Botanical description: This description covers characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (for example, [97,99,117,193]). Morris and others [161] provide a key for identifying oceanspray and other shrubs in winter. Oceanspray and rockspirea are distinguished by their forms, leaf characteristics, and distributions [136]; intergradation of the 2 species is most pronounced in Nevada [104] and Utah [236].
Photo © 2009 Barry BrecklingMorphology:
Form: Oceanspray is a deciduous [1,41,198], spreading shrub with slender arching branches [75,136,223]. It can range from bushy forms about 2.5 feet (0.75 m) tall on poor or frequently disturbed sites to arborescent forms that may be 20 feet (6.1 m) tall in coastal areas. Plants are usually 3 to 10 feet (1-3 m) in height [52,99,198]. They typically have multiple branches [198]. Stem wood is hard and dense [73]; bark of mature plants is shreddy [41,174]. Stand structures of plant communities where oceanspray is important are discussed in the Stand structure section of Fuels.
Leaves and flowers: The leaves are mostly 1.6 to 2.75 inches (4-7 cm) long and 0.8 to 2.75 inches (2-7 cm) wide [136,223]. Oceanspray has a large leaf area relative to most associated shrubs. In the Siskiyou Mountains of southwestern Oregon, its leaves were more densely packed, larger, thinner, and more prone to wilt than leaves of associated shrub species [40].
Oceanspray flowers are small, about 2 mm long [163]. They are borne on large, showy, terminal panicles that may reach 12 inches (30 cm) long [22]. The name "oceanspray" is derived from these masses of loose, creamy plumes [50]. The fruit is a 1-seeded [45] achene [41,97,117], about 2 mm long [198].
Roots: Rooting depth is likely associated with depth to bedrock. In southwestern Oregon, oceanspray extracted water from no deeper than 3 feet (1 m) below ground, indicating a shallow root system [40]. Dyrness and Franklin [57] had similar findings in the west-central portion of the Cascade Range in Oregon, where shallow soils confined roots to <3 feet below the soil surface. However, a planting guide for the Pacific Northwest reports oceanspray roots as "deep and wide" [154], and researchers described oceanspray as "relatively deep-rooted" in the Blue Mountains [249].
Descriptions of oceanspray's root morphology were not found in the literature as of 2010.
Life span: This species rarely lives more than 30 years [10]. On the Jasper Ridge Biological Reserve, California, its mean life span was 4.5 years [1].
Physiology: Oceanspray is highly drought tolerant [51]. It has adapted to dry sites and drought by shutting down or slowing its rate of transpiration. In droughty conditions, it apparently uses water less efficiently than associated sclerophyllous species. Its large leaf area, however, may partially compensate for low water transpiration rates in summer. It is likely that oceanspray depletes water in upper soil layers rapidly in summer [40].
Antieau [13] suggested that oceanspray may differ in water-use efficiency and cold tolerance across its distribution.
Oceanspray is most frequent on south slopes of dry montane forests (see Site Characteristics); these sites typically burn earlier in the season or with higher severities than cooler, drier sites. In northern Idaho, Smith and Fischer [204] placed the Pacific ponderosa pine, Rocky Mountain Douglas-fir, and grand fir forests where oceanspray is most typically dominant in Fire Group 2. These forests tend to have warm temperature regimes, dry to moderate soil moisture, and are generally more productive—with heavier loads of downed woody fuels—compared to cooler or drier forests. Oceanspray also occurs in mesic to moist grand fir forests (Fire Group 7); these forests also have heavy fuel loads. See Smith and Fischer [204] for fuel load measurements representative of coniferous forest habitat types where oceanspray is important in northern Idaho.
In Pacific ponderosa pine-grand fir forests of Washington and Oregon, growing-season moisture content of shrubs, including oceanspray, averaged >125% over 2 years. Shrub moisture content peaked in June at ~175%. Moisture contents of dominant overstory trees are also described in this study [7].
In many forest types with oceanspray, fire exclusion has resulted in higher loads of woody debris compared to woody fuel loads when historic FIRE REGIMES were still functioning. In white fir stands in the Siskiyou Mountains of southwestern Oregon, large woody-debris loads were positively correlated with time-since-fire (P=0.01). Snag density was positively correlated with low (30 snags/ha) and high (23 snags/ha) fire severities (P=0.05). The authors attributed the correlation to nonconsumption of preexisting snags at low fire severity and creation of new snags at high severity. In this study, oceanspray dominated the shrub layer of white fir stands in dry, interior valleys [238].
