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Wildlife, Animals, and Plants |
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BOTANICAL AND ECOLOGICAL CHARACTERISTICS
GENERAL BOTANICAL CHARACTERISTICS:Green ephedra is a native, erect evergreen shrub [13,24] that is drought resistant and winter hardy [73,99]. Growth occurs in the cool season [65]. Green ephedra typically reaches 0.75 to 5 feet (.25 to 1.5 m) in height [18,65,69,99], though it has been reported to grow up to 6 feet (2 m) tall and 10 feet (3 m) wide [92]. It has numerous parallel stems that point upward resembling a broom, with branchlets clustered around nodes. Stems are generally less than 0.12 inch (3 mm) in diameter [18,19,99] and are bright green, with thicker growth developing gray, shreddy bark [18,99]. The jointed branches have small, scale-like, inconspicuous leaves growing opposite on the stem joints [65,69,111]. The fragile [5,75], deep-rooting system of green ephedra consists of several taproots extending almost straight down from the shrub's base, spreading only slightly and subdividing at intervals into somewhat smaller roots [4]. Green ephedra is dioecious [94], producing nut-like seeds partly or entirely enclosed in large bracts that form a cone structure [69]. It has been reported displaying spatial segregation of male and female plants [12,76]. RAUNKIAER [68] LIFE FORM:Phanerophyte REGENERATION PROCESSES:Green ephedra regenerates from seed and by sprouting
from the roots and woody crown. Green ephedra is readily established from seed [49,52,96], though seed production is
erratic under natural conditions, with an abundant seed crop occurring very
infrequently [111]. Seeds are
pollinated by wind [58,76], and seed dispersal occurs
via small mammals [58]. Seeds undergo a period of dormancy, which can
be broken by a 4-week prechill [60]. Constant warm temperatures decrease germination rates,
suggesting green ephedra responds to the stratification effect of cold periods
[111]. Seed remains viable for 5 years stored dry at 70 degrees
Fahrenheit (21 °C) [96]. Seed germination rates have not been
found to drop significantly over 15 years with temperatures ranging from
negative 21 to
101 degrees Fahrenheit (-29.9-38.3 °C) [84]. After 15 years stored in
an open unheated and uncooled warehouse, germination has
been found to decrease significantly, from 88% at 15 years to 24% at 20 years
(p<0.05). After 25 years, germination rates dropped to 2% [83]. SITE CHARACTERISTICS:Green ephedra is found on dry, rocky, open sites in valleys and washes, and on slopes, alluvial fans, mesas, and foothills [4,18,24,41,61,65,107,111]. It is typically found at elevations ranging from 3,000 to 7,500 feet (914-2,286 m) [1,13,14,48,55,65,80,107] though it has been reported at elevations up to 10,000 feet (3,048 m) in California and Utah [80,104]. Green ephedra has been reported growing on north [1,31,61], south [91], southwest, and west aspects [48]. Average precipitation on sites supporting green ephedra ranges from 8 to 15 inches (200-380 mm) [6,48], and green ephedra has been found to require 6 to 10 inches (150-250 mm) annual precipitation [65]. Green ephedra grows primarily on sandy, gravelly or rocky, well-drained, undeveloped soils [13,14,20,47,74,99]. Soil parent material is often granitic [1,49,90,106]. Green ephedra grows well on shallow, medium or deep soils [55,93,99] and is tolerant of calcareous, weakly saline, moderately alkaline, slightly sodic soils [6,34,71,87,99]. It is found on silty loam soils with low infiltration rates [87], but it is intolerant of wet, poorly drained sites [99]. The following sagebrush site characteristics are examples of sites where green ephedra occurs [93]:
Cover values for green ephedra vary based on site characteristics; in Arizona, washes with active soil and gravel deposition had a green ephedra cover value of .5%, while slopes above the washes that had shallow soils and little soil development had a cover value of 1.8%. The transition zone with stabilized soil formed from wash deposits but with no active soil movement had the highest cover value, 3.2% [24].
SUCCESSIONAL STATUS:Though not usually reported as a species of major importance, as a plant community component green ephedra occurs in early, mid-, and late successional stages [48,106]. It grows vigorously in full sun and more slowly in partial shade [99]. Green ephedra has been reported as having a cover value of 0% in the first stage (grass-forb) of succession in a pinyon-juniper woodland, 0.8% in the second stage (shrub-tree), and 0.1% in both the third and fourth stages (tree-shrub and tree, respectively) [49]. It appears in both shrub dominated and tree dominated pinyon-juniper and sagebrush sites in the Great Basin [86]. On Spy Mesa in Arizona, green ephedra was identified in both grass-dominated areas (early succession) and shrub-dominated (mid-succession) areas of a pinyon-juniper woodland [87]. In a pinyon-juniper woodland where no successional change occurred over 23 years, green ephedra plants and clumps demonstrated variable increases and decreases in size [91], and green ephedra was present in a nearly mature pinyon-juniper woodland at less than 1% cover [106]. Green ephedra is considered weakly competitive due to its slow growth rate [99]
SEASONAL DEVELOPMENT:Vegetative growth of green ephedra occurs during the cool season [65]. Seed development begins in the spring and seeds mature by late summer [99,111]. Seed maturation dates have been established at July 15 to September 1 [75]. Green ephedra seed germination occurs following a minimum 4-week chill to break seed dormancy [60].
Related categories for SPECIES: Ephedra viridis | Green Ephedra |
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