Coastal Sagebrush

Artemisia californica is the common sagebrush of chaparral in southern California. Its threadlike leaves and green flowering heads distinguish it from any other shrub in California. Artemisia nesiotica, an endemic of the Channel Islands that was initially considered a morphologic variant of A. californica, is distinct in size and form. Systematic placement of the complex may be problematic. The molecular phylogeny of L. E. Watson et al. (2002) suggests an alignment of A. californica within subg. Tridentatae. Based on this finding, a subgeneric realignment of this species may be in order. The odor of A. californica is markedly like that of the culinary mints known as common sage (Salvia species).

Shrubs, (20–)150–250 cm (rounded), pungently aromatic. Stems relatively numerous, arched, green or brown, branched (slender, wandlike, bases brittle), densely canescent to glabrate. Leaves cauline, light green to gray; blades filiform or spatulate to obovate, 3–5(–9) × 0.5–2 cm, sometimes pinnately lobed (lobes filiform, 0.5–1 mm wide), faces sparsely to densely hairy. Heads (nodding at maturity, pedunculate) in paniculiform arrays 6–20 × 1–3 cm (branches erect to broadly spreading). Involucres globose, 2–3(–4) × 2–4(–5) mm. Phyllaries broadly ovate, sparsely canescent. Florets: pistillate 6–10; bisexual 18–25; corollas pale yellow, 0.8–1.2 mm, glabrous. Cypselae ellipsoid, 0.5–1.5 mm, resinous (pappi coroniform). 2n = 18.

Artemisia abrotanoides Nuttall; A. fischeriana Besser; A. foliosa Nuttall; Crossostephium californicum (Lessing) Rydberg

More info for the terms: cover, density, frequency, litter, seed, severity, shrub, shrubs, wildfire

Increased postfire production
Three years following a prescription fire in a Morro manzanita (Arctostaphylos
morroensis) community, California sagebrush cover and frequency
substantially increased. The burn, located in Montaña de Oro State Park,
was conducted on 4 November 1998. Air temperature
during the fire was 61 °F (16 °C),
and relative humidity ranged from 50%
to 60%. Flame lengths as great as 50 feet (15 m) were observed. In places,
litter was still smoldering 24 hours following ignition. Prior to the fire,
California sagebrush cover and frequency were 0.4% and 8.0%, respectively. In postfire year
3, cover and frequency increased to 7.0% and 61.0%, respectively. As a result of
the burn, pure stands of Morro manzanita were transformed to mixed stands of
native California sagebrush, coyote bush, and orange bush monkeyflower
(Diplacus aurantiacus), and nonnative hottentot fig (Carpobrotus
edulis), perennial veldtgrass (Ehrharta calycina),
and narrow-leaved iceplant (Conicosia pugioniformis) [162].

On Otay Mountain, in southwest San Diego County,
2 "high-severity" wildfires during the summers of 1979 and 1980 caused
high mortality of California sagebrush. The fire in August
1979 caused >95% mortality of California sagebrush plants. During the summer of 1980, an
arsonist set fire to a portion of the site that burned in 1979. Where fire
burned in both 1979 and 1980, the mortality rate of California sagebrush was >96%. Prior to the 1979
and 1980 fires, the density
(no./m² ± SD)
of mature California sagebrush
shrubs was 0.22 ± 0.06 on sites that burned only in 1979 and 0.26 ± 0.06 on sites
burned in 1979 and 1980. While no data exist on California sagebrush seedlings prior to the 1979 fire,
seedling densities after the 1979 and 1980 fire where
2.62 ± 0.30/m² and 0.39 ± 0.12/m²,
respectively. When combining seedlings and mature shrubs that survived fire,
the relative abundance of California sagebrush in May 1981 was 9.20 times greater on sites
burned only in 1979 and 0.78 times greater on sites burned in both 1979 and 1980
compared to abundance of mature shrubs before fire at both sites. Since the mortality
rate of mature shrubs was so high, nearly all California sagebrush observed in 1981 were
seedlings and not sprouts [216,217].

Postfire sprout/seedling regeneration:
Sprouting of California sagebrush in postfire year 1 is common, but seedling
establishment generally does not occur until at least postfire year 2. The Agoura-Kanan
Fire, located in the Santa Monica Mountains, burned on 23
October 1978. The 2 study sites investigated, Encinal Canyon and Kanan-Dume, had
been fire free for 22 and 11 years, respectively. Both sites are located on the
coastal side of the range. California sagebrush sprouting and seedling recruitment were
assessed in May 1979 (postfire month 7) and May 1980 (postfire month 19).
There were no seedlings in postfire year 1, but sprouts flowered and set
seed in abundance in year 1, facilitating a large flush of seedlings in postfire
year 2 in Encinal Canyon. The following table reflects California sagebrush
sprouts and seedlings as a percent of total community density at both sites in postfire
years 1 and 2 [114].

 
Kanan-Dume
Encinal Canyon
May 1979 May 1980 May 1979 May 1980
% sprouts 13 19 1 5
% seedlings 0 1 0 30

Total seedling establishment on 6 burned sites far outpaced California
sagebrush sprouts. Two years following a late October 1978 fire that burned 20,000 acres (10,000
ha) on the coastal side of the Santa Monica Mountains, Malanson and O'Leary [128]
sampled the number of California sagebrush
sprouts and seedlings on 6 burn sites. Prior
to the 1978 fire, the sites had not burned for 22 years. Site 1 is on
south-facing sandstone; site 2 is on north-facing sandstone; sites 2 and 4 are
on east-facing sandstone; and sites 5 and 6 are on west-facing shale. Sites 1
through 4 burned in mid-afternoon during a period of low humidity (10-15%).
Sites 5 and 6 burned at 2 a.m., with a relative humidity from of 40% to 45% [128].

Site 1 Site 2 Site 3 Site 4 Site 5 Site 6
Sprout (no. /ha) 3,437 312 312 312 781 625
Seedlings (no. /ha) 7,500 156 312 56,719 469 6,250

Malanson and O'Leary 1985 [129] returned to the burn site at postfire year
4.5 to measure the canopy size of California sagebrush on the 6 sites. California
sagebrush canopy size was assessed on high intensity (6,100 kcal/m²) and low intensity (5,600 kcal/m²)
burn sites, on andesite and sandstone substrates, and on south-, north-, and
east-facing slopes. California sagebrush canopy was greatest on low-intensity burns, on andesite
substrates, and south-facing slopes. Of the 5 species measured (California
brittle bush, black sage, coastal buckwheat (Eriogonum cinereum), and San Luis purple sage),
California sagebrush had
the smallest total canopy size of all species. California sagebrush
canopy coverage was [129]:

Site characteristics Canopy size (m²)
High intensity burn 779 (6,327*)
Low intensity burn 962 (9,327)
Andesite substrate 985 (5,623)
Sandstone substrate 419 (5,984)
South-facing slope 985 (6,105)
North-facing slope 107 (2,206)
East-facing slope 597 (5,774)

*total canopy size of all 5 species combined

Postfire comparisons in coastal and interior sage scrub communities:
Over a 10-day period in late October and early November 1993, over 200,000 acres (80,000 ha) of
chaparral and coastal sage scrub were burned by wildfire. The severity of the fire
ranged from low to high and affected areas that had not burned from 3 to 85
years ago. On coastal sage scrub burned sites, peak vegetative recovery occurred in late
spring. During late spring, the ratio of California sagebrush seedlings to prefire shrubs was
approximately 15:1, and the ratio of California sagebrush sprouts:prefire shrubs was
approximately 0.3:1. The lower ratio of sprouts to prefire shrubs was due in
large part to complete fire mortality of many California sagebrush shrubs.
Measurements were also taken of the basal diameter and height of
both nonsprouting (dead) and
sprouting (live) postfire California sagebrush skeletons. Not surprisingly, the height of
sprouting California sagebrush shrubs was significantly (p<0.001)
greater than the height of nonsprouting shrubs. The basal
diameter of sprouting shrubs was significantly (p<0.001) less than
nonsprouting shrubs. This suggests that juvenile shrubs are better suited to
survive and sprout following fire than older shrubs. The numbers in
parentheses in the following table indicate the number of California sagebrush shrubs sampled [111].