Stand structure: Stand structure of communities where oceanspray is an important component of the vegetation is variable, as is the amount of fuel oceanspray contributes. On some sites, structure is open, with a sparse shrub component. In the west-central portion of the Cascade Range of Oregon, the coast Douglas-fir/oceanspray association displayed a relatively open stand structure (30-60% crown closure) of old growth, with few shrubs and a "very poorly developed" herb layer. Oceanspray cover averaged 5% [57]. Another study of coast Douglas-fir/oceanspray communities in the Cascade Range found that except for oceanspray, the tall-shrub layer was depauperate; low-shrub and herbaceous cover was also low. Incense-cedar, however, was encroaching in the subcanopy. Tree densities averaged 53 stems/ha for coast Douglas-fir and 5/ha for incense-cedar [153]. Live shrubs, including oceanspray as a dominant, comprised <5% of total stand biomass in mixed-conifer communities in the White Cap Wilderness Study Area of northern Idaho. Total shrub fuel loads ranged from 204 to 2,190 lbs/acre; shrubs were 0.6 inch to 27 inches (1.5-69 cm) tall, with 2% to 50% cover [26].
Some communities with oceanspray have denser overstories and/or understories. A coast Douglas-fir/oceanspray stand on the west-central portion of the Cascade Range, Oregon, had 70% tree cover, 46% shrub cover, and 36% herb cover. Aspect of the forest was southwest; it was the hottest and driest of 18 stand types examined [256]. Bailey [20] found coast Douglas-fir/oceanspray-salal habitat types off the southern coast of Oregon had relatively open canopies and "well-developed" shrub layers. Oceanspray averaged 30% cover [20]. Western redcedar-western hemlock forests often have a dense overstory, but understory cover of oceanspray and other shrubs may be sparse [204].
Mixed-conifer forests of southern Oregon and California are structurally and compositionally complex, with small conifers—often white fir and/or incense-cedar—often forming ladder fuels in a well-developed subcanopy. Snags and large, downed woody debris are common, but fuel loads are highly variable. Many of these mixed-conifer forests support a moderate to dense shrub understory, although some have few shrubs but a dominant herbaceous layer, and others have both depauperate understory and ground layers [34]. Stand structure in California's mixed-conifer forests was mostly open in the presettlement period [79].
Insect attacks increase snag densities in oceanspray habitats, which eventually increase dead and downed woody fuel loads. Youngblood and Wickman [250] provide data on stand structure, live and dead tree abundance, and shrub and herb cover of a grand fir-Douglas-fir forest attacked by Douglas-fir tussock moths 23 years prior. Oceanspray was an important component of the understory (5% cover); the site was in the Wenaha-Tucannon Wilderness in the Blue Mountains of Washington and Oregon [250].
Models: A few models were available for predicting oceanspray's contribution to total fuel loads as of 2010. Smith and Brand [205] review equations for predicting oceanspray biomass. Harris [90] presents models to predict oceanspray aboveground biomass and cover; the models were developed from data collected in coast Douglas-fir, grand fir, and western larch forests on the Umatilla National Forest. Brown [27] provides a model for predicting total aboveground oceanspray biomass and total leaf biomass based on basal stem diameter. Samples on which the model is based were collected in northern Idaho and western Montana [27].
Leaf area indices are used in some fuel models [49]. In the Siskiyou Mountains of southwestern Oregon, oceanspray had a large mean leaf area compared to associated shrubs; about twice as large as the leaf areas of associated greenleaf manzanita (Arctostaphylos patula) and redstem ceanothus (Ceanothus sanguineus) [40]. Agee and Lolley [6] placed oceanspray in fuel type 2: shrubs with thick stems but thin leaves.
Fresh oceanspray seed is dormant [74]. In the field, it likely requires overwintering to germinate. As of 2010, little research had been conducted on oceanspray's germination requirements [197]. Stratification at around 41 oF (5 oC) [197] for 15 to 18 weeks breaks dormancy in the laboratory [12,113,197].
