SPECIES: Coleogyne ramosissima
AUTHORSHIP AND CITATION:
Anderson, Michelle D. 2001. Coleogyne ramosissima. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ ..
FEDERAL LEGAL STATUS:
No special status
KUCHLER  PLANT ASSOCIATIONS:
K018 Pine-Douglas-fir forest
K019 Arizona pine forest
K022 Great Basin pine forest
K023 Juniper-pinyon woodland
K031 Oak-juniper woodland
K032 Transition between K031 and K037
K037 Mountain-mahogany-oak scrub
K038 Great Basin sagebrush
K053 Grama-galleta steppe
K054 Grama-tobosa prairie
K057 Galleta-threeawn shrubsteppe
K058 Grama-tobosa shrubsteppe
K059 Trans-Pecos shrub savanna
SRM (RANGELAND) COVER TYPES :
211 Creosotebush scrub
401 Basin big sagebrush
403 Wyoming big sagebrush
405 Black sagebrush
408 Other sagebrush types
412 Juniper-pinyon woodland
413 Gambel oak
414 Salt desert shrub
417 Littleleaf mountain-mahogany
504 Juniper-pinyon pine woodland
505 Grama-tobosa shrub
509 Transition between oak-juniper woodland and mahogany-oak association
HABITAT TYPES AND PLANT COMMUNITIES:
Blackbrush occurs both in essentially pure stands and as a component of several other vegetation types [6,104]. Nearly pure stands of blackbrush typically occur between the Mojave Desert creosotebush-white bursage (Larrea tridentata-Ambrosia dumosa) communities and the Great Basin sagebrush (Artemisia spp.) communities [8,16,17,106,110,118]. Blackbrush does not belong strictly to either Mojave or Great Basin vegetation types but occupies a position intermediary to that of creosotebush and sagebrush types [10,17,26,61,118]. At its lower boundary, the blackbrush association has relatively high species richness, and at its upper boundary blackbrush rapidly disappears when sagebrush appears . It dominates the ecosystems occurring in the lowest, driest portions of the Colorado Plateau portion of the Great Basin Desert  as well those in the transition zone [10,14,49,113,124]. Because blackbrush transcends the biome boundaries, its associates differ based on the adjacent biome . Blackbrush communities are generally bounded by creosotebush and Joshua tree (Yucca brevifolia) communities at the lower elevational limit and by juniper (Juniperus spp.) and big sagebrush (A. tridentata) communities at the upper elevational limit [17,18,74]. It is characteristic of the southern desert shrub vegetation of Nevada, occurring with creosotebush, bursage, and Joshua tree [7,9,56,66,108]. In the Mojave Desert scrub, subordinate shrubs include winterfat (Krascheninnikovia lanata), Mojave yucca (Y. schidigera), creosotebush, turpentine bush (Thamnosa montana), desert almond (Prunus fasciculatus), and purple sage (Salvia dorrii) [49,97]. In the Great Basin Desert scrub, common associates are sagebrush, shadscale (Atriplex confertifolia), winterfat, greasewood, and rabbitbrush (Chrysothamnus spp.) [67,109].
In California, blackbrush occurs as a subdominant species in the Mojave mixed woody scrub, and as a common understory species in pinyon-juniper (Pinus-Juniperus spp.) woodlands . It is characteristic of the northern desert scrub in Arizona [32,44], and is dominant in the canyon desert areas of northern Arizona, comprising 90% of the vegetation in areas where it occurs . Blackbrush is important in the Colorado pinyon (P. edulis)/blackbrush habitat type in northern Arizona . In Nevada, blackbrush forms a dominant association [106,125], is a primary shrub associate in the sagebrush association and the salt desert scrub association, and is a common associate in the creosotebush-white bursage, hopsage (Grayia spinosa), and Mojave mixed scrub associations . It is a subdominant in pinyon-juniper woodlands [4,5,13,21,103,106] and a codominant in stands of Joshua tree [1,61,77,103] and shadscale . It occurs as a dominant shrub in both pinyon-dominated and juniper-dominated woodlands, occurring in the following plant associations :
northern Mojave: singleleaf pinyon (P.
monophylla)/blackbrush/blue grama (Bouteloua gracilis); singleleaf
pinyon/blackbrush/wavyleaf Indian paintbrush (Castilleja
applegatei); singleleaf pinyon/blackbrush/ Sandberg bluegrass (Poa secunda);
Utah juniper (J. osteosperma)/blackbrush/blue grama,
Utah juniper/blackbrush/Indian ricegrass (Achnatherum hymenoides); Utah juniper/blackbrush/mutton grass (Poa fendleriana)
southeastern Great Basin: Utah juniper/blackbrush/bottlebrush squirreltail (Elymus elymoides)
In pinyon-juniper woodlands blackbrush is commonly associated with Joshua tree, Our Lord's candle (Y. whipplei), sagebrush, ephedra (Ephedra spp.), winterfat, and cactus (Opuntia spp.) [55,56,100,105,126].
