• GENERAL BOTANICAL CHARACTERISTICS
• RAUNKIAER LIFE FORM
• REGENERATION PROCESSES
• SITE CHARACTERISTICS
• SUCCESSIONAL STATUS
• SEASONAL DEVELOPMENT

GENERAL BOTANICAL CHARACTERISTICS:

Redstem ceanothus is a deciduous, shade-intolerant, open erect shrub that grows 3 to 10 feet (1-3 m) in height [43,64]. It is native to North America [92]. Redstem ceanothus has an adventitious root crown with growing points near the ground surface [,103]. The seed of redstem ceanothus is approximately 0.08 inch (2.03 mm) long [41,54].

An important characteristic of most, probably all, ceanothus species is their potential ability to fix large amounts of nitrogen via symbiotic association with root-inhabiting actinomycetes [8,12,16,18]. Nitrogen fixation by ceanothus shrubs may comprise the dominant nitrogen input to some northwest forest ecosystems, especially during secondary or postfire succession [9,12,24]. Please refer also to the Value and Use section of this report for further information.

RAUNKIAER LIFE FORM:

Phanerophyte

REGENERATION PROCESSES:

Redstem ceanothus primarily reproduces through seed, although vegetative regeneration can occur following fire and other disturbance [101,103].

Seed and germination: Most species of ceanothus are prolific seed producers, though annual variation has been noted, and sprouts can produce at least some seed by 3 to 6 years of age [16]. Redstem ceanothus seeds have both water-impermeable seedcoats and dormant embryos that inhibit germination [13,27,33,41,54,83,95]. Relatively high temperatures may be required [95,111], with germination occurring after exposure to temperatures of 185 to 212 degrees Fahrenheit (85-100^oC) [83,95]. Heat followed by stratification improves germination [13,33,90,95]. Rodents, birds, and insects can damage or consume up to 99% of the annual seed crop [16,27]. An Idaho study of redstem ceanothus seeds found that insect damage to seeds accounted for a loss of 9% to 27% of seeds in fruits from 1975 to 1977.

Seed banking: Seed banking is of primary importance in redstem ceanothus [54,55,63,77,103]. Large numbers of seed may remain dormant for decades while stored in the soil or duff [27,55]. Logging and fire create conditions favorable for germination, and numerous seeds germinate simultaneously, even where parent plants are no longer present. Kramer [54] reported viable seed densities ranging from 1.9 to 107 per square foot (21-1155/m²) in central Idaho, and Morgan and Neuenschwander [77] observed seed densities of 0.92 per square foot (10/m²) in uncut stands within western redcedar/queencup beadlily (Clintonia uniflora) habitat types of northern Idaho.

Seed dispersal: Ripe seeds of redstem ceanothus are propelled a short distance away from the parent plant as capsules mature and break apart [54]. Rodents, birds, and ants may also disperse some seed, primarily locally [16].

Seedling establishment: Most seedlings emerge within 1 year after disturbance, although small amounts of seed continue to germinate for up to 8 years [86]. Following fire in northern Idaho, 96% of all seedlings emerged during the 1st growing season, with emergence decreasing over the next 3 years [86]. Later seedlings presumably respond to increased heat absorption by the exposed soil rather than the initial heat generated by fire. Germination of redstem ceanothus is usually poor after mechanical scarification [89], but scattered individuals commonly establish after logging in Douglas-fir forests of the western Cascades [35].

Although plants develop rapidly from seed [100], early mortality is often high [16]. Seedlings are vulnerable to damage by insects, heavy winter ungulate and rodent use, drought, fungus, and competition [27,86,89]. Seedling survival appears to be related to aspect and other site characteristics, climatic factors, and the season and intensity of disturbance [16,86]. Most seedling losses occur the 1st year after emergence [86], with many succumbing to August droughts [5]. Those that are still alive by the 2nd growing season generally survive. In northern Idaho, 30.2% of all redstem ceanothus seedlings survived the 1st summer but only 3.4% remained alive by the 2nd growing season. In another Idaho study, only 9% of all seedlings that survived the 1st summer actually established [86]. Stand densities generally level off by 5 to 6 years of age [16].

Early growth of redstem ceanothus is often rapid. Twigs have reportedly grown as much as 48 inches (122 cm) in a single growing season in the Selway drainage of northern Idaho [111]. Growth slows as plants age, with annual twig growth of older stands (32-36 years) averaging 9.3 to 12 inches (23.6-30.5 cm) [16]. Redstem ceanothus may be killed by late-season frosts, particularly on south slopes, or by extreme winter temperatures [29,69,114].

Vegetative regeneration: Redstem ceanothus often sprouts after the root crown is damaged [53,68,83]. Both root crown sprouting [42,62,100] and upper stem sprouting [109] have been reported after fire. Apical dominance plays an important role in determining the location and extent of sprouting. Dormant buds on the root crown sprout after aboveground vegetation is completely removed. Where portions of the upper stem remain intact, stems commonly resprout. Sprouting is related to age and vigor of the parent plant and may be much reduced beneath a dense tree canopy [42].