Oceanspray seed may have low viability. According to a fact sheet, most seeds lack developed embryos, so only about 7% of a given seed lot may be sound [74].
Seedling establishment is uncommon [140,149,150,208,213] but has been documented a few times. Open stand structure [214], heat, and bare mineral soil may favor oceanspray germination and establishment (review by [196]). In the Oregon Coast Range, oceanspray seedlings emerged well (>70%) in both clearcuts and young, unthinned conifer stands; however, seedlings survived only in the young, unthinned stands [214]. Oceanspray established from seed 3 growing seasons after a debris flow on the Central Coast Ranges of southwestern Oregon [173]. See Seedling establishment in the Plant Response to Fire section for studies on postfire seedling establishment.
A review states that oceanspray seedlings grow slowly in their first 2 years of development [196]. Plants released by overstory removal may grow rapidly, however. Daubenmire and Daubenmire [51] found that in northern Idaho, oceanspray grew up to 15 feet (4.6 m) tall following harvest of the Rocky Mountain Douglas-fir overstory; this was twice its stature in unharvested Rocky Mountain Douglas-fir forests.
Soils: Oceanspray tolerates soils with a pH range from approximately 5.0 to 7.5, fine to coarse textures, and low nutrient and moisture content [74]. In western redcedar-western hemlock forests of northern Idaho, it had significantly greater cover in soils with pH above 6.1 than in soils with lower pH values (6% vs. ≤1% cover, P=0.05) [165]. Soils supporting oceanspray are often shallow ([87,94,100], review by [196]). In the Blue Mountains of Washington and Oregon, however, oceanspray is dominant in Pacific ponderosa pine-Rocky Mountain Douglas-fir forests on deep, fertile soils similar to those of Palouse prairie [84].
Oceanspray is common in sands and clay loams (review by [196]) but may occur in all soil textures. In the Cascade Range of Oregon, coast Douglas-fir/oceanspray communities occur on coarse soils and loams but not on fine soils [153]. A study in the Blue Mountains, however, found oceanspray presence was positively correlated with fine-textured soils (P<0.05) [249]. In western redcedar-western hemlock forests of northern Idaho, oceanspray cover, frequency, and importance value increased as soil organic matter increased; increases in importance values were significant (P=0.05) [165]. Soils supporting oceanspray are often stony [67,87,94,97,98,100], and oceanspray sometimes grows within rock crevices. It is common on talus slopes (review by [196]). In Nevada and western Utah, oceanspray grew on talus slopes near mountain meadows and in granite boulder piles [65].
Oceanspray occurs on a variety of parent materials. In the Cascade Range of Oregon, coast Douglas-fir/creambush oceanspray communities occur on poorly developed basalts, andesites, and other parent materials of volcanic origin [153]. At Oregon Caves National Monument, mixed-conifer forests with oceanspray occur on soils of diorite origin [240]. Poison-oak (Toxicodendron diversilobum)-creambush oceanspray-Mexican elderberry (Sambucus mexicana) communities of San Luis Obispo County, California, are associated with andesite-derived soils [235]. Photo © Br. Alfred Brousseau, St Mary's CollegeMoisture regime: Oceanspray is most common on dry sites. McDonald and others [148] list oceanspray as an indicator species of dry montane/shrub forests of the Northern Rocky Mountains. Oceanspray is also associated with dry montane forests in British Columbia [168,179] and elsewhere in the Pacific Northwest. It is an indicator species of very dry to moderately dry, nitrogen-medium soils in coastal British Columbia [110,111]; its occurrence decreases with increasing precipitation [111]. It also grows in dry to fresh soils in coniferous forests of interior British Columbia [168]. The western hemlock-coast Douglas-fir/oceanspray association occurs on some of the hottest and driest sites in the Cascade Range of Washington [222]. In the west-central portion of the Cascade Range in Oregon, Dyrness and Franklin [57] found the coast Douglas-fir/oceanspray association occurs on the dry end of coast Douglas-fir forest types. In an extreme case, oceanspray is "widespread but not abundant" on the Indian Plateau of southwestern Oregon. The plateau is a severe site known for widely fluctuating and extreme temperatures in winter and summer and a record of poor artificial regeneration of conifers [156].