Relative blackbrush density varies dramatically by plant community type; for example, 8,894 plants /ha were found in the blackbrush scrub community type, while 647 plants/ha and 0 plants/ha were found on Joshua tree woodland and Mojave mixed steppe sites, respectively . In 1 canyon in California, blackbrush cover ranged from 2.2% to 20.6% of total plant cover . In monospecific blackbrush shrublands, plant density and species diversity are much lower than in adjacent shrublands [36,54]. On blackbrush sites in Arizona, blackbrush contributed 82% to 95% of shrub cover . Though few other shrubs occur in these stands, red brome (Bromus madritensis ssp. rubens) and cheatgrass (B. tectorum) may be the dominant understory species [16,17,18,23]. At sites in southwestern Utah, blackbrush contributed 75% of all plant cover, with red brome and cheatgrass accounting for 12% . Big galleta (Pleuraphis rigida) also contributes substantially to understory vegetation in blackbrush communities . The blackbrush overstory tends to preclude extensive understory development [19,125]; however, herbaceous plants tend to occur in greatest abundance on the periphery of blackbrush canopies, indicating the presence of a more favorable microenvironment near the shrubs and a lack of any toxic effect exerted by blackbrush [17,23].
Blackbrush also commonly occurs with the following shrubs and grasses: fourwing saltbush (Atriplex canescens), desert bitterbrush (Purshia glandulosa), shrub live oak (Quercus turbinella), Cooper's heathgoldenrod (Ericameria cooperi), Fremont's dalea (Psorothamnus fremontii), white burrobush (Hymenoclea salsola), Anderson wolfberry (Lycium andersonii), broom snakeweed (Gutierrezia sarothrae), desert globemallow (Sphaeralcea ambigua), spiny mendora (Menodora spinescens), bladdersage (Salazaria mexicana), blue yucca, banana yucca (Y. baccata), galleta (Pleuraphis jamesii), threeawn (Aristida spp.), arid needlegrass (Achnatherum arida), desert needlegrass (A. speciosum), needle-and-thread grass (Hesperostipa comata), black grama (Bouteloua eriopoda), blue grama (B. gracilis), western wheatgrass (Pascopyrum smithii), and California buckwheat (Eriogonum fasiculatum) [1,5,13,16,62,65,69,71,89,95,96,107,118,119,124].
Blackbrush often occurs as nearly monospecific stands, with few other forage species available . Though it is not desirable deer forage, in areas where it is extensive it may experience heavy browsing pressure [8,68]. Where it forms an appreciable proportion of the brush cover, it provides a substantial part of the diet of domestic sheep and goats and deer, despite its small leaves and spinescent growth . In California, blackbrush has comprised up to 25% of the mule deer winter diet . Blackbrush-dominated sites where animals congregate may provide inadequate nutrition and impede the regeneration of bitterbrush, a key browse species . The presence of blackbrush in Arizona chaparral may reduce the range quality rating due to its low forage value and exclusion of higher forage value plants . Greater resistance to grazing probably allows blackbrush to persist and perhaps expand after the more palatable species are removed .
The spinescent character of blackbrush combined with low phosphorus and protein levels and high tannin levels result in low palatability [8,80]. New growth is likely more palatable and nutritious than old spinescent branches , but regrowth of blackbrush has been found to be unpalatable to domestic goats and cattle .
Blackbrush is low in phosphorus and protein and high in poorly digestible fiber [8,79,84,85]. Low nitrogen levels suppress microbial activity in the rumen, thereby decreasing fiber digestibility and lowering forage intake. High tannin levels, also typical of blackbrush, may depress intake by decreasing palatability and suppressing protein digestion . Domestic goats have been found to avoid blackbrush current-season growth in favor of older growth, even though new growth is higher in nitrogen and is more digestible. Current-season growth is high in concentrated tannins, which may deter browsing because tannins interfere with digestive or metabolic processes .