Shrub status

Basal diameter
(mm ± SD)

Height
(cm ± SD)

Nonsprouting 32 ± 1 (952) 19 ± 1 (951)
Sprouting 11 ± 1 (376) 32± 2 (376)

Following the 1993 fires, the percentages of sprouting California sagebrush
plants and the seedling:parent ratio were evaluated
in postfire year 1 on coastal sage scrub and interior sage scrub communities. The number of parents was based on
the census of shrub skeletons, and seedling ratios were evaluated only for sites
with more than 5,000 seedlings/ha. Of the 11 shrub skeletons present in coastal
sage scrub and 19 in interior sage scrub, 18 ± 8% (mean ± SD)
and 20 ± 6%
had sprouted following fire, respectively. Of the 2 parent plants found in
coastal sage scrub and 23 in interior sage scrub, 15 ± 0
and 33 ± 10 seedlings/plant were measured,
respectively [113].

The total California sagebrush seedling recruitment for all 5 years
(no. of seedlings/ha ± SD) in chaparral
communities following the 1993 fire was 11,600 ± 4,800
and 31,500 ± 10,600 in sage scrub communities. Approximately 83% of all seedlings
recruited established during postfire years 1 and 2 [113].

Postfire diversity: One year
after the 1993 fires, species densities
(no. of species/0.1 ha ± SD)
in coastal sage scrub and interior sage scrub communities codominated by California sagebrush were 35.4± 2.1
and 58.5 ± 2.4, respectively. At the end of
postfire year 5, species density in coastal sage scrub and interior sage scrub communities
averaged 72.3 ± 1.9 and 94.7 ± 2.4, respectively. Further, by the end of postfire
year 5, coastal sage scrub communities were significantly (p<0.05) closer to their prefire plant
density than in postfire year 1. While interior sage scrub community densities
were more similar in postfire year 5 to prefire levels than during postfire year
1, the change was not significant [112].

California sagebrush

coastal sagebrush

California sagewort

California mugwort

Information on state-level protected status of plants in the United States is available at Plants Database.

More info for the terms: achene, adventitious, cover, fruit, litter, presence, root crown, sclerophyllous, shrub

This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g., [60,94,155,156,210]).

California sagebrush is a drought-deciduous subshrub [14,21,30,52,63,93,168,210] with several to numerous stems arising from the root crown [79]. It grows to a height of 2 to 5 feet (0.5-1.5 m) and is the tallest shrub in the coastal sage scrub community [146,155,156,210]. Lower branches are woody and generally do not exceed 0.2 inch (50 mm) in diameter [129]. California sagebrush branches support numerous leaves from 0.8 to 2 inches (2-5 cm) long and 0.5 to 1 mm wide [79,155,156]. Leaves are seasonally dimorphic [203]. Leaves attached to the main branches or stems are slightly larger and appear early in the growing season. Most of the larger leaves remain on the stem during the dry season, although they may wilt [68,70,204]. On lower branches, side-shoots develop from the leaf axils of larger leaves. The side-shoots develop smaller, persistent leaves [70,72]. The smaller leaves remain wilted for long periods of time under water stress and rehydrate within hours of rainfall [204]. Due to the presence of terpenes, leaves are highly aromatic [93,209]. The inflorescence, 4 to 12 inches (10-30 cm) long and 0.4 to 4 inches (1-10 cm) broad [79], produces 20 to 50 flower heads, with each head containing 15 to 30 disk florets [79,146]. Inflorescences also produce 6 to 10 pistillate flowers [60,94]. California sagebrush flowers are normally yellowish or brownish in color, but along desert borders they are commonly red [79]. The fruit, an achene, is extremely small and lightweight (60 µg/seed) [15,54,79,146].

Allelopathy: The essential oil from California sagebrush contains 5 toxic terpenes. It has been suggested that the release of terpenes by California sagebrush contributes to the relative lack of vegetation under and adjacent to the shrub [82,121,213]. During the 1st rains of December, the leaf drip from California sagebrush is toxic. The rain leaches toxins from the leaves and litter that is absorbed by the soil, adding to toxins previously deposited by volatilization during the dry season [116].

Community structure and productivity: In a coastal sage scrub community in the Santa Monica Mountains, California sagebrush and black sage comprise approximately 75% of the community cover. The mean annual aboveground live biomass, mean annual aboveground primary production, and litterfall of the coastal sage scrub community are 925 g/m², 355 g/m², and 199 g/m², respectively [68]. Similar research in the Santa Monica Mountains assessed the biomass and production of California sagebrush in stands burned 22 years prior to the measurements. California sagebrush peak aboveground biomass (June) and net annual production are presented in the following table [72]:

  Foliage Wood Dead Twigs Inflorescences Twigs Total Peak aboveground biomass (g/m² 51.4 377.4 101.4 ----* ---- 530.2 Net annual production (g/m²/yr) 31.3 ---- ---- 3.1 20.6 55.0 *No data

Photosynthesis/transpiration: California sagebrush plants have a thin leaf cuticle and numerous stomata that allow for a high photosynthetic rate in response to water availability. Consequently, California sagebrush has a higher transpiration rate and a longer period of water stress than sclerophyllous species with thick leaves and deep roots [57,139,146].

Roots: California sagebrush plants have fragile, fibrous roots that penetrate shallowly into the soil [9,30,92,139,146,163]. The shallow root system allows for rapid soil moisture absorption and growth at the beginning of the rainy season [56,139,146].

Adventitious rooting was observed within California sagebrush communities at Starr Ranch, Orange County. The development of adventitious roots occurred at the basal portions of their stems, an area covered with soil from erosion or silt deposits. In areas of packed soil, adventitious roots did not occur in California sagebrush. Of 98 California sagebrush plants sampled, approximately 10% exhibited adventitious roots [122].

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California sagebrush is endemic to California [60,107,155,156] and Baja California [118,204,210]. The distribution of California sagebrush is categorized within 4 major floristic associations. The floristic associations and their ranges are as follows: 1) Diablan: found from San Francisco region south to northern Santa Barbara County; 2) Venturan: a coastal group found from northern Santa Barbara County south through coastal Los Angeles County; 3) Riversidian: a cismontane inland group found from inland Los Angeles County, western Riverside County, and inland San Diego County; and 4) Diegan: a Baja-influenced group found from Orange County and coastal San Diego County south into northwestern Baja California [13,204]. California sagebrush distribution and occurrence is greatest in the Riversidian floristic association [202]. California sagebrush also occurs on some of the Channel Islands (Santa Clemente, Santa Catalina, Santa Cruz, San Miguel, San Nicholas, and Santa Rosa ) [146,155,169,205]. In Baja California, California sagebrush extends 200 miles (325 km) south of the Mexican border to approximately El Rosario [5,51,118,204]. Plants Database provides a distributional map of California sagebrush.

More info for the terms: charate, cover, fire frequency, fire regime, fire-return interval, forest, frequency, mean fire-return interval, natural, root crown, seed, shrub, stand-replacing fire

Fire adaptations: California sagebrush establishes after fire by seed [62,108,109,110,146,200,201,204] and sprouting from the root crown [45,78,125,126,127,128,129,130,200,201]. Vegetative sprouting is the primary postfire regeneration method, occurring in the 1st year after fire [146,204]. Seed dormancy can be broken by light, charate, or a combination of those factors; in part, that response is likely an adaptation to fire [17,108,109,110,146,161].

FIRE REGIMES: There is some disagreement over the historic fire-return interval for coastal sage scrub communities. At one end of the spectrum, Paysen and others [167] estimate the fire return interval to range from <35 to <100 years. At the other end of the spectrum, O'Leary [160] believes the natural fire frequency in coastal sage scrub is near the lower end of a 20- to 40-year cycle common in adjacent chaparral communities. Vogl [194] estimates an average fire-return interval of 20 years for lightning-ignited fire in chaparral adjacent to coastal sage scrub. While the historic fire-return interval may have ranged from ~20 to 100 years, loss of historic range due to development, agriculture, human-caused fires, and vegetation type conversion has altered FIRE REGIMES in coastal sage scrub communities [5,40,51].

Anthropogenic influence in coastal sage scrub has altered the fire-return interval to as short as 5 to 10 years or less on some sites [39,160]. In Santa Monica Mountains coastal sage scrub communities, fire data (all fires ≥0.1 ha) were assessed for the period 1909 to 1977. For the time period covered (68 years), the average interval between fires was 14 years for coastal sage scrub [133]. For the same time period, Hanes [85] suggested the fire return interval in coastal sage scrub communities in the San Gabriel and San Bernardino mountains was 2 to 10 years. The introduction of Mediterranean annual grasses, which often provide continuous ground cover of flash fuels, has severely altered the historic fire regime in coastal sage scrub [66]. Prior to 1960, the historic fire-return interval was 30 years in coastal sage scrub communities in western Riverside County. Over the past 20 years, however, nonnative grass cover has increased and altered the fire-return interval to less than 8 years [40] and likely as short as 2 to 5 years [5,6].