Oceanspray is also reported from sites with moist to mesic soils. It is frequently associated with riparian communities (review by [196]). In southeastern Washington and northern Idaho, Pacific ponderosa pine/mallow ninebark-oceanspray communities dry out later in the growing season than Pacific ponderosa pine/common snowberry communities [152]. Oceanspray occurs on moist woodland edges in California [97] and in moist open woods in British Columbia [193]. In western redcedar-western hemlock forests of northern Idaho, oceanspray frequency was significantly greater on sites with 21% to 25% soil moisture content than on sites with drier or wetter soils [165].
Aspect and topography: This species is most common on warm, dry, south-facing slopes [67,98,165]. A grand fir/oceanspray association in southwestern Washington is common on exposed, south-facing slopes and on ridgetops. Sites having this association remain snow-free much of the year and experience extreme summer drought [221]. In Douglas-fir (Pseudotsuga menziesii) forests in the Columbia River Gorge of Washington, oceanspray had greatest cover on south-facing slopes (13%) and least cover in mesic ravines (6%) [243]. The coast Douglas-fir/oceanspray association in Oregon's Coast Ranges occurs most often on relatively steep, south- or west-facing slopes between 2,000 and 3,000 feet (600-900 m) elevation. The environment is hot and dry, and the growing season is long, with drought developing by midsummer. Snowpacks are not generally deep or persistent [94]. The western hemlock-Douglas-fir/oceanspray association is found in some of the hottest and driest forests in the western Cascade Range. Sites are "always" upper slopes and fairly steep, and drainage and solar input are "excessive" [87]. Coast Douglas-fir/oceanspray communities in the Cascade Range of Oregon are also most prevalent on dry, south-facing slopes [153]. In western redcedar-western hemlock forests of northern Idaho, oceanspray cover, frequency, and importance values were significantly greater on south- than north-facing slopes (P=0.05) [165].
Oceanspray grows on more mesic exposures as well. In montane zones on the Umatilla National Forest, it dominated the understory on north, northeast, northwest, and east aspects [90]; in western Oregon clearcuts it occurred only on north-facing slopes [246]. Oceanspray mostly grows on moist slopes in southern California [41], where it reaches the southern end of its distribution.
Elevation: Oceanspray occurs from sea level to about 7,000 feet (2,150 m) across its range. It mostly grows on low-elevation montane sites. In western redcedar-western hemlock forests of northern Idaho, oceanspray cover, frequency, and importance values were significantly greater on 3,000- to 3,400-foot (910-1,000 m) elevations than on higher-elevation sites (P=0.05) [165]. Oceanspray grows mostly on high peaks in the Great Basin (review by [196]).
Location Elevation eastern Washington and Oregon, Blue Mountains 1,700-4,800 feet [84] Deschutes National Forest, Oregon, east slopes >2,800 feet, from ponderosa pine to subalpine mixed-conifer zones [212] California <5,900 feet [97] southern California <4,500 feet [41] Nevada 4,500-9,500 feet [104] Pacific Northwest sea level to 5,500 feet [135]Climate: Oceanspray occurs mostly in dry zones [135], although it is characterized as a "predominantly humid zone species" in western Washington [53]. Annual precipitation across its United States distribution [37,56,97,137,215,241] ranges from 9.3 inches (236 mm) in central Oregon [56] to 57 inches (1,140 mm) in western Washington [137].
Browse: Oceanspray is a minor browse species [41,50,125,161,178,203,226]. Ungulates generally browse it only when more palatable forage is unavailable [84]. Many low-elevation, dry-site Douglas-fir forests with oceanspray are important cattle rangelands, but the cattle generally seek forage other than oceanspray [35]. Oceanspray is considered poor forage in Idaho [203] and an undesirable "competitor" with redstem ceanothus, a more desirable browse species [139]. Among ungulates in British Columbia, only Sitka black-tailed deer made much use of oceanspray [23].
However, because this species is common and readily available to wildlife and livestock on low-elevation rangelands, ungulates may make light but frequent use of oceanspray in summer [161,226]. Cattle use it as summer forage in northern Idaho [35,217] and northeastern Oregon [115].