Twig nutrition varies by location on the plant; twigs
from basal branches, located within the canopy, are higher in crude protein and
in-vitro digestible matter than those on older, terminal branches, located at
the outer edges of the canopy [79,82,86]. Blackbrush nutrition has been evaluated according to plant part
[16,17,118]: the following table compares
the nutritional content of leaves and stems [16,17]:
|Ether extract (%)||Carotene (µ/g)||P (%)||Acid-detergent fiber (%)||Crude protein (%)||Lignin protein (%)|
Blackbrush leaves and stems exceed the minimum carotene required for gestating and lactating domestic animals but are deficient in phosphorus for domestic cattle and sheep during gestation and lactation [16,17]. Ether extract is comparable to that of big sagebrush and black sagebrush (Artemisia nova) during the winter [16,17].
Blackbrush provides cover for nongame birds and small mammals . In southern Nevada, blackbrush communities with an understory including big galleta are preferred cover for desert bighorn sheep .
VALUE FOR REHABILITATION OF DISTURBED SITES:
Blackbrush contributes to desert fertility by 1) protecting the soil against wind erosion through retarding the movement of soil and increasing the accumulation of fine soil particles around its base; 2) protecting understory vegetation from the effects of high temperatures, thereby helping to retain surface nitrogen and adding organic matter to the soil; and 3) serving as a nitrogen reservoir through the storage of nitrogen in roots, leaves, and stems .
Blackbrush displays no natural vegetative reproduction , but regeneration can be achieved with asexual propagation from artificial cuttings. One-year growth has been found to produce a higher percentage of rooted cuttings, more roots, and longer roots than older growth .
OTHER USES AND VALUES:
OTHER MANAGEMENT CONSIDERATIONS:
Dayton  considers blackbrush "almost worthless" forage. Nevertheless, blackbrush areas are economically important for winter grazing by domestic livestock, especially sheep, and by wild ungulates, primarily mule deer and desert bighorn sheep . Blackbrush is a native plant species resistant to trampling and recreation impacts . Solid stands of blackbrush may result in areas where overgrazing has removed the perennial grasses and palatable shrubs [16,17]. Blackbrush tolerates heavy browsing but survives at much reduced cover, and areas of blackbrush communities that have not been grazed have substantially more herbaceous vegetation than recovering, lightly, moderately, or heavily grazed sites [45,47,118,127]. A thriving blackbrush/desert needlegrass community exists at the Nevada Test Site, where grazing had been excluded. In adjacent areas that have been subject to grazing, the desert needlegrass component was virtually nonexistent .
Removal of spinescent material from blackbrush plants stimulates sprouting from basal and axillary buds; therefore, plants that are heavily browsed by livestock produce large quantities of new, more accessible growth [79,80,85,112]. Browsing improves nutritional quality of blackbrush twigs by increasing current-season growth; however, browsing may decrease palatability due to high tannin levels in current-season growth . Nutritional value varies in response to browsing treatments: low protein and high tannin content persists, though current-season growth generally has increased protein . Heavy browsing followed by 1 to 2 years of rest allows blackbrush to accumulate twigs that are more palatable because they are lower in tannins due to lower proportions of current-season growth [80,84,85,86]. Domestic goats can be used to remove spinescent growth and increase production of current-season growth to improve forage for cattle; however, the low crude protein levels may cause a reduction in livestock weight [83,112]. Livestock browsing on blackbrush should be supplemented with protein to improve rumen function and minimize weight loss [80,84,85]. With intensive management, stocking intensities of 1.8 AUM/ha can be maintained .
Blackbrush can produce substantially larger amounts of current growth with somewhat greater palatability and nutritional value through the use of mechanical or browsing treatments . Prescribed burning can lead to replacement by other shrubs, diversifying plant communities and increasing the winter forage base, which may increase livestock carrying capacity [8,112]. Because blackbrush exhibits strong apical dominance that suppresses annual twig growth, removal of terminal buds during the dormant winter season stimulates lateral twig growth during the spring [81,82]. Brush beating damages plants and stimulates growth of new shoots, improving forage quality . The results of a simulated brush beating in different plant communities 1 year after treatment are presented below. Blackbrush plants in the blackbrush association responded better to the brush beating treatments than blackbrush plants in either the Joshua tree/blackbrush or Utah juniper/blackbrush associations. The number of blackbrush plants (out of 30 at each location) is presented according to the response to brush-beating treatment and the plant community in which the blackbrush occurred :
|Location (plant community type)||# of blackbrush plants in each response category|
Efforts to manipulate blackbrush rangelands to increase forage production have produced unanticipated results . Blackbrush stands might be manipulated for improvement of forage quality and quantity without destroying the original vegetation; however, the manipulation may open the plant community to the invasion of other, perhaps less desirable, species .