Shortened fire-return intervals may greatly reduce California sagebrush coverage [146]. Computer modeling conducted by Malanson [127] suggests that California sagebrush is eliminated from the shrub canopy within 100 years when fire-return intervals are less than 40 years. Other modeling predicts California sagebrush can handle fire intervals no shorter than 10 years [21]. While decreased fire frequency is of concern, it is likely that California sagebrush can withstand fire-return intervals shorter than every 40 years. California sagebrush is a common understory species in Monterey pine (Pinus radiata) forests at Swanton Pacific Ranch. Using fire scar data, Stephens and others [183] estimate that the mean fire-return interval for the years 1893 to 1976 ranged from 11.4 to 20.1 years. In the Santa Monica Mountains, California sagebrush cover is greatest (32.6% to 50.8%) on sites that burn approximately every 21 to 22 years [125]. For a California sagebrush-eastern Mojave buckwheat community on the Cleveland National Forest, fire records show that stand-replacing fire occurs at approximately 28-year intervals [208].

The following table provides fire return intervals for plant communities and ecosystems in which California sagebrush is important. Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".

Community or Ecosystem Dominant Species Fire Return Interval Range
(years) California chaparral Adenostoma and/or Arctostaphylos spp. 20 to 100 [5,7,40] coastal sagebrush Artemisia californica <35 to <100 California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [167] California steppe Festuca-Danthonia spp. <35 pinyon-juniper Pinus-Juniperus spp. <35 [167] California oakwoods Quercus spp. <35 [11] coast live oak Quercus agrifolia 2-75 [77]

More info for the terms: cover, duff, fire exclusion, fire frequency, fire suppression, frequency, fuel, litter, natural, seed, shrub, wildfire

Avian community dynamics: Several studies have found that bird species preferentially chose unburned coastal sage scrub communities over recently burned sites. Stanton [182] studied bird populations in a burned and unburned coastal sage scrub community 2 years following prescribed burning in Los Angeles County. While many bird species were found at both sites, more species and individuals selected the unburned site, which offered better foraging opportunities. On the unburned site, the bird population remained relatively steady throughout the year. The population on the burned site fluctuated, with greatest use in the spring [182].

Late-successional California sagebrush communities provide critical habitat for the federally threatened [192] California gnatcatcher [21,132,212]. California gnatcatcher nesting sites were surveyed at coastal sites in Riverside and San Diego counties. Burned and adjacent unburned plots, which had not burned for 22 years, were sampled at postfire year 3. California gnatcatcher nests were found at all unburned sites (n≥5). California sagebrush cover on unburned sites ranged from 4.2% to 78.4%. No nests were found at the burned sites (n=7) in postfire year 3, and California sagebrush cover ranged from a trace to 11.8%. California gnatcatcher nesting site requirements include a shrub cover of at least 50% and a minimum average shrub height of 3 feet (1 m); neither of these requirements was met on the 7 recently burned sites [21]. Beyers and Peña [22] and Mayer and Wirtz [132,212] conducted similar studies within burned and unburned sites. In both studies, California gnatcatcher highly preferred unburned sites.

For 1 year following a wildfire in Box Canyon, Los Angeles County, bird populations were counted and compared in burned and unburned areas. Bird censuses were taken 20 times during the year following the fire. Of the 72 species seen at both sites, slightly but not significantly more birds were concentrated on the unburned site [151].

Fire suppression: In coastal sage scrub, fire suppression has generally been successful in summer months devoid of extremely high temperatures accompanied by Santa Ana winds in fall. Where fire suppression has been successful year-round, delayed burning has resulted in abnormally large fires when the abovementioned weather conditions occur [127]. Coastal sage scrub is generally closer to developed areas than chaparral and is thus susceptible to accidentally and arsonist-set fire, thus increasing fire suppression activities. The long-term effect of fire exclusion on California sagebrush and other coastal sage scrub species in unknown. Zedler [214] stated that increased fire frequency in some coastal sage scrub communities is likely not natural, and fire suppression may be necessary to restore the communities to presettlement conditions. Conversely, some researchers suggest that fire exclusion facilitates the invasion of coastal sage scrub species into adjacent communities. Epling and Lewis [58] state that California sagebrush and other coastal sage scrub species are successfully invading chaparral communities dominated by sprouting species following abnormally hot, stand-replacement fires resulting from fuel buildup facilitated by suppression measures. Research conducted by Thomas [187] found that California sagebrush is invading adjacent valley oak (Quercus lobata) woodlands in the Santa Monica Mountains National Recreation Area.

Fuel loading: California sagebrush dominated communities biomass varies from 3 to less than 15 tons/acre, and approximately 70% to 85% of the biomass is consumed by hot fire [75,159]. In a California sagebrush-common deerweed community, total aboveground fuel load was 13.2 tons/acre. Aboveground live and dead biomass was 3.7 and 2.8 tons/acre, respectively, and duff and litter biomass was 6.7 tons/acre [159].

Prescription burning: Prescription burning of California sagebrush is not advised for several reasons. Since fire can deplete seed banks and kill adult plants, regular burning may reduce California sagebrush [127]. Further, prescription burning may favor further encroachment of Mediterranean grasses (red brome, ripgut brome, wild oats (Avena spp.), and annual sixweeks grasses (Vulpia spp.)) into California sage scrub communities [5]. If prescription burning is undertaken in coastal sage scrub, spring is the favorable season since less heat is generated by fires [72]. Guidelines for developing a fire prescription management plan in coastal sage scrub are available in the literature [74,75].

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More info for the term: phanerophyte

RAUNKIAER [172] LIFE FORM:
Phanerophyte

More info for the terms: allelopathy, cover, frequency, grassland, litter, presence, shrub, shrubland, shrubs

California sagebrush is primarily associated with coastal sage scrub sites, but has limited occurrence in chaparral communities. It is best developed on the coastal side of mountains below chaparral [85,88].

Air pollution: California sagebrush is sensitive to sulphur dioxide pollution. A significant (p<0.01) decrease in California sagebrush foliar cover occurred in shrubs located from 1,600 to 4,900 feet (500-1,500 m) downwind from an oil refinery's sulphur dioxide stacks near Santa Maria, California. Annual sulphur dioxide concentrations (25-year period) emitted from the oil refinery range from 0.09 to 0.17 ppm [171]. Further studies have been conducted on the response of California sagebrush to air pollution in the Santa Monica Mountains near Los Angeles. Where above-average levels of sulphur dioxide and ozone persist, visible foliar damage (fasciated stems) was present [206].

Aspect: California sagebrush plants located on north-facing sites of coastal sage scrub in southeastern Orange County are significantly (p<0.001) taller and have significantly (p<0.002) greater aerial cover/shrub/m² than plants on south-facing sites [54].

Aspect Height (m ± SD) Aerial cover/shrub/m (± SD) North 1.34 ± 0.04 1.04 ± 0.10 South 1.11 ± 0.05 0.59 ± 0.09

At 120 sites in southern California, the frequency (%) of California sagebrush on 2 aspects and 3 slopes was measured. The averages are presented in the table below [118]:

Community type Aspect Slope North-facing South-facing 0-5° 6-15° 16+ California sagebrush 9 12 8 17 8 California sagebrush-eastern Mojave buckwheat-white sage 13 16 23 17 12 California sagebrush-coyote bush-basin wildrye 9 3 8 6 6 San Luis purple sage-California sagebrush 30+ 10 8 17 22 California brittlebush-California sagebrush 0 10 0 3 8

Climate: California sagebrush primarily occurs in the mediterranean climate zone, which is characterized by hot, dry summers and mild, moist winters [62,118]. California sagebrush has a bimodal distribution in that it can occur in both the coastal plain, maritime climate and the hot interior of the coastal valleys [40,84,93]. Average yearly precipitation ranges from 10 to 18 inches (250-450 mm) [18,30,40,50,54,118,149,166,207], and approximately 90% of the precipitation falls between November and April [18,40,50,118].

In a modeling experiment, Malanson and others [131] estimate that optimal California sagebrush growth occurs when precipitation ranges from 4 to 10 inches (100-250 mm), the coldest winter temperatures range from 50 °F to 54 °F (9-12 °C), and the warmest summer temperatures range from 75 °F to 81 °F (24-27 °C). Extensive climatic data from the San Gabriel Mountains where California sagebrush is dominant can be found in the review by Miller [138].

Community zonation: Where California sagebrush encroaches into grasslands, the area surrounding California sagebrush generally looks bare. The bare zone, often 3 to 6 feet (1-2 m) wide, has been attributed to allelopathy, animal influences, and soil moisture [16,57,98,116,116,118,150,153,154,173,209].