SITE CHARACTERISTICS:

Redstem ceanothus grows best on relatively moist slopes in the open or in partial shade [106] and is often most prominent at mid-slope [80]. It is reported at 2,400 feet (732 m) in western Montana [21]. It is reported at 4,000 feet (1200 m) in northern California [43]. Soils are often low in organics (2.0 to 2.5%) [80]. Redstem ceanothus is a prominent component of talus communities within the western hemlock zone of Washington and Oregon [26].

SUCCESSIONAL STATUS:

Redstem ceanothus is associated with early- or mid-seral stages of forest succession [14,16,35,96,120]. In a study of western Montana habitat types, Arno and others [4] list the redstem ceanothus-ninebark community as a seral "structural stage" in postfire successional sequences in Douglas-fir climax forests. Redstem ceanothus is a prominent colonizer after fire [4,50,80,96,100,112,113].

Redstem ceanothus plays a prominent role in dense brushfields that develop throughout its range after fire or timber harvest and subsequent burns [15,45,48,49,112]. It is less shade tolerant than many other brushfield species [45] and disappears as tree canopy cover increases. Mueggler [80] determined that redstem ceanothus cover was positively correlated with years since disturbance, until the development of overstory tree canopy, when it began declining. As tree canopy cover reached 56 to 100%, the shrub disappeared. In the absence of subsequent disturbances, redstem ceanothus may be replaced by oceanspray and chokecherry (Prunus virginiana) [16].

Western redcedar-western hemlock: Redstem ceanothus is prevalent in initial shrub stages in western redcedar-western hemlock habitat types of northern Idaho [100] and in western hemlock-Douglas-fir forests of Oregon's western Cascades [96]. This shrub is a particularly important early seral species in western redcedar/pachistima and western redcedar/queencup beadlily habitat types of northern Idaho [77,78], where it can dominate a nearly closed shrub canopy within 3 to 5 years after high-severity burns [78]. Cover subsequently declines through year 15 as the overstory develops and shade levels increase [78]. In western hemlock-Douglas-fir forests of Oregon, maximum cover is generally attained within 15 years after timber harvests which are followed by broadcast burns [96]. Shrubs such as redstem ceanothus may dominate seral brushfields in western redcedar-western hemlock types for 25 to 50 years but are generally lacking in adjacent undisturbed stands [77,78].

Grand fir: Redstem ceanothus is generally absent in mature grand fir forests of northwestern Montana although common on nearby disturbed sites with a history of logging and/or burning [1,2]. On a western Montana site, no redstem ceanothus was present in mature, uncut sites, while clearcut and burned sites 7 to 16 years old had 8% redstem ceanothus cover. In these sites the logging slash was piled by bulldozer and burned [1]. Redstem ceanothus established as early as the 1st year after fires in grand fir/pachistima habitat types of north-central Idaho [78,118] and dominated some sites by the 3rd to 14th year after logging and burning [112]. Redstem ceanothus, along with snowbrush ceanothus, dominated the understory by year 12 in clearcut and broadcast-burned grand fir/pachistima habitat types of Idaho [117].

Douglas-fir: Redstem ceanothus is a prominent early successional component in Douglas-fir forests west of the Cascades and in parts of the northern Rocky Mountains, especially after wildfire or logging and burning [4,14,16,35,36,50,74,99]. In Oregon Douglas-fir forests a dense shrub layer including redstem ceanothus began forming by the 3rd growing season following logging without burning [46]. Redstem ceanothus and other tall shrubs dominated burned areas in Douglas-fir forests of northwestern Montana for 6 to 10 years but then declined as conifer cover developed [28]. Ceanothus species may slow succession by forming brushfields [16]. (Refer to Management Considerations in the Value and Use section of this report for more information.) In Douglas-fir forests of southern Idaho, redstem ceanothus may dominate certain sites for as long as 25 years [61].

Cholewa and Johnson [14] studied Douglas-fir/ninebark communities in northern Idaho that had been undisturbed since 1900, when they were logged and/or burned. Burning or logging followed by burning led to a higher percent cover of redstem ceanothus than logging alone, which led to a higher percent cover of oceanspray.

Mixed conifers: In mixed-conifer forests of northeastern Oregon, redstem and snowbrush ceanothus can dominate clearcuts within 14 years after initial disturbance but typically begin to decline by year 20 [57].

SEASONAL DEVELOPMENT:

Throughout most of its range, redstem ceanothus flowers from April through June and produces fruit by June or July [81,87,92]. Annual variation in phenological development has been reported. Dates for phenological events in northern Idaho are shown here [87]:

Phenological                      Year
event
                 1971             1972             1973
                 starts  ends     starts  ends     starts  ends 

bud swelling     ----    4/27     4/19    5/6      4/3     4/23
leafing out      5/4     5/26     5/12    6/2      5/2     6/4
stem elongation  5/11    7/8      5/19    8/12     5/16    6/26
flowering        5/19    6/2      5/27    6/13     5/16    6/4
fruiting         6/9     7/27     6/13    8/1      6/4     8/3

Related categories for SPECIES: Ceanothus sanguineus | Redstem Ceanothus