Blackbrush has a diffuse and shallow root system . The greatest root biomass of blackbrush is found at a soil depth of 4 to 12 inches (10-30 cm), with few roots penetrating the fractured caliche layer, if present [16,79,84,85]. Large supporting roots are located directly beneath the plant, and root biomass tends to decrease with increasing distance from the plant and with increasing soil depth [79,84,85]. Shallow soils often result in a low root:shoot ratio and limited root development in blackbrush communities .
Blackbrush is evergreen [1,27,79,84,85,89,94,109], though it may lose substantial leaf area during the dry summer season . Blackbrush is drought-deciduous, avoiding water stress by becoming temporarily dormant and shedding older leaves as stress intensifies during the dry season . After leaf drop, it enters a long summer dormancy 
Atypical of the rose family [8,17], blackbrush flowers typically lack petals [38,68,90,123]. Blackbrush flowers are perfect, solitary, and terminal on the young branchlets . The fruits are dry, leathery achenes, 3 to 4 mm long, with a bent and twisted style [38,90,117].
Blackbrush has a "long" life span [92,121], and its life history emphasizes maintenance of existing individuals; establishment from seed is rare . Blackbrush-dominated stands are generally monotypic, simple communities where shrub cover is high. Close spacing permits little growth of other vegetation [8,16,17,41,45,58,79,84,85,94].
Blackbrush regenerates from wind-pollinated seed [64,102]. Fruits are large and heavy with no visible means of rapid dispersal; the only obvious means of dispersal are rodent activity and storm runoff [9,16,64,121]. Blackbrush is a mast species, and although winter precipitation initiates flowering, size of the resulting fruit crop is a function of available stored resources . The scarcity of blackbrush seedlings on sites in southwestern Utah indicates that blackbrush reproduction occurs infrequently . Blackbrush seed germination occurs in February or March and can occur from relatively deep in the soil [16,17,53]. Seedlings often appear in clusters from rodent caches [9,16,17,53,121]. Few seedlings are actually present in blackbrush stands. Due to several factors most seedlings do not survive past their cotyledon stage. Destruction by rodents digging up the cache for remaining seeds, soil erosion that exposes seeds and then covers them with debris, and limited soil moisture in the summer cause seedling mortality [16,17,60]. Infrequent and inconsistent seed set and seedling establishment may also result from herbivore browsing .
Blackbrush generally has a low germination rate [9,121], but with heavy, early spring rains, blackbrush seeds germinate in relatively large numbers. These may be the only conditions under which substantial germination occurs, suggesting that "pulse" climatic events are needed for establishment [9,10,121]. Soil moisture is required before seeds will break dormancy; watering at 2-week intervals was found to increase germination more than watering at 1- or 3-week intervals . Germination of blackbrush seeds requires cold stratification without light [16,17,53]. Germination has been found to increase from 53% with no treatment to 83% after 7 weeks of cold stratification at 39 degrees Fahrenheit (4 oC) [16,17,29,53]. Seeds have also been found to respond to a moist storage at 41 degrees Fahrenheit (5 oC) and germinate at that temperature .
Germination patterns vary as a function of climate and elevation. Seeds collected from low-elevation sites were less dormant than seeds from high elevation sites in southern Utah and Nevada; the seeds from the 3,930-foot (1200 m) sites required a shorter chilling period to increase germination response than those from the 5,085-foot (1550 m) sites . This relationship between dormancy status and site elevation may indicate that blackbrush has evolved ecotypes [53,75]. Dreeson and Harrington  found that substantial age and source differences are apparent in regard to population germination and/or stratification requirements. The sensitivity of seeds to salinity may be a limiting factor governing the distribution of blackbrush [17,118].Blackbrush has a slow growth rate [57,121] that may be the result of shallow soils and an often-present caliche layer, which impede root growth and soil moisture .
