BOTANICAL AND ECOLOGICAL CHARACTERISTICS

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

Aboveground description: Field sagewort is a native forb (with 1 nonnative subspecies) with highly variable forms and habits. Plants are biennials or short-lived perennials and produce 1 to many stems that may reach 4.9 feet (1.5 m) [11,33,43]. Stems arise from a woody caudex [27,59]. Growth forms vary from mounded to spreading [49,59]. Basal leaves are crowded and measure 0.8 to 4 inches (2-10 cm) long by often less than 2 mm wide. Basal leaves may or may not persist. Leaf hairiness ranges from glabrous to densely villous. Stem leaves are smaller and have less pronounced dissection than basal leaves [43,67]. Flowers are inconspicuous and occur in spike- or panicle-like inflorescences. Field sagewort produces 5 to 20 ray and 6 to 40 disk flowers, but only ray flowers are fertile [11,49]. Fruits are achenes measuring around 0.8 mm long and lacking a pappus [11]. Shipley and Parent [99] report that seeds weigh about 0.003 g, based on an average of at least 25 seeds.

Infrataxa: Because there is little available information on field sagewort, and available information often refers to a single subspecies and/or variety, this review will identify subspecies and varieties consistent with the literature cited. Descriptions of field sagewort infrataxa are summarized below:

Artemisia campestris subsp. caudata is most often described as a single-stemmed biennial [34,56]. However, of A. c. subsp. caudata plants observed throughout Alberta, approximately 20% were perennial and at least 50% had 2 or more stems [80]. Artemisia campestris subsp. caudata may be more aptly described as a monocarpic perennial [102,132], but in populations studied along the eastern shore of Lake Huron, some plants survived after their reproductive period, and a small percentage of plants (4.5%) flowered in more than 1 growing season [102]. Stems range from 1 to 4.9 feet (0.3-1.5 m) tall, are often unbranched, and arise from a large taproot [46,89,105]. Numerous basal leaves are present in the first growing season. Both basal and stem leaves are deeply and finely dissected. Leaves may be pubescent when young but become glabrous with age [30,49,56]. Artemisia campestris subsp. caudata produces 20 to 40 flowers/head, and heads are arranged in elongate narrow panicles. Outer pistillate flowers are fertile, and inner flowers are perfect but have abortive ovaries [30,46,75]. Glabrous achenes measure 0.8 to 1 mm long [89]. Seeds are small. One thousand seeds weigh approximately 0.1 g [103,105].

Artemisia campestris subsp. campestris is a nonnative perennial. It is the only nonnative subspecies described in this review. Artemisia campestris subsp. campestris commonly produces several stems of 1 to 2 feet (0.3-0.5 m) tall. Plants are very leafy at the base and much less so above. Leaves are pubescent when young but glabrous when mature [49].

Artemisia campestris subsp. borealis var. borealis is a perennial that grows as a 0.3- to 1-foot (0.1-0.3 m)-tall mound [2,34]. Stems are simple or branched [59]. Leaves, concentrated at the plant base, are dissected into long narrow lobes [2,59,93]. Few flower heads occur in the raceme- or spike-like inflorescences [2,34].

Artemisia campestris subsp. borealis var. scouleriana is a perennial growing 1 to 3 feet (0.3-1 m) tall [56,86]. Several clustered stems grow from a compact, branching caudex [27]. Basal and stem leaves are silky with hairs. Basal leaves are persistent [27,49,75,86,123]. Head flowers consist of 5 to 20 fertile pistillate flowers and 12 to 30 functionally staminate disk flowers. Inflorescences are large, relaxed or open, and contain many heads [27,56,123].

Artemisia campestris subsp. borealis var. petiolata and A. c. subsp. b. var. wormskioldii have the most restricted distributions and are not well described. For more information on these species, see [56,122].

Belowground growth: Field sagewort produces a large taproot [11,89,105]. The often biennial root of A. c. subsp. caudata is also considered large, especially on sand dunes [49]. Mature A. c. subsp. caudata in Benzie County, Michigan, produced lateral roots that extended 20 to 30 feet (6-9 m). However, extension direction was not described. Young plants that were about 4 inches (10 cm) tall had short taproots, and "very prominent" taproots were only occasionally observed. Root length decreased with increased presence of organic matter or humus layers, and lateral roots were shorter and finer in organic soils than sandy soils [117].