Though appearing bare in comparison to the grassland and shrub communities, the bare zone is actually comprised of short herbs approximately 1 inch (3 cm) tall. Bare-looking zones generally occur around large, dense shrub assemblages, not where individual or scattered shrubs occur [80,81,116].

At 2 sites, 1 near La Purisima Mission, the other at the base of the Santa Ynez Mountains, Halligan [80] researched possible causes of bare zones surrounding California sagebrush stands. To test the hypothesis that herbivory and granivory causes bare zones between grasslands and shrub zones, the researcher fenced in a 3,400 ft² (320 m²) area encompassing grassland, the bare zone, and shrubland. Following 1 year of protection, the grassland had invaded 20 inches (40 cm) into the border zone. During the same period in an unprotected area, the grassland regressed from the shrub stand, leaving the border zone 30 inches (70 cm) wider. Within the new border zone, an abundance of brush rabbit feces was present and short animal trails were noticeable, suggesting that small mammals play a part in the creation of bare zones. The research further concluded that California sagebrush allelopathy was a minor contributor to the creation of bare zones. The growth of 2 common herbs, coast tarweed (Madia sativa) and smooth catsear (Hypochaeris glabra), planted under California sagebrush and exposed to the shrub's volatiles, was significantly inhibited (p<0.05). However, 2 common grass species (ripgut brome (Bromus diandrus ssp. rigidus) and rattail fescue (Vulpia myuros)) were not significantly affected by California sagebrush allelopathy. Halligan also found that soil moisture, rainfall, and throughfall of precipitation in the shrub zone are more variable than in grasslands, which also plays a minor part in the presence of bare zones. Further research is available on bare areas associated with California sagebrush [81,83].

Elevation: California sagebrush occurs from 0 to 3,000 feet (0-800 m) but is most common from 500 to 1,500 feet (200-460 m) [85,88,94,155,156]. Its presence is scattered and isolated above 1,500 feet (460 m), where it generally occurs in chaparral belts on shallow soils [85,88,114].

The percent frequency of California sagebrush-dominated communities at different elevations was measured at 120 sites in southern California. The findings are presented in the table below [118]:

Elevation (% frequency)

Community type 0-500 feet 500-1,000 feet 1,000-1,500 feet 1,500-2,000 feet 2000+ feet Monotypic 0 0 13 19 23 California sagebrush-eastern Mojave buckwheat-white sage 0 18 16 23 23 California sagebrush-coyote bush-basin wildrye 7 12 6 0 8 San Luis purple sage-California sagebrush 25 47 16 0 23 California brittlebush-California sagebrush 21 0 0 3 0

Floodplains: California sagebrush may appear in riparian and floodzones [90,115,181]. Due to the lack of perennial water, several floodplain systems in southern California are composed of unique scrub vegetation rather than the more common riparian woodlands. Of the 10 major floodplain scrub communities, California sagebrush occurs in 4 (San Sevaine, Cucamonga, San Antonio, and San Gabriel). Floodplain scrub vegetation is periodically subjected to severe flooding, erosion, nutrient-poor substrates, and the presence of subsurface moisture. Floodplain scrub communities are found exclusively on the coastal side of major mountain ranges in southern California [90].

Litter: California sagebrush tends to occupy and dominate in sites with a "low" litter mass [202].

Soil: California sagebrush occurs on virtually all soil types, excluding serpentine [42,146]. It has no strong soil type preference, making it the most common species in coastal sage scrub communities [57]. It is the only dominant plant in coastal sage scrub communities that does not exhibit a significant (p<0.01) substrate preference [202]. Soil/substrate types associated with California sagebrush include loam to clayey loams [15,78], sandy loams, and loamy sands. The soils often containing large amounts of gravel, are typically thin and undeveloped, and have little ability to retain nutrients and water [1]. Extensive soil data from a California sagebrush community on Banner Ridge, San Diego County, are presented in a review by Bradbury [29] and from boundary areas between annual grasslands and coastal sage scrub in the review by Hobbs [98].

Transpiration and photosynthesis: In coastal sage scrub communities of the Santa Monica Mountains, California sagebrush has the lowest maximum rate of transpiration and photosynthesis of the dominant plants. The maximum transpiration (g H2O/0.01 m²/hr) and photosynthesis (mg CO2/0.01 m²/hr) rates for California sagebrush in 1968 were 0.67 and 4.02, respectively [93].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

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SAF COVER TYPES [59]:




239 Pinyon-juniper

250 Blue oak-foothills pine

255 California coast live oak

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

ECOSYSTEMS [64]:




FRES28 Western hardwoods

FRES34 Chaparral-mountain shrub

FRES35 Pinyon-juniper

FRES42 Annual grasslands

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

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KUCHLER [119] PLANT ASSOCIATIONS:


K023 Juniper-pinyon woodland

K030 California oakwoods

K033 Chaparral

K035 Coastal sagebrush

K036 Mosaic of K030 and K035

K048 California steppe

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: cover, shrub, woodland

SRM (RANGELAND) COVER TYPES [179]:




201 Blue oak woodland

202 Coast live oak woodland

204 North coastal shrub

205 Coastal sage shrub

206 Chamise chaparral

207 Scrub oak mixed chaparral

208 Ceanothus mixed chaparral

412 Juniper-pinyon woodland

More info for the terms: high-severity fire, shrub

Low-severity fire top-kills California sagebrush [43,118,215]; high-severity fire causes mortality [111,200,216,217]. While the effect of medium-severity fires is not discussed in the literature, Zedler [215] rates California sagebrush mortality from fire as "intermediate" to "high". Shallowly buried seeds are often killed by fire [129,200]; deeply buried seeds survive fire [198].

California sagebrush has a high ratio of dead:live material, making it highly flammable [25]. Shrub species with a high proportion of ether extracts, above 8%, are also considered highly flammable. California sagebrush has a 15.6% level of ether extracts [74,148], characterizing it as "explosively flammable" [148,204].

More info for the terms: cover, forest, shrub, shrubs

The pungent aroma and bitter taste of California sagebrush is unpalatable to livestock and wildlife [176]. DeSimone and Zedler [54] suggest that terpenes contained in the leaves of California sagebrush protect the plant from herbivory. Columbian black-tailed deer browse California sagebrush "limitedly" during the growing season [176]. Historically, feral domestic sheep and goats browsed California sagebrush on south-facing slopes of the Channel Islands [32,141]. In the Los Padres National Forest, domestic goats are used to manage brush regrowth on fuelbreaks. Where California sagebrush occurs, domestic goats generally browse on the shrub year-round [76].

During the dry season in northern Baja California, domestic goats browse California sagebrush and bastardsage (Eriogonum wrightii). Domestic goats feed on California sagebrush during leaf initiation, vegetative growth, flowering, fruiting, and dried leaf stages. Feeding mostly occurs during the dried leaf stage [65].

Small mammals/birds: The California gnatcatcher preferentially forages in California sagebrush and eastern Mojave buckwheat stands, particularly because the shrubs support a high number and variety of arthropods [13,21,146]. Arthropods are more abundant on California sagebrush than on eastern Mojave buckwheat [13].

Dusky-footed and desert woodrats have a high food preference for California sagebrush [136]. Near Irvine, 7 rodent species (4 cricetids and 3 heteromyids) fed regularly on California sagebrush from early winter until early spring [137].

Palatability/nutritional value: Due to the pungent aroma and bitter taste of California sagebrush, palatability of the plant is low [176]. While little browsed, California sagebrush protein content is adequate for livestock production [65].

The crude protein content of California sagebrush at Mesa La Mision, Baja California, during 5 phenological stages is presented below [65]:

Phenological stage Crude protein content (%) Leaf initiation 14.3 Vegetative growth 10.4 Flowering 14.1 Fruiting 6.9 Dry leaves 6.0

The mean (8 samples/month for 24 months) annual nutrient content of California sagebrush in the Santa Monica Mountains is presented below. Plants were from a site 490 feet (150 m) above sea level, 2 miles (3 km) from the ocean, and on a 10% to 15% slope [69,71].

N (%) P (%) K (%) Ca (%) Mg (%) 1.88 0.225 1.42 0.94 0.267

Cover value: As the tallest subshrub in the coastal sage scrub community, California sagebrush is an important cover species for a variety of small birds, mammals, amphibians, and arthropods [30,33,81,104,123,166,190,193]. In a review, Wirtz [211] lists common mammals, amphibians, arthropods, and birds associated with California sagebrush.