Wildlife [125,161] and livestock [125] sometimes browse oceanspray more heavily [36,62,115], especially in late fall and winter when green forage is less available [125,197]. Snowshoe hares in the Flathead region of western Montana use the leaves and twigs for fall forage [3]. Studies on the Bitterroot National Forest and in the Rattlesnake Creek drainage of western Montana found elk, mule deer, and white-tailed deer preferred oceanspray as winter forage [109,146]. Columbian black-tailed deer in western Oregon browse oceanspray twigs in winter [47]; mule deer on the Los Padres National Forest of southern California also use oceanspray [184]. Oceanspray is heavily utilized by migrating mule deer and elk in central Washington [187].
Green clippings of oceanspray were found in dusky-footed woodrat shelters in Oregon [29], and the shrub is apparently palatable to native slugs in western Washington [31].
Palatability and/or nutritional value: Oceanspray is usually unpalatable to ungulates [157,158] and other browsing animals. A review rated its palatability as poor to fair for cattle and fair for domestic sheep [80]. A study on the Tillamook Burn of northwestern Oregon found mountain beavers browsed oceanspray less than expected based on availability [46]. New postfire sprouts are most palatable ([18,166], review by [196]). On burned sites in northern Idaho, big game species in northern Idaho preferred browsing sprouts of oceanspray and other shrubs to browsing current-year growth of shrubs on adjacent unburned sites, especially the first growing season after fire [18]. On one site, elk utilization of oceanspray increased from 1.3% before fire to 36.3% a year after prescribed fire; elk use dropped to 6.9% in postfire year 2 [127]. Asherin [18] also noted that big game species browsed oceanspray readily in postfire year 1, but use dropped after that. Browsing ungulates may pass over oceanspray sprouts if more palatable shrubs are available. On a wildfire-burned Rocky Mountain Douglas-fir/mallow ninebark habitat type on upper Selway River, northern Idaho, mule deer browsed oceanspray "minimally" in postfire years 2 and 3, while western serviceberry and Scouler willow were used heavily [105]. Following prescribed fires on the Lochsa Watershed in northern Idaho, elk preferred Scouler willow, western serviceberry, and Rocky Mountain maple sprouts to those of oceanspray [126].
Habitat: Conifer/oceanspray communities provide important habitat to a variety of wildlife species. Along the Umatilla River of Oregon, white-tailed deer used Pacific ponderosa pine-coast Douglas-fir/oceanspray and Pacific ponderosa pine/oceanspray communities more than expected based on availability (P<0.0001) [21]. On sky islands across Nevada and in western Utah, yellow-bellied marmot burrows were closely associated with oceanspray, "almost without exception" [64,65]. In the central Oregon Coast Ranges, oceanspray was found on streamside and upslope habitats where 18 of 22 small mammal species and 9 of 13 amphibian species known to the area were captured [145]. This shrub is also common in northern Idaho Pacific treefrog habitats [190].
Cover value: Oceanspray provides cover for a variety of species. Blue grouse hide beneath oceanspray and other shrubs [66]. Dense shrub understories in Rocky Mountain Douglas-fir/mallow ninebark habitat types—where oceanspray is common to codominant—provide visual and thermal cover for deer and elk; in addition, these sites supply nesting habitat, cover, and food for a variety of nongame birds and mammals [36].
Oceanspray may interfere
with conifer seedlings on plantations [168]. Because its roots are often shallow, oceanspray is likely to compete with conifer seedlings for water [40].
Grazing:
Oceanspray may decline with grazing despite its relative unpalatibility; its growth response in browsing and clipping studies has been mixed. In northern
Idaho sites with elk, moose, mule deer, and white-tailed deer, oceanspray was more common inside than outside exclosures [8]. Another northern Idaho study in
a Douglas-fir habitat type found oceanspray decreased in cattle-grazed stands [253]. Similarly, in the Bitterroot Mountains of northern Idaho, oceanspray showed greater density, cover, and frequency on ungrazed plots than on plots grazed by cattle (989 vs. 522 plants/ha; 2.6% vs. 0.6%; 4.4% vs. 1.3%,
respectively, for desnity, cover, and frequency) [252]. Garrison [71] recommends ≤50% to 60% utilization of oceanspray to prevent the species' decline.
Daubenmire and Daubenmire [51] reported that in eastern Washington and northern Idaho, overgrazing of Pacific ponderosa pine/mallow ninebark stands, in which oceanspray often codominates, may result in a disclimax ponderosa pine/bluegrass (Poa spp.) community.