Blackbrush ranges typically occur at elevations between 2,500 and 8,000 feet (760-2440 m) [6,16,57,58,106,118], and distribution is strongly related to differences in precipitation, temperature, and soils . The upper elevation limit may be set by colder air temperatures, while the lower limit may be determined by cold air draining from adjacent mountain slopes into the valley bottoms [57,58], or by low soil moisture [17,57,58].
Blackbrush stands occur on well-drained sites including alluvial and colluvial slopes, washes, valley bottoms, lowlands, and flatlands of mild slope, and derived from limestone, sandstone, gneiss, and basalt [1,2,5,6,8,10,15,16,23,47,51,55,58,106,107,118,123,124]. Soils supporting blackbrush are generally shallow, poorly developed, and coarse textured, often with abundant exposed rock and high sand content [5,6,8,17,23,44,51,98,118,123]. These sites are also calcareous, moderately alkaline, and low in salinity [9,17,94,118] with pH ranging from 7.8 to 8.5 [16,17,23]. Blackbrush has a low tolerance for salinity, excessive soil moisture, and impeded soil aeration . Shrubs are often clustered on small mounds, evidently created by entrapment of wind-blown material . There is typically a well-developed microphytic crust on the soil surface between shrubs .
The shallowness of soil may in part determine the abundance and distribution of blackbrush [23,55]. Blackbrush is abundant on shallow soils with caliche layers [2,8,12,16,17,23,55,118,125], but is more abundant on adjacent, deeper soils . Blackbrush occurs on ancient granitic debris flows in California, with the cover and density of blackbrush increasing with the age of the debris [120,121]. On the oldest depositional area, blackbrush is nearly monospecific, and the only physical differences between the flows studied are those resulting from difference in geologic age; notably, the intermediate and oldest flows had caliche layers [120,121]. The association of blackbrush with old soils and the lack of it on young basalt flows implies either an allogenically controlled succession with blackbrush dominating  or an affinity of blackbrush for calcium carbonate irrespective of the age of the surface [121,125].
Blackbrush individuals alter the soil chemistry around their bases [16,17,121]. Bowns  found that percent totals of nitrogen and available phosphorus are higher in soil beneath blackbrush plants than in the spaces between, and both nutrients decrease with increasing soil depth .
Blackbrush is thought to be climax vegetation, occurring in late seral stages and generally dominating drier sites with residual or colluvial soil [16,17,107]. It forms stable vegetation assemblages on least disturbed geomorphic surfaces, and persists longer than other plant assemblages on these surfaces [54,107,121]. On some sites it is considered an invasive species, and may invade grasslands following overgrazing [8,16,17,122]. The occurrence of blackbrush on undisturbed, relict areas supports the idea that blackbrush is a climax species . Where dominant on undisturbed sites, blackbrush cover and density are substantially higher than on adjacent disturbed sites [120,121]. In the blackbrush association of the northern Mojave Desert, 1 study found 3.2 plants/100 m2 on disturbed, early-successional sites, compared to 17.9 plants/100 m2 on undisturbed sites . Blackbrush has been described as a mid- to late-seral species in California, increasing in occurrence at the expense of ephedra, wolfberry, and hopsage and forming nearly pure stands at the expense of all plant species except ephedra . Succession to blackbrush replenishes the soil for annuals because it provides better soil moisture conditions early in the season and higher nitrogen levels under the shrub canopy .
Blackbrush initiates shoot growth and sets leaves in March [1,2,16,17]. Twig and leaf growth are normally restricted to late March through mid-June, but because blackbrush summer dormancy results from a combination of low soil moisture and high temperatures, heavy summer rains may result in resumed growth in September and October [2,16,17,59,118]. When watered at 104 degrees Fahrenheit (40 oC), no growth occurred; however, when temperature was dropped to 89 degrees Fahrenheit (31 oC) new growth was initiated . In laboratory experiments, root growth and stem growth were better at 70 degrees Fahrenheit (21 oC) than at 61 (16 oC) or 82 degrees Fahrenheit (28 oC), indicating a narrow temperature tolerance [2,118].
Blackbrush flowers only in spring, probably the result of photoperiodism . Flowering is induced by moderate to heavy winter precipitation [9,56]. Increases in winter precipitation and resulting soil moisture contribute to an abundance of flowers and seeds . Flower buds begin to develop at the tips of terminal or lateral branches 2 weeks after the shoot growth begins and are fully open after 5 weeks [1,16,17]. By 6 weeks, 80 to 100% of the flowers are open, and no further twig elongation occurs once the flowers are fully developed [16,17]. Blackbrush at high elevations has a shorter flowering period than blackbrush at lower elevations, and flowering on individual plants is not synchronous, occurring over a 1- to 3-week period . Fruits begin to develop in late April and early May [1,16,17].