California sagebrush provides preferred habitat for Bell's sage sparrow, a bird species endemic to shrubby habitats and state-listed as a Species of Special Concern [3]. At the Motte Rimrock Reserve, successful Bell's sage sparrow nesting sites are associated with areas high in California sagebrush and brittle bush cover [145].

The California gnatcatcher is found almost exclusively in California sagebrush-dominated communities [2,21,146,174]. In southern California, California gnatcatcher nests are most frequently found in California sagebrush stands, followed in order by white sage, black sage, chamise, and prickly-pear (Opuntia ssp.) [13,21].

More info for the terms: codominant, cover, hardwood, xeric

California sagebrush is the most important and widely distributed plant in the
coastal sage scrub or "soft chaparral" community type [41,86,103,117,188,202]. It also
occurs with limited distribution in "hard chaparral" communities dominated or
codominated by chamise (Adenostoma
fasciculatum), bigpod ceanothus (Ceanothus megacarpus), hoaryleaf
ceanothus (C. crassifolius), California scrub oak (Quercus dumosa),
curlleaf mountain-mahogany (Cercocarpus ledifolius), sugar sumac (Rhus ovata),
toyon (Heteromeles arbutifolia), and hollyleaf cherry (Prunus
ilicifolia) [62,70,86,140,188]. In the Great Basin sage scrub community of the San Bernardino Mountains,
California sagebrush is codominant with
rubber rabbitbrush(Chrysothamnus nauseosus) and antelope bitterbrush (Purshia tridentata)
[144]. In plant communities adjacent to coastal sage scrub, overstory
associates of California sagebrush include bigcone Douglas-fir (Pseudotsuga
macrocarpa), Monterey pine (Pinus radiata), bishop pine (P.
muricata), singleleaf pinyon (P. monophylla), California juniper (Juniperus
californica), and Tecate cypress (Cupressus forbesii) [10,26,99,103,134,135,140,150,169,188,194,196].

In 1990 and 1991, Davis and others [51] used satellite imagery, air photos, existing vegetation maps, and
field data to measure vegetation cover for 8,260,000 acres (3,383,160 ha) within the California
Floristic Province. The researchers classified California sagebrush as codominant
over 629,600 acres (254,800 ha), of which 356,749 acres (144,371 ha) is typed as
coastal sage scrub [51].

California sagebrush is listed as a dominant or codominant species in the following
locations and vegetation classifications:

• California sagebrush coastal sage scrub communities [30]

• Xerophytic sites at "lower" elevations on the ocean and
  landward slopes of the Santa Lucia Mountains (monotypic) [180]

• California sagebrush-black sage (Salvia mellifera) in upland communities
  along the Ventura River [49]

• California sagebrush-eastern Mojave buckwheat (Eriogonum fasciculatum) in
  scattered locations found throughout terraces, foothills, and mountains along
  the Ventura River [49]

• California sagebrush-laurel sumac (Malosma laurina) on dry foothills along
  the Ventura River [49]

• Coast live oak (Quercus agrifolia)/California sagebrush/grass (species not defined in
  classification) on middle elevation xeric hardwood rangelands [8]

• California sagebrush and California sagebrush-eastern
  Mojave buckwheat in the coastal sage scrub region of the Liebre Mountains [28]

• White sage (S. apiana)-California sagebrush-California buckwheat,
  California sagebrush-white sage, California sagebrush-common deerweed (Lotus scoparius), and California
  sagebrush-black sage at Starr Ranch in the foothills of the Santa Ana Mountains [53]

• Island ceanothus (Ceanothus megacarpus var. insularis)-California
  sagebrush on south-facing slopes of Islay Island [24]

• California sagebrush-coyote bush (Baccharis pilularis) on southern aspects of Santa Rosa
  Island, Channel Islands National Park [41]

• California sagebrush-white sage-black sage on hillsides facing the coast below 1,500 feet
  (500 m) in the San Gabriel Mountains [86]

• California sagebrush is a codominant species in the alluvial scrub community
  along the Santa Ana River. Other dominant species include eastern Mojave
  buckwheat, chamise, hairy yerba santa (Eriodictyon trichocalyx), common
  deerweed, and sugar sumac [89].

• In the San Bernardino Mountains, California sagebrush is codominant with
  eastern Mojave buckwheat, white sage, and brittle bush (Encelia farinosa) in the eastern
  portion of the San Bernardino Valley [103].

• California sagebrush, California sagebrush-eastern Mojave buckwheat-white sage,
  and California sagebrush-coyote bush-basin wildrye (Leymus condensatus) in coastal sage
  scrub basins between Santa Barbara and Banning [117]

• San Luis purple sage (Salvia leucophylla)-California sagebrush found in the inland
  zone of the coastal sage scrub [117]

• California brittle bush (E. californica)-California sagebrush in low altitude,
  well-insolated sites, mainly in the coastal region [117]

• California sagebrush communities in the San Bernardino Mountains [140]

• California sagebrush-black sage-laurel sumac-eastern
  Mojave buckwheat at Camp Pendleton [150]

• California sagebrush-black sage-white sage in coastal sage scrub communities of Santa Catalina
  and Santa Cruz islands [141]

More info for the term: shrub

Shrub

More info for the terms: cover, forest, fuel, grassland, interference, nonnative species, shrub, shrubs

Fertilization:
Nitrogen fertilization of California sagebrush seedlings caused a significant (p<0.01)
increase in shoot biomass. Soil was amended with nitrogen concentrations of 2
µg/g, 20 µg/g, 40 µg/g, and 80 µg/g. Following 3 months of growth,
California seedling shoots at the 4 treatments had a biomass (oven dried) of
0.07 g, 0.67 g, 0.96 g, and 1.18 g, respectively [163].

Browsing:
Heavy browsing of California sagebrush by
feral domestic sheep on south-facing slopes of Santa Cruz Island has caused the
complete destruction of the plant community [32].
California sagebrush
grows best in areas protected from domestic goats [142].

Growth regulators:
A reduction in California sagebrush growth over a 3-year period occurred following the application of
several growth regulator chemicals (PP333 or EL500). Growth regulators were
applied from 1981 to 1983 to evaluate there use in reducing fuel to prevent wildfires.
In 4 field trials, California sagebrush
height was significantly (p<0.05) reduced by growth regulators [95].

Herbicides:
Glyphosate concentrations from 1.0%
to 2.0% resulted in the death of 90% to 99% of California sagebrush shrubs
1 year following treatment in southern California [105]. California
sagebrush plants can be controlled and/or killed with the herbicides 2,4-D [164].

Loss of range:
Estimates of California sagebrush-dominated habitat vary. Several authors
report that California sagebrush-dominated coastal
sage scrub has lost 66% to 90% of its original vegetation to development,
agriculture, vegetation type conversion, and changing FIRE REGIMES
[5,40,51]. Conversely, Taylor [186], using U.S. Forest Service Vegetation Type Maps,
assessed the loss of California sagebrush dominated and codominated habitat
in southern California from 1931 to 1995. The researcher estimates that 64% of
California sagebrush communities remained undeveloped in 1995, while 59% of
California sagebrush-eastern Mojave buckwheat-chamise plots remained undeveloped in 1995 [186].

Nonnative species:
The invasion of coastal sage scrub communities by
Mediterranean annual grasses may be increasing
[5]. The annual grasses soft chess (Bromus hordeaceus), red brome, ripgut
brome, slender oat (Avena barbata), and wild oat (A. fatua) may depress growth of
young California sagebrush plants. The question
of possible growth interference was evaluated at the Santa Margarita Ecological Reserve near San Diego. In plots
without annual grasses, aboveground biomass of 4-month-old California
sagebrush seedlings was
significantly (p<0.05) greater than in plots with annual grasses. At 16 months
of age, California sagebrush plant biomass remained significantly less in
plots with annual grasses. California sagebrush plants may have had less biomass when cooccurring with
annual grasses due to depletion in available water and sunlight [57]. However,
by the end of the 2nd growing season, the biomass of surviving
California sagebrush plants was similar to that of plants in plots without annual grasses
[56].

Prescription fire is discouraged as a method of controlling
nonnative species in California sagebrush communities. Alternative methods are currently being
researched. From 1999 to 2002, Allen [5] found that control of Mediterranean grasses
was possible via domestic sheep grazing and
grass-specific herbicide application.

Plant facilitation:
California sagebrush has a positive influence on the establishment of blue
oak (Quercus douglasii) seedlings. In Carmel Valley, Monterey County,
blue oak seedlings were significantly (p<0.001) associated with California
sagebrush and San Luis purple sage. While  combined cover of California
sagebrush and San Luis purple sage was 37% at the study site, 91% of all blue oak seedlings
were located under the canopies of the 2 shrubs. Shade provided by the shrub
canopy promotes blue oak seedling
establishment [35].