Oceanspray is planted as an ornamental [197]. Leaf extracts show antifungal, antiviral, and cytotoxic properties ([102], review by [164]).
Traditional uses: Native Americans used oceanspray for making implements, as medicine [255], and sometimes as food. The long, straight, hard branchwood was highly prized for making arrow shafts [50,224], as well as digging sticks, fishing hooks, and needles [73,224]. Native Americans used oceanspray for treating viral and skin diseases ([73], review by [164]) and as a tonic [73]. The bark and leaves were dried and pulverized for application to burns or sores [86]. The Pima made tea from the leaves [118], and Native Americans in the Inland Northwest ate the seeds [55].
Oceanspray is among the first shrubs to initiate leaves in spring. Although floral buds swell in early [100] to late spring, oceanspray is a late bloomer [12]. Full flowering does not occur until late June or July and may continue into August in some areas [12,100]. Fruits mature in late summer and may persist until fall (reviews by [196,198]). Panicles and panicle branches typically persist through winter after drying in fall [196].
Leaf phenology is closely regulated by weather. In the Siskiyou Mountains of Oregon, leaf water conductance peaked in July [40]. On the Jasper Ridge Biological Preserve, mean leaf age was 4.5 months; leaves were drought-deciduous and mostly absent by August [1]. A study in the western redcedar-western hemlock zone of northern Idaho found summer or fall drought initiated leaf color change and leaf drop [55].
Oceanspray consistently shows a late and long period of flowering throughout its distribution:
Phenology of oceanspray across its range Area Event southern California flowers June-August [41] northern Idaho buds swell and burst late March-early April;Insects pollinate oceanspray (review by [196]). The flowers are perfect [100].
Antieau [13] suggested that mountain ranges restrict oceanspray breeding. A study across oceanspray's distribution in Washington and Oregon showed phenotypic differences in oceanspray (for example, in leaf area); these differences were related to geographic regions and climate [13].
Oceanspray is most common in early succession but occurs in all stages of succession. In mesic coniferous forests of northwestern Montana, it is approximately 5 times as dense in stands ≤150 years old than in old growth [14].
Seral occurrence: Disturbance favors oceanspray [111,113]. Kruckeberg [113] characterized oceanspray as a "colorful reclaimer of open or disturbed lands" of the Pacific Northwest, where it commonly establishes on recently logged sites, in second growth, and on roadbanks. It is especially common in seral Douglas-fir forests [111]. Following the Sundance Fire in northern Idaho, oceanspray was important or codominant in the first decade of postfire succession in Rocky Mountain Douglas-fir-western hemlock forests [206]. On another site in northern Idaho, oceanspray grew rapidly and dominated early-seral sites after a Rocky Mountain Douglas-fir forest was clearcut. The shrub layer regained precutting cover about 60 to 80 years after tree harvest [51]. Oceanspray seedlings established 3 growing seasons after a debris flow on the Central Coast Ranges of southwestern Oregon [173].
Oceanspray prefers open sites [111,218]. It is described as a "light demanding, early successional" species [218]. Logging and fire promote oceanspray by opening the canopy. A study at the Eastern Oregon Experiment Station showed shrub cover, including that of oceanspray, decreased with increasing cover of the mixed-conifer overstory. At about 90% canopy closure, shrub cover dropped to about 5%. However, even under a nearly closed canopy, a few shrubs remained alive in the understory, and seedlings of these shrubs established in canopy breaks [247]. In coast Douglas-fir/salal stands on foothills of the Cascade Range, Washington, maximum oceanspray cover occurred approximately 20 years after disturbance (clearcutting or wildfire); oceanspray generally declined after that [137]:
Oceanspray cover in different-aged Douglas-fir stands in Washington [137] Disturbance and stand age Postclearcut year 5 Postfire year 22 Postfire year 30 Postfire year 42 Postfire year 73 Cover (%) 1.72 4.46 3.34 2.13 2.84Defoliation and/or death of overstory trees due to insects may favor oceanspray. In the Blue Mountains, oceanspray showed 5% cover and 15% frequency 23 years after a record-breaking, 2-year attack by Douglas-fir tussock moths. About 1,250 miles² (3,240 km²) of a grand fir-Douglas-fir forest was affected by the outbreak [250].