After growth ceases in June, older outermost leaves yellow and dry out. Abscission occurs in July and August, causing a large buildup of organic matter [1,2,16,17]. Blackbrush may lose most of its leaves during summer dormancy, but retains enough leaves at the ends of branches to be considered an evergreen species [1,2].
Blackbrush phenophases vary according to location within its range. The following table lists the mean initial date of each phenophase along an elevation gradient from 4,900 to 5,900 feet (1,500-1,800 m) in southern Nevada. Standard errors and significant ( p£0.05) differences are denoted by a and b, respectively .
|Phenophase||Lower ecotone||Pure stand||Upper ecotone|
|shoot budding||28 Feb + 4a||5 March + 4ab||10 March + 4b|
|leafing||8 March + 4a||14 March + 4ab||19 March + 3b|
|flower budding||28 April + 4a||28 April + 5ab||5 May + 4b|
|flowering||1 May + 5a||6 May + 5ab||13 May + 4b|
|fruiting||17 May + 5a||23 May + 4ab||29 May + 4b|
Because blackbrush is a nonsprouter, very susceptible to fire, and slow to reinvade sites, it is removed by fire [17,128], and succeeding communities are variable . Fire in blackbrush stands in southwestern Utah resulted in a variety of species dominating the postfire vegetation [3,17]. These postfire dominants include turpentine bush, desert bitterbrush, desert almond, big sagebrush, and some nearly monospecific stands of broom snakeweed . Grasses are more abundant in burned blackbrush communities , and burning may improve forage productivity . One 10-year-old burn in blackbrush was devoid of blackbrush and dominated by brittlebrush and desert mallow, with a denser cover of red brome and cheatgrass compared to exotic brome cover in the adjacent unburned blackbrush community . In another study of burned blackbrush sites in southwestern Utah, most shrubs were removed by fire. In the 1st postfire year, forbs greatly increased and grasses moderately increased. Forbs steadily decreased over time, approaching prefire levels, while grasses steadily increased, peaked at postfire year 6, and then declined to prefire levels. Shrub dominance on these sites returned within 20 years, but shrub composition after burning only slightly resembled composition before fire. Blackbrush cover was greatly reduced on all sites. Cryptogamic soil crusts associated with blackbrush communities were also strongly affected by fire. Before burning cryptogamic crusts contributed 9% of plant cover but were reduced to less than 1% of total plant cover after fire. There was very little evidence of crust formation after 19 postburn years . Fire has promoted succession to grassland by destroying the cryptogamic crust, which stabilizes the soil .
Blackbrush fire regime: The blackbrush association is composed of dense to scattered low-stature shrubs and dense to open grasses, and it maintains the highest cover of any desert shrub community. Blackbrush experiences a stand-replacement fire regime, though historical documentation of blackbrush fire cycles is limited. Frequent large fires have eliminated blackbrush from some areas. Fuel production in blackbrush ranges from 250 to 500 lbs/acre, and blackbrush is negatively associated with fine fuels of litter and grasses. Blackbrush occurs in areas with approximately 7 inches (180 mm) of annual precipitation, and cyclic desert precipitation above 10 to 14 inches (250-360 mm) may increase biomass and fuel continuity enough to increase fire behavior potential .