In the San Ynez Valley and San Ynez Mountains, California sagebrush and San Luis
purple sage have a positive influence on coast live oak (Q. agrifolia)
seedlings. At the 2 study sites, coast live oak seedlings were significantly
(p<0.001) associated with California sagebrush and San Luis purple sage.
Combined cover of the 2 shrubs at the 2 sites was 36% and 27% on San Ynez Valley
and San Ynez Mountain plots, respectively, However, 80% and 68% of all coast live oak seedlings
on San Ynez Valley and San Ynez Mountain plots, respectively, were found under the canopies of
California sagebrush and San Luis purple sage. At these 2 sites, shade provided by canopy cover
was not the only contributing factor for coast live oak establishment and
survivorship. Significantly (p<0.05) fewer coast live oak seedlings growing under the shrub canopies were browsed by
livestock, mule deer, and California pocket gophers compared to
seedlings growing in open grassland or under the canopy of adult coast live oak
trees. The percentages of seedlings browsed under the canopies of California
sagebrush and San Luis purple sage were
7.7 ± 14.0 (mean ± SD)
and 8.7 ± 14.7, respectively, in open grasslands and 52.9 ± 32.2 and 50.0 ± 35.9, respectively, under coast
live oak [36]. A similar study by Callaway
and Davis [38], conducted in Gaviota State Park, evaluates the
importance of shrubs (including California sagebrush) in the recruitment of coast live oak
seedlings.

Soil amendments:
On disturbed land on the Santa Margarita Ecological Reserve, soil was amended with a slowly
decaying amendment (pine bark) and a rapidly decaying amendment (oat straw)
prior to the planting of 2-inch (5 cm) California sagebrush seedlings. The
survival rate of California sagebrush seedlings 28 months after planting was
~25% in the pine bark, ~16% in oat straw, and ~15% in the control. Plant volume
28 months after planting in pine bark, oat straw, and control treatments was
~275,000 cm³, ~125,000 cm³,
and 100,000 cm³, respectively [218].

More info for the term: fresh

California sagebrush is used as an ornamental [31] and has an extensive history as a plant of importance for Native Americans [146], miners [48], and Spanish [48] and Mexican settlers [79]. The pollen of California sagebrush is extracted and used as a desensitizing agent for the relief of hay fever [79].

California sagebrush is considered 1 of the most important medicinal plants by Cahuilla Native Americans in southern California. It was used to induce menstruation, provide a comfortable child-birth experience, and promote rapid postnatal recovery. Beginning with the onset of menstruation, young girls were given a tea made from boiled California sagebrush. From this point forward, California sagebrush tea was drunk just prior to each menstrual period for the duration of their reproductive life. The drink was given to newborn babies 1 day after birth to clean out their system [19,146]. The leaves of California sagebrush were also used by Cahuilla Native Americans to relieve colds, chewed fresh or dried, and were smoked after mixing with tobacco and other leaves. California sagebrush was also used in Cahuilla sweathouses for various cures [19,146].

The Chumash Native Americans of southern California had many uses for California sagebrush. The branches were used as firesticks, arrow foreshafts, and brush windbreaks and enclosures. California sagebrush was processed into a poultice and applied directly to the forehead to relieve headaches. The Chumash would soak California sagebrush leaves in water and bath in it or use it as a ritualistic purification sprinkling agent, particularly related to death. Bundles of branches were also erected along paths to shrines [189].

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More info for the term: fruit

California sagebrush initiates new leaf growth with the onset of the 1st significant rainfall. Flower development, branch elongation, and fruit production do not begin for several months after leaf growth begins, with some variation among years and habitats [56,57,63,68,146]. California sagebrush foliage is lush and green, and growth is continuous during rainy periods in winter and spring [42,146,150]. From summer until the onset of winter rains, the large leaves that are produced during the rainy season are dropped, and smaller leaves emerge in late spring and are retained during the dry season [57,63,93,199,203]. Leaf shedding allows California sagebrush to avoid long-term water stress [54,146]. California sagebrush generally shows substantial leaf biomass production within 2 weeks following the end of drought season [170]. Under severe drought conditions, California sagebrush stems become bare and die back [30,93]. California sagebrush shows no measurable aboveground growth for the 2 to 4 driest months of the year [68]. Various flowering times for California sagebrush have been reported; depending upon elevation and geographical location, they include September and October [72], August to December [155,156], November to mid-May [150], year-round [48], and April to October and April to June in Baja California [65,210].

The approximate phenological development of California sagebrush at Mesa La Misión, Baja California, Mexico, is as follows [65]:

Phenological stage Time period Vegetative growth January to April Flowering April to June Fruiting June to August Dried leaves August to December

More info for the terms: fire severity, high-severity fire, root crown, seed, severity

California sagebrush establishes after fire by seed [62,78,108,109,110,146,177,200,201,204] and sprouting from the root crown [45,78,78,125,126,127,128,129,130,200,201]. Root crown sprouting is the primary postfire regeneration method, occurring in the 1st year after fire. California sagebrush seedling emergence after fire is considered "variable" and generally "low" [146,204]. Seed production does not usually take place on burn sites until after the sprouts have flowered and set seed, in postfire year 2 at the earliest [108,204]. However, seedling establishment on burned sites in the 1st postfire year may occur from soil-stored seed [108,198] not killed by high-severity fire [129,200] or seeds dispersed onto the burned site by wind [54,56,57,141,146,150] or animal activity [56,57]. Sprouting California sagebrush plants flower vigorously the 1st few years after burning [160,214]. Sprouting tends to be less in burn areas composed of dense vegetation, where California sagebrush plants are older, or where fire severity was high [146]. Westman and others [200] note that coastal California sagebrush plants tend to recover after fire more quickly than inland plants. California sagebrush coastal populations experience greater precipitation and more temperate conditions than do inland plants, creating more suitable conditions for recovery following fire [40,84,93].

More info for the terms: adventitious, ground residual colonizer, secondary colonizer, seed, shrub

POSTFIRE REGENERATION STRATEGY [184]:
Small shrub, adventitious bud/root crown
Ground residual colonizer (on-site, initial community)
Secondary colonizer (on-site or off-site seed sources)

More info for the terms: allelopathy, charate, cover, density, dispersion, grassland, natural, perfect, prescribed fire, root crown, seed, shrub, shrubs

California sagebrush regenerates by seed [54,56,57,111,141,146,150,152] and sprouting from the root crown [45,70,78,108,125,126,127,128,146,204] following disturbances such as fire (see Plant Response to Fire).

Pollination: California sagebrush is wind pollinated [146].

Breeding system: California sagebrush has perfect flowers [60,210].

Seed production: California sagebrush plants produce an "abundant" number of seeds annually. In southeastern Orange County, the average seed production of individual California sagebrush shrubs is usually greatest on south-facing slopes. DeSimone and Zedler [54] sampled the seed production of 16 California sagebrush plants on north- and south-facing slopes from February 1995 to May 1996, and sampled on south-facing slopes from fall 1996 to winter 1997. The average seed production per shrub (no. of seeds ± SD) on north-facing slopes from February 1995 to May 1996 was 21,357 ± 11,163, compared to 43,638 ± 19,671 on south-facing slopes. Seed production on south-facing sites from fall 1996 to winter 1997 was 38,228 ± 9,012.

Seed dispersal: California sagebrush seeds are primarily wind dispersed [54,56,57,141,146,150]. Animal dispersion is noted in the literature as a secondary method of dispersal [56,57]. The seeds of California sagebrush are primarily dispersed during autumn [108]. In southeastern Orange County, the dispersal of California sagebrush seeds in an annual grassland, an ecotone (10%-20% shrub cover), and a coastal sage scrub community was measured from February 1995 to May 1996. Seed counts were taken on both north- and south-facing slopes. In the grassland, California sagebrush seeds were dispersed at maximum 15 feet (5 m) from the isolated shrubs. In total, most seeds were found on south-facing slopes, though seed numbers were similar in coastal sage scrub. The following table provides California sagebrush seed counts (no. of seeds ± SD) for north- and south-facing slopes in the 3 communities [54]:

Aspect Grassland* (n = 10) Ecotone (n = 4) Coastal sage scrub (n = 4) North-facing 69 ± 61 284 ± 74 734 ± 75 South-facing 849 ± 435 1,103 ± 357 730± 224 *Contained isolated California sagebrush plants

Seed banking: California sagebrush utilizes a seed bank [198]. As of 2006, the literature did not describe the longevity of California sagebrush seeds in the seed bank. Due to the "steady" germination of soil-stored seeds, California sagebrush often fails to develop a seed bank adequate for the recruitment of large numbers of seedlings during the 1st postdisturbance growing season (review by [108]).