Where it is a minor species, oceanspray may not decline with canopy closure. In western redcedar-western hemlock forests of northern Idaho, its cover, frequency, and importance values were not significantly different in 5 canopy-cover classes ranging from 1% to 100% closure. Oceanspray had ≤1% cover in all canopy-cover classes. Similarly, its cover, frequency, and importance values in these forests were not significantly different between logged, logged-and-burned, single-broadcast-burned, or multiple-broadcast-burned sites and sites with no history of logging or prescribed fire [165].
Logging: Lightly-shaded areas, such as those occurring a few decades after thinning, can promote oceanspray growth [194]. In Douglas fir-western hemlock forests of coastal Oregon, oceanspray was associated with intermediate tree densities (P<=0.01) [199]. In Douglas- fir stands in northern Idaho, its cover peaked about 20 years after logging [176].
Oceanspray cover in unlogged and logged Douglas-fir stands in northern Idaho [176] Treatment Unlogged Logged 13 years previous Logged 20 years previous Logged 40+ years previous Cover (%) 0.6 21.4 26.8 8.0On the Fort Lewis Military Reservation of Washington, a late 1990s study found oceanspray cover was greater in a coast Douglas-fir/oceanspray forest that had been clearcut in the 1920s and thinned twice afterwards (2.5% oceanspray cover) than in a coast Douglas-fir/oceanspray forest that had been partially cut only once, in the 1930s (1.5% oceanspray cover) [220]. In Pacific ponderosa pine and Rocky Mountain Douglas-fir habitat types of the Swan Valley, Montana, oceanspray cover was greater on clearcut (15%) and plantation (10%) plots than on untreated plots (8%) [69].
In the Klamath Mountains of Oregon and California, shrubfields of oceanspray and other sprouting shrubs develop after logging or fire when conifers fail to regenerate in the early postfire community; conifers eventually replace the shrubs on most sites [149].
Logging does not favor oceanspray on all sites. In northern Idaho logging reduced oceanspray frequency slightly compared to its frequency in the understory of an adjacent unlogged site. The study site was in a western hemlock/pachistima forest. A tall-shrub (>3 feet (1 m)) community developed after logging; oceanspray was a component of this early-seral, tall-shrub community. On cut sites, oceanspray had 1.4% frequency 7 years after logging and 0.7% frequency 25 years after logging. It had 2.1% cover on the unlogged site 25 years after treatments [242].
See Plant response to fire for more information on oceanspray occurrence in seral postfire communities.
Late-successional occurrence: Oceanspray sometimes occurs in late succession. In Glacier Park's western redcedar-western hemlock forests, it is mostly restricted to late-seral or climax communities [81]. Oceanspray also occurs in late succession in western redcedar-western hemlock and grand fir forests of Montana [186], and it is a late-successional or climax species in some western hemlock habitat types of Washington [95] and northern Idaho [251]. However, Henderson and others [95] point out that on the Olympic National Forest, climax western hemlock/salal-oceanspray forests rarely develop due to recurrent fires. Coast Douglas-fir dominates the seral stands; oceanspray often codominates the understory of these seral stands [95]. Oceanspray also dominates the understories of late-successional Douglas-fir forests in Oregon [256] and Montana [186]. In mixed-conifer forests of western Oregon and California, oceanspray and other deciduous shrubs are more likely to dominate in late succession on north-facing and other mesic slopes than on south-facing, dry slopes [240].The scientific name of oceanspray is Holodiscus discolor (Pursh) Maxim (Rosaceae) [97,99,103,117,193].
The Holodiscus taxonomy is confused because oceanspray, rockspirea (H. dumosus),
and small-leaved rockspirea (H. microphyllus) are taxonomically and morphologically very similar [45,163]. Authorities separating these 3 closely related taxa do so based on different leaf morphologies [45,136] and distributions [136]. This review follows the taxonomy of Lis (in [97]), who authored the Flora of North America's [63] Holodiscus chapter. In Lis's treatment, oceanspray, rockspirea, and small-leaved rockspirea are treated as separate and distinct species [97]. Some systematists lump either oceanspray and rockspirea [104,236], oceanspray and small-leaved rockspirea [103], or all 3 taxa [233] into single species.
