, bottlebrush squirreltail is commonly found on dry soils of pastures and roadsides [82]. In Utah, bottlebrush squirreltail prefers dry to moist vegetation types, from salt desert shrub to alpine grassland [200]. Plains, rocky hills, or montane slopes are common sites in New Mexico [132]. In Arizona, open sandy ground, rocky hills, and open pine woods are common sites [115]. Bottlebrush squirreltail is common to dry rangeland areas of Kansas [154]. In central Washington, bottlebrush squirreltail prefers disturbed sites. Within these sites plant density is negatively correlated with individual plant size [153]. In California, bottlebrush squirreltail is found in scattered stands at high elevations on dry, gravelly soils. It is also common to hillsides and brush associations [168]. Soils: Bottlebrush squirreltail inhabits a wide variety of soil types and is tolerant of saline [108] and alkaline soils [168]. It is widely distributed in salt-desert shrub ranges of the west, on dry, gravelly soils, or within alkaline conditions. Bottlebrush squirreltail is found on clayey soils of northeastern California sagebrush communities [27]. Throughout Montana it occurs predominantly on dry, gravelly soils, in saline or alkaline areas [150]. Within alpine areas of Olympic National Park, Washington, bottlebrush squirreltail prefers well-drained, undifferentiated, disturbed, shallow and stony soils [21]. Passey and Hugie [158] found bottlebrush squirreltail to achieve better growth on Newdale silt loam soils than on Brunt silt loam, in areas with similar climate, slope, and exposure. Bottlebrush squirreltail may also occur on loose, ashy soil [11]. Bottlebrush squirreltail is not common within wet areas such as river lowlands and soil along irrigation canals [153]. Elevation by state:
SUCCESSIONAL STATUS:Depending upon habitat type, bottlebrush squirreltail may occur as an early, mid-, or late successional species. Shrub rangelands: Bottlebrush squirreltail is generally a dominant component of seral big sagebrush/bunchgrass communities [217]. Bottlebrush squirreltail is represented in early seral and climax stages of big sagebrush/bluebunch wheatgrass associations in Nevada. Tueller and Platou observed the most pronounced bottlebrush squirreltail during early and climax stages of big sagebrush/bluebunch wheatgrass associations in Nevada [190]. Bottlebrush squirreltail is found within seral and climax stages of big sagebrush rangelands in southeastern Idaho [4]. It is a component of climax big sagebrush communities in Idaho [205] and is a member of climax big sagebrush/western wheatgrass communities of Colorado [183]. Within shrub-steppe ecosystems of western Colorado, bottlebrush squirreltail is an early seral species [117]. Bottlebrush squirreltail also occurs in climax shadscale communities [100]. Pinyon-juniper communities: Bottlebrush squirreltail is common in mid-seral and climax pinyon-juniper communities of Mesa Verde, Colorado [67,68]. Bottlebrush squirreltail is a component of seral and climax western juniper (Juniper occidentalis) communities of the Pacific Northwest [54]. Ponderosa pine communities: Bottlebrush squirreltail is a member of interior ponderosa pine climax communities within the central and southern Rocky Mountains [209]. Prior to invasion of nonnative annuals in the Snake River Plain, Idaho, bottlebrush squirreltail occupied a mid to late seral status, suppressing the early seral fescues, sixweeks fescue (Vulpia octoflora), and foxtail fescue (Vulpia myuros) [160].
SEASONAL DEVELOPMENT:The wide ecological amplitude of bottlebrush squirreltail leads to differential timing of phenological events between individuals of differing habitats [43,109]. Flowering generally occurs in spring or early summer [18,57]. Lower elevation populations (that is, cold desert, salt desert habitats) usually mature early June with higher elevation populations (that is, mountain brush, mountain meadows) reaching maturity in late July [18]. Hironaka and Tisdale observed phenological differences between the subspecies Elymus elymoides ssp. elymoides and ssp. californicum. In a common garden experiment E. e. ssp. elymoides developed 10 to 14 days earlier than ssp. californicum [100]. Between 1960 and 1969, Murray and others evaluated bottlebrush squirreltail phenology in southern Idaho. Growth began from mid-March to mid-April. Flower stalks began to form late-April to mid-May, with anthesis occurring in early to mid-June. Plants were dormant from the middle of July to the end of August with fall regrowth occurring through October [152]. Clary [43] evaluated bottlebrush squirreltail phenology and rate of growth from different environments using a transplant garden and growth chamber. The timing of bottlebrush squirreltail phenological events and overall growth rate was closely related to homesite environmental conditions. Bottlebrush squirreltail individuals from higher elevations were limited by cold temperatures whereas individuals from lower elevations were limited by water availability and warm temperatures. Under the same environmental constraints, bottlebrush squirreltail from areas with low moisture stress and cool climates showed higher growth rates, attaining maximum height earlier than individuals from warmer drier sites. Bottlebrush squirreltail requires the longest time to flower in areas of relatively moderate temperature and moisture regimes: Time to flowering in days for bottlebrush squirreltail individuals from different habitats is shown below. Plants were grown at 6,490 feet (1,980 m) on a clay loam with an annual precipitation of 21.4 inches (544 mm) and annual temperature of 49 degree Fahrenheit (9.5 oC).
Bottlebrush squirreltail is responsive to fall rains in northern areas of the Great Basin, allowing for fall regrowth. Fall regrowth uses the majority of total available root carbohydrates partitioned during the summer [50]. The optimal soil temperature for root and shoot growth occurs at approximately 77 degrees Fahrenheit (25 °C). However, bottlebrush squirreltail shows continuous root growth down to 41 degrees Fahrenheit (5 °C) soil temperature [100].
Related categories for SPECIES: Elymus elymoides | Bottlebrush Squirreltail |
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