The following table provides some fire regime intervals for ecosystems where blackbrush occurs:
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|basin big sagebrush||Artemisia tridentata var. tridentata||12-43 |
|Wyoming big sagebrush||A. t. var. wyomingensis||10-70 (40*) [115,130]|
|saltbush-greasewood||Atriplex confertifolia-Sarcobatus vermiculatus||< 35 to < 100|
|desert grasslands||Bouteloua eriopoda and/or Pleuraphis mutica||5-100|
|grama-galleta steppe||B. gracilis-P. jamesii||< 35 to < 100|
|cheatgrass||Bromus tectorum||< 10|
|mountain-mahogany-Gambel oak scrub||Cercocarpus ledifolius-Quercus gambelii||< 35 to < 100|
|blackbrush||Coleogyne ramosissima||< 35 to < 100|
|Arizona cypress||Cupressus arizonica||< 35 to 200|
|Rocky Mountain juniper||Juniperus scopulorum||< 35|
|creosotebush||Larrea tridentata||< 35 to < 100|
|pinyon-juniper||Pinus-Juniperus spp.||< 35|
|Colorado pinyon||P. edulis||10-49|
|Arizona pine||P. ponderosa var. arizonica||2-10|
|galleta-threeawn shrubsteppe||Pleuraphis jamesii-Aristida purpurea||< 35 to < 100|
|mesquite||Prosopis glandulosa||< 35 to < 100|
|oak-juniper woodland (Southwest)||Quercus-Juniperus spp.||< 35 to < 200 |
PLANT RESPONSE TO FIRE:
Blackbrush is a nonsprouter after fire and does not aggressively return to burned sites [8,17,20,36,124,125,129,129]. A number of common desert shrubs and annuals occupy blackbrush sites after a fire, but very few blackbrush seedlings are usually present . Fire destroys the short-lived blackbrush seedbank , and blackbrush may take 60 years or more to reestablish after fire [17,72]. Blackbrush reinvades so slowly following fire that even after 35 years it may not be an important component of the vegetation .
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
Thatcher  observed the return of blackbrush following natural fires in a relict area of northwestern Arizona. The relict area developed under the influence of natural fire, without the influence of humans and domestic livestock. Natural fires in areas where blackbrush dominated did not materially alter the plant community: the community reverted immediately back to blackbrush without going through an intermediate plant association.
FIRE MANAGEMENT CONSIDERATIONS:
Fire can create more diverse plant communities from nearly monotypic blackbrush stands [8,17]. Prescribed burning has been used to promote forage-producing species in blackbrush communities  and to increase the herbaceous component in blackbrush communities . Conversion results vary; common successors include turpentine bush, desert bitterbrush, Mojave desertrue, banana yucca, Stansbury cliffrose (Purshia mexicana var. stansburiana), ephedra, desert almond, big sagebrush, broom snakeweed, red brome, and cheatgrass [8,24].
Fires may increase species diversity, livestock carrying capacity, and range condition. The following table describes 5 different sites and improvement of range condition after fire. All sites had cobbled, stony soils with 35% or more gravel content and received a mean annual precipitation of 125 mm .
Carrying capacity (acres/AUM & condition)
|Name of burn||Year||Acres||Current vegetative composition||Prefire||Postfire||Soil texture|
|Oak Creek||unknown||202.5||blackbrush, rabbitbrush, needle-and-thread grass, green ephedra||350/poor||37/fair||loam|
|Independence||unknown||202.5||Big sagebrush, green ephedra, CA. buckwheat||350/poor||21/good||sand|
|Symmes Creek 1||unknown||252.5||CA buckwheat, needle-and-thread grass||88/poor||15/poor||loam|
|Symmes Creek 2||unknown||305||CA buckwheat, needle-and-thread grass||350/poor||25/poor||sand|
|Symmes Creek 3||pre-1947||650||CA buckwheat, needle-and-thread grass||88/poor||11/poor||sand|
Prescribed burning on 3 southern Nevada sites killed the blackbrush cover, and the species failed to reestablish after as long as 28 years. Plant succession varied widely, with different plant species dominating on different burns, but the density of annual species was substantially increased in the 1st 3 years following burning. Replacement shrubs after fire were largely undesirable forages . Since sites may be highly suitable for blackbrush, burning these areas to convert them to grassland may give unpredictable or undesirable results . After burning on 3 proximal sites in southwestern Utah, 1 site was dominated by turpentine bush, desert bitterbrush, desert almond, and big sagebrush; another site established a pure stand of broom snakeweed, and a 3rd site established a pure stand of big sagebrush . Vast areas of blackbrush in Nevada were burned in the 1940s and 1950s. These sites were subsequently occupied by annuals and broom snakeweed and have been subject to recurring fires. In wet years, the burned areas had 8 to 10 times more herbage production than the range before it was burned, but herbs were very sparse in dry years . Site potential is an important consideration for burning blackbrush; fire may be more useful on areas with better-developed soils and potential to revegetate to more desirable plants . Widespread burning to reduce blackbrush is not recommended due to the unpredictability of successive vegetation, accelerated soil erosion, long-term or permanent removal of blackbrush, and damage to cryptogamic soil crusts [24,125,129].
Fire may be a necessary tool to modify fuel buildup; however, research is needed regarding management and restoration recommendations for blackbrush .
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