In southeastern Orange County, germinable soil seed bank densities of California sagebrush were measured in spring 1995 and 1996 on north- and south-facing slopes of grassland, ecotone, and coastal sage scrub communities. The following table provides California sagebrush germinable soil seed bank densities (no. of seeds ± SD) for north- and south-facing slopes in the 3 communities [54]:

Aspect Grassland (n = 10) Ecotone (n = 4) Coastal sage scrub (n = 10) North-facing 58 ± 31 50 ± 19 222 ± 72 South-facing 42 ± 30 200 ± 98 584 ± 208

Germination: California sagebrush seed germination is induced by several factors. Light, charate, or heat and charate can break seed dormancy [17,54,56,57,108,109,110,146,161]. Seeds near the soil surface may germinate readily with the addition of adequate moisture that occurs with the onset of fall and winter rains [17,54,56,57,110,146]. Seed germination is also favored by cool soil temperatures [56,57] and a day/night temperature regime of approximately 70 °F/40 °F (20 °C/6 °C) [17,198]. Keeley [108] showed the rate of germination by seeds is also influenced by heat and charate (see below).

Fire-induced germination: Seeds can be stimulated to germinate by heat and/or chamise charate [17,108,109,110,161]. Two studies on the effects of heat and charate on California sagebrush seeds buried in the soil at and below light penetration level are presented below.

Keeley [108] investigated the effect light, darkness, temperature, and charate have on California sagebrush seed germination. Germination trials were conducted on filter paper and in soil. California sagebrush seeds germinated significantly (p<0.001) better in the soil treatment, and the following results are from the seeds germinated in soil. Temperature treatments were a control, 158 °F (70 °C) for 1 hour; 212 °F (100 °C) for 5 minutes; and 248 °F (120 °C) for 5 minutes. One set of seeds received a 0.50g application of chamise charate prior to temperature treatments. Following charate and temperature treatments, the seeds were stratified for 1 month at 41 °F (5 °C) and then incubated in the light or dark treatment for 3 weeks at 73 °F (23 °C). Both light and charate had a significant (p<0.05) positive effect on the germination of California sagebrush seeds. Seeds with charate application and subjected to light germinated significantly (p<0.05) better than treatment seeds subjected to only darkness. Seeds subjected to darkness and charate treatment germinated significantly (p<0.05) better than seeds subjected to only darkness. Within the light treatment, the only significant (p<0.05) difference was the germination rate of charated seeds subjected to the 212 °F (100 °C) for 5 minutes treatment (81%) and noncharated seeds subjected to the same temperature treatment. When assessing the effect temperature alone has on germination, there was no significance found. Greater than 75% of the California sagebrush seeds germination occurred by the 1st week of the 73 °F (23 °C) incubation period (reviews by [108,109,110]).

Treatment Percentage germination Light Dark Control 158 °F
(1 hour) °F
(5 min) 248 °F
(5 min) Control 158 °F
(1 hour) 212 °F
(5 min) 248 °F
(5 min) Control 73 56 47 56 0 10 3 0 Charate 78 80 81 87 62 49 64 50

Seed banked California sagebrush seeds that were subjected to artificial fire conditions produced substantially more germinants than seeds exposed to prescribed fire in the field. California sagebrush seeds obtained from a prefire soil seed bank in a chamise-dominated chaparral community in central California during fall 1989 were treated with heat (212 °F (100 °C) for 5 minutes) and charate (2 tablespoons of charred chamise/pot) and germinated in a greenhouse. The heat and charate treatment produced a mean of 259.6 California sagebrush germinants/m². Shortly after seeds were collected for the preceding experiment, the site was burned for the 1st time in approximately 50 years. The day after the fire, the researcher collected seeds from the seed bank and planted them in a greenhouse with no further treatment. The rate of germination in the greenhouse (4.4 germinants/m²) far exceeded natural seed germination in the field (0.04 germinant/m²) following fire but was less than germination from seeds treated with heat and charate [161].

Seedling establishment/growth: California sagebrush seedlings emerge during the rainy season (November-April), and most growth is completed by May with the onset of the dry season [146]. Seedling cover increases for a time after the growth and flowering of young plants. As California sagebrush stands mature and the canopy closes, seedling establishment becomes "poor" [154]. California sagebrush seedlings suffer high rates of mortality due to small animal herbivory [146] and may suffer mortality or inhibited growth due to California sagebrush allelopathy [154]. In areas invaded by annual grasses, California sagebrush seedlings are "outcompeted" for soil moisture, and the rate of survival in their 1st year is "very" low [54]. California sagebrush seedling emergence after fire is "variable" and generally "low". California sagebrush seedlings commonly appear during postfire year 2 from seeds of sprouting plants or seeds dispersed on-site [146,204].

California sagebrush seedling recruitment appears to occur in gaps without fire. In southeastern Orange County, California sagebrush seedling density in 3 communities (annual grassland, ecotone, and coastal sage scrub), on 3 aspects (south-, north-, and west-facing), and in vegetation gaps and under vegetation were measured to assess seedling recruitment between fires. Seedling measurements occurred during March 1995 and 1996 on sites fire-free for 17 years. In the 3 communities and 3 aspects, California sagebrush seedling density was greatest in vegetation gaps. California sagebrush seedlings were significantly (p<0.001) associated with gaps in mature vegetation in coastal sagebrush communities. Vegetation gaps in grasslands were pocket gopher mounds, gaps in ecotones were bare areas between perennial grasses, and gaps in scrub were areas devoid of shrub canopy. California sagebrush seedling density (no. of seedlings/m²) on the various sites is presented below [54]:

Community South-facing North-facing West-facing Gaps Under vegetation Gaps Under vegetation Gaps Under vegetation Grassland 0.20 0.01 0 0 0 0 Ecotone 5.47 3.12 0 0 0.59 0 Coastal sage scrub 6.60 2.98 0.74 0.11 1.05 0.68

As further evidence that California sagebrush recruitment takes place between fires, juvenile (<20 inches (50 cm) in height and nonreproductive) shrubs were found in all 3 communities and aspects. Recruitment was greatest on west-facing slopes. The density (no. of juveniles/m²) of juvenile California sagebrush shrubs is presented below [54]:

Community South-facing North-facing West-facing Grassland 0.05 0.04 0.42 Ecotone 0.24 0.66 1.47 Scrub 0.36 0.04 1.23

In the coastal sage scrub and grassland communities, California sagebrush seedling growth was measured at the end of May in 1995 and 1996 on south-facing slopes in coastal sage scrub and annual grassland sites. The rate of growth of California sagebrush seedlings in the grassland community was much greater than growth in the coastal sage scrub community. The height (cm ± SD) of California sagebrush seedlings in the 2 sites is presented below [54]:

Site 1995 1996 Coastal sage scrub 3.71 ± 2.69 5.00 ± 3.06 Grassland 18.67± 2.08 44.00 ± 7.94

California sagebrush density can depend on winter precipitation. On 16 September 1935 a fire burned in Frankish Canyon at the western edge of San Bernardino County. The number of California sagebrush seedlings/milacre surviving after fire and their average height were measured 8 times over a 17-year period following the fire. The researchers attribute the high number of California sagebrush plants/milacre in postfire year 17 to above normal precipitation during the winter of 1951 to 1952 [101].

  Years after fire 1 2 3 4 5 7 10 17 Surviving
seedlings/milacre 3.2 2.2 2.0 2.2 2.0 4.9 4.1 14.8 Average height (inches) 2.7 9.1 16.3 19.3 21.1 24.1 29.9 ----

Vegetative regeneration: Following damage to aboveground portions of the plant, California sagebrush sprouts from the root crown. Vegetative sprouting is the most common regeneration method following fire [45,70,78,108,125,126,127,146,204]. To study vegetative regeneration of California sagebrush in the absence of fire, Malanson and Westman [130] cut 50 mature California sagebrush shrubs to ground level in the Santa Monica Mountains on a site unburned for 11 years. Two years after cutting, 80% of the shrubs had sprouted [130].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

BLM PHYSIOGRAPHIC REGIONS [20]:




3 Southern Pacific Border

(key to state/province abbreviations)
UNITED STATES CA
MEXICO B.C.N.