Oceanspray could potentially be used on Burned Area Recovery sites, although to date (2010), there was no documentation of its suvivorship after transplanting onto burns. It is used successfully for erosion control ([154], review by [196]), highway plantings, windbreaks, riparian plantings, and wildlife plantings (reviews by [196,197]). It establishes readily through natural regeneration on burned sites [35,246] (see Successional Status and Plant response to fire). In northern Idaho, for example, oceanspray dominated (48% of total understory cover) a Pacific ponderosa pine-Rocky Mountain Douglas-fir stand in early postfire succession; its size (10-15 feet (3-4.6 m)) and relative unpalatability allowed it to compete successfully with other shrubs for light, moisture, and space. Because it is a "poor forage species", researchers predicted it would dominate the burn until crowded out by conifers [203].
Oceanspray is propagated from cuttings or seed [12,113], with cuttings the usual method. A 2004 review found oceanspray seeds were "rare and costly" [196], and as of 2008, there were no published guidelines for growing this species from seed [197]. See these sources: ([74], reviews by [196,197]) for information on propagating oceanspray. Plants are available commercially [74].
Holodiscus discolor, commonly known as ocean spray or oceanspray, creambush, or ironwood, is a shrub of western North America.[3][4][5]
Holodiscus discolor is a fast-growing deciduous shrub usually from to 1.2–1.5 metres (4–5 feet) in width, and up to 2.1 m (7 ft) tall. Its alternate leaves are small, 5–9 centimetres (2–3+1⁄2 inches) long and 4–7 cm (1+1⁄2–3 in) broad, lobed, juicy green when new.[6] The young branches have longitudinal ridges.
Cascading clusters of white flowers drooping from the branches give the plant its two common names. The flowers have a faint sweet, sugary scent. The bloom period is May to July.
It bears a small, hairy fruit containing one seed which is light enough to be dispersed by wind.
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Illustration
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Specimen in Tahoe National Forest, California
Leaves
Close-up of flowers
The plant is common in the Pacific Northwest, and throughout California in diverse habitats including California mixed evergreen forest, California oak woodlands, chaparral, Coast redwood forest, Douglas-fir forest, Yellow pine forest, Red fir forest, and Lodgepole pine forest. It is native to regions of California including the High Sierra Nevada, Northern and Southern California Coast Ranges, Klamath Mountains, Santa Cruz Mountains, Western Transverse Ranges, and the San Gabriel Mountains.
It is found in both openings and the common understory shrub in a variety of forest overstories from 300–1,300 m (980–4,270 ft) in elevation. In open mountain habitat in the Sierra Nevadas it can be found as high as 3,500 m (11,500 ft). It is found in a variety of habitats, from moist coastal forests to drier, cooler mountains of inland California. The plant is found in areas prone to wildfire, and it is often the first green shoot to spring up in an area recovering from a burn. It is commonly found in chaparral communities, a fire ecology ecosystem which evolved with burning periodically. It also may grow in areas cleared by logging.
In the California black oak woodland plant community, common understory associate species include Toxicodendron diversilobum (Western poison-oak), Heteromeles arbutifolia (toyon), and Dryopteris arguta (coastal wood fern).[7]
It is of special value as a pollinator plant for native bees and butterflies.[8] It is also a larval host to Lorquin's admiral, pale tiger swallowtail, and spring azure caterpillars.[9]
Historically, the plant has been used by Indigenous peoples for many purposes.[10] Raw and cooked seeds were eaten,[11] and leaves were mixed with those of other plants and boiled with small game animals.[12] Many tribes used the wood and bark for making tools and furniture. Noted for the strength of its wood, it was often used for making digging sticks, spears, arrows, bows, harpoons and nails. The wood, like with many other plants, was often hardened with fire and was then polished using horsetail.[13]
Comox natives use oceanspray when flowering as an indicator of the best time to dig for butter clams.[14]
The Lummi used the flowers as an antidiarrheal and the leaves as a poultice. Several Native American tribes, such as the Stl'atl'imx, would steep the berries in boiling water to use as a treatment for diarrhea, smallpox, chickenpox and as a blood tonic.[5]
Holodiscus discolor, commonly known as ocean spray or oceanspray, creambush, or ironwood, is a shrub of western North America.