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More info for the terms: association, competition, cover, density, forbs, forest, grassland, herbaceous, natural, seed, shrub, shrubs, succession, woodland, xeric

California sagebrush is adapted to disturbed sites [61,215], is shade intolerant [54,54,61], and occurs across the successional gradient [90]. It is a pioneer species [34,61] in primary and secondary succession and persists as a dominant species through late seral stages in coastal sage scrub communities [18,36,44,90,138,215]. Hall and Clements [79] describe California sagebrush as typically a late successional dominant, but often seral to the chaparral association. This likely occurs in the higher elevation chaparral belt where California sagebrush is a postdisturbance colonizer on steep and/or rocky xeric sites [175]. Disturbances common at these sites include long-term overgrazing or changes in historic FIRE REGIMES [195].

Researchers have suggested that various successional progressions where California sagebrush and other dominant coastal sage scrub species occur are influenced by dynamic community boundaries, intervals between fires and other disturbances, and competition between species for environmental resources following disturbance [5,71]. The following section presents research on the effect different disturbance mechanisms have on coastal sage scrub succession.

Anthropogenic disturbance: Within 2 years following the construction of an oil pipeline in the Purisima Hills, Santa Barbara County, California sagebrush had naturally reestablished on the right-of-way. Two years after initiation of growth, shrubs were from 12 to 22 inches (30-55 cm) tall and 14 to 20 inches (35-50 cm) in diameter [36].

In 1985, California sagebrush, along with white sage, black sage, eastern Mojave buckwheat, and brittle bush were outplanted on unamended soil (Arlington loam) in a native plant garden at the Forest Fire Laboratory in Riverside. Inadvertently, the aboveground biomass of the plants was mechanically removed in 1991. Four years later, California sagebrush had regenerated. The density, relative cover, and biomass of California sagebrush in October 1995 were 8.04/m², 68.5%, and 238 g/m², respectively. Given that no coastal sage scrub parcels were in close proximity to the mechanically cleared plots, reestablishment was from on-site seed and root crown sprouting [158].

In San Diego County, severe disturbance (construction, landfill operations, heavy-vehicle activity, tillage, and soil excavation) caused the near extirpation of California sagebrush and other coastal sage scrub species, replacing them with the herbaceous species rattail fescue, brome (Bromus spp.), oatgrass (Danthonia spp.), longbeak stork's bill (Erodium botrys), and smooth catsear (Hypochaeris glabra). While California sagebrush, white sage, chamise, and eastern Mojave buckwheat were the most abundant shrub species on undisturbed sites, these shrub species combined never made up more than 5% of total cover, even when nearby seed sources were available, on sites disturbed 1 to 43 years prior to the study [185].

Community transition: Frequent disturbance in coastal sage scrub communities has strong influence on community structure and transition. Keeley and Keeley [114] hypothesize that recurrent disturbance in coastal sage scrub communities facilitates successional replacement by annual grasslands. Horton [100] suggests that in the absence of disturbance, coastal sage scrub is replaced by coast live oak. Utilizing aerial photography, Callaway and Davis [37] measured transition rates among annual grassland, coastal sage scrub (codominated by California sagebrush), chaparral, and coast live oak woodland communities in Gaviota State Park from 1947 to 1989. In unburned and ungrazed plots, a transition from grassland to coastal sage scrub occurred at a rate of 0.69%/year, from coastal sage scrub to coast live oak woodland at a rate of 0.30%/year, and from coastal sage scrub to chaparral at a rate of 0.11%/year.

Fire: California sagebrush is adapted to burned sites and is an early successional species following fire [18,47,61,85,143,182]. Recovery of coastal sage scrub species from fires that occur at natural, decades-long intervals is rapid. During postfire years 1 and 2, a flush of native annual forbs (sometimes mixed with exotic grasses and forbs) is common, followed by recovery of native shrubs via the seed bank, off-site seed sources, sprouting, and seeds produced by the sprouting shrubs [6,127].

Whereas most California sagebrush regeneration following fire is primarily via sprouting [108,160,204] and relatively rapid, Myers and Ellestrand [157] found that postfire growth at an inland sage scrub site (Motte Rimrock Reserve, Riverside County) was via seedlings and delayed. At the end of postfire year 2, sage scrub (California sagebrush, eastern Mojave buckwheat, brittle bush, and black sage) cover was only 4% of cover on adjacent unburned sites. By the end of postfire year 4, shrub cover was roughly 50% of cover on unburned sites.

California sagebrush seedlings are also pervasive in recently burned chaparral sites but become absent as the stands mature [50,87]. Several studies in the Santa Monica and San Gabriel mountains have found that California sagebrush establishes in chaparral following fire, but over time it is replaced by species that were dominant before fire [71,86,101,103]. At the boundary between chamise chaparral and coastal sage scrub communities (around 3,000 feet (900 m) elevation), a dynamic relationship occurs when fire frequencies are increased. Following fire disturbances in chamise chaparral, coastal sage scrub species often invade the site. The resulting vegetation mosaic is often called the coastal sage-chaparral "subclimax". Species diversity in the coastal sage-chaparral "subclimax" community is often low and common species include eastern Mojave buckwheat, California sagebrush, white sage, black sage, golden-yarrow (Eriophyllum confertiflorum), cudweed (Gnaphalium spp.), and sawtooth bristleweed (Hazardia squarrosa var. grindelioides) [87,88]. (For further information, see Plant Response to Fire.)

Nitrogen deposition: California sagebrush populations have been declining over the past 60 years or more in coastal sage scrub vegetation of southern California. California sagebrush is steadily being displaced by Mediterranean annual grasses [40]. One possible factor contributing to the decline in California sagebrush density is nitrogen deposition [5,9]. Approximately 45 kg/ha/yr of nitrogen is deposited in coastal sage scrub communities from the Los Angeles Air Basin. As much as 87 kg/ha/yr of nitrogen deposition has been recorded in coastal sage scrub near the urban areas [5,9]. In controlled trials, red brome (Bromus rubens) and rattail fescue overwhelmingly "outcompeted" California sagebrush plants when subjected to elevated levels of nitrogen [6,7,9].

Artemisia californica var. californica Munz [155,156]

The currently accepted scientific name of California sagebrush is Artemisia californica
Less. (Asteraceae) [60,94,107,210].

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California sagebrush seeds and transplants have been used successfully in the rehabilitation of disturbed sites [27,33,40,46,67,91,96,97,106,165,197]. Further, California sagebrush is described as a shrub that has erosion control potential [34,102,147].

Crossostephium foliosum (Nutt.) Rydberg
? Artemisia Fisheriana vegelior Besser, Nouv. M6m. Soc. Nat. Mose. 3: 88. 1834. Artemisia foliosa Nutt. Trans. Am. Phil. Soc. II. 7: 397. 1841.
A shrub 1-2 m. high; branches densely canescent; leaves 2-4 cm. long, densely cauescent, the upper filiform, less than 0.5 mm. broad, revolute, the lower 3-fid above the middle; heads numerous, in leafy raceme-like panicles; involucre hemispheric, about 3 mm. high, 4-5 mm. broad; bracts 12-15, the outer ones elliptic, canescent, scarcely scarious-raargined, the inner ones oval, less pubescent, and with broad scarious margins; ray-flowers 7-10; corollas cylindric, somewhat flattened, 3-4-lobed; disk-flowers 15-20; corollas cylindro-campanulate, 5-toothed, 1.5 mm. long; achenes 3-5-ribbed, becoming glutinous in wetting; pappus coroniform.
Type locality: Monterey, California. Distribution: California and adjacent islands.

Crossostephium californicum (Less.) Rydberg
Artemisia californica Less. Linnaea 6: 523. 1831.
Artemisia Pischeriana Besser, Nouv. M4m. Soc. Nat. Mose. 3: 21. 1834.
ArUmisia abrotanoides Nutt. Trans. Am. Phil. Soc. II. 7: 399. 1841.
A shrub 1-3 ra. high; branches grayish-strigose; leaves 2-5 cm. long, fascicled, pinnately divided into filiform divisions or the upper entire and filiform, revolute, canescent, fleshy; beads numerous, nodding, in dense panicles with racemiform branches; peduncles 1-5 mm. long; involucre depressed-hemispheric, 3 cm. high, 5-6 mm. broad; bracts 15-20, in about 3 series, somewhat canescent, the outermost oblong, fleshy, somewhat shorter, the inner ones with thick backs and broad scarious margins, obovate or rounded-spatulate; rayflowers 8-10; corollas cylindric, short, regular, 4-loothed, glandular-granuliferous; diskflowers 15-20; corollas campanulate, 5-toothed, 2 mm. long; achenes 3-5-ribbed; pappus denUte.
Tvpp, f/JCALiTY: California.
Distribution: Central and southern California, along the coast.

Artemisia californica, also known as California sagebrush, is a species of western North American shrub in the sunflower family.