Roots of mature A. c. subsp. borealis var. borealis excavated from relatively undisturbed sites in the Great Plains were primarily confined to the top 3 inches (8 cm) of soil. Maximum root spread, lateral root abundance, and lateral root branching were within the top 3 inches (8 cm) of soil. Just 4 to 6 moderately branched roots extended to depths of 2 to 3 feet (0.6-1 m) [118]. Artemisia campestris subsp. borealis var. borealis plants excavated from sandhills near Yuma, Colorado, had taproots reaching 8 feet (2 m) and lateral roots extending 1 to 2.5 feet (0.3-0.8 m) from the taproot. Excavated plants were 1 to 1.5 feet (0.3-0.5 m) tall and had between 5 and 10 large branches. "Strong, woody taproots" had diameters of 6 to 11 mm near the soil surface, but diameter quickly tapered to less than 1.5 mm at depths of 1 foot (0.3 m) or more. Numerous laterals ranging from "threadlike" to over 2 mm in diameter occurred just below the soil surface to a depth of 1.5 feet (0.5 m). All lateral roots were multibranched with very fine sublaterals 1 to 3 inches (3-8 cm) long [119].

Pollination: Field sagewort flowers are wind-pollinated [3,102].

Breeding system: Field sagewort produces fertile pistillate flowers and functionally staminate flowers with abortive ovaries [27]. Cross pollination is predominant [102].

Seed production: Flower and seed production by field sagewort is variable, and likely influenced by plant size and site conditions [102]. Research suggests that abundant flower production may not necessarily result in abundant seed production [57]. In Colorado's Rocky Mountain National Park, many A. c. subsp. b. var. borealis produced abundant flowers but failed to produce mature fruits or seeds [57]. In south-central Montana, field sagewort seed rain was measured in late-seral alpine vegetation characterized as Ross avens (Geum rossii) turf. Field sagewort seed rain averaged 0 in 1988, 8±6 (SE) seeds/m² in 1989, and 85±54 seeds/m² in 1990 where field sagewort cover was 0.01% in mid-August of 1988 [24]. In North Dakota, a single "average, well developed (A. c. subsp. caudata) plant, growing with comparatively little competition" produced 215,000 mature seeds. The researcher noted many immature seeds. Seed counts were conducted when the number of mature seeds was likely at a maximum [103].

In A. c. subsp. caudata populations in Pinery Provincial Park of Lambton County, Ontario, plants that flowered had a rosette diameter of at least 5.1 inches (13 cm) in the preceding growing season, and the majority of flowering plants were 3 years old. Seed production by A. c. subsp. caudata, while variable from year to year, showed patterns among sites. Seed production was consistently lowest in the "transition zone" where dunes were 800 to 2,100 years old and supported dense ground cover of forbs and grasses. Seed production was consistently highest in the "slack area" where dunes were 100 to 400 years old, vegetation was sparse, and conditions were "harshest". Average seed production ranged from 250 seeds/plant in the transition zone to 2,000 seeds/plant in the slack area. All immature, mature, and deformed seeds were counted to estimate seed production, and plants in the transition zone had the greatest percentage of immature and deformed seeds and produced the lightest seeds. Around 50% of total seeds produced came from about 15% of the population [102].

Seed dispersal: Field sagewort seed is primarily wind-dispersed. Without a pappus, seed typically remains near the parent plant or is dispersed short distances by wind. Stairs [102] observed zero dispersal distance when seed germinated on a parent plant that had fallen over and become partially buried in sand [102].

Seed of A. c. subsp. borealis was recovered from wind-blown debris collected from St Mary's Glacier on the eastern slope of Colorado's Front Range. Debris collections were made for 2 years at an elevation of about 11,000 feet (3,350 m). Five A. c. subsp. borealis seeds germinated from collections made in one of the years. Distance between debris and A. c. subsp. borealis populations was not reported [17].

Seed banking: Information on the density and longevity of field sagewort seed in the soil seed bank under true field conditions is lacking. Studies indicate that field sagewort seed has a clumped distribution in sand dune habitats [10,102]. Artemisia campestris subsp. caudata seedling emergence was 335 seedlings/m² from 1 of 4 soil samples in coastal sand dune sites on the Cape Cod National Seashore, Massachusetts. On the site with abundant A. c. subsp. caudata emergence, the density of adult plants was 1.9 plants/m². Soil samples were collected in mid-March. There were no adult plants present on the other soil collection sites where A. c. subsp. caudata emergence was 0 to 1 seedling/m². Researchers suggested that the trapping of seed by other vegetation or in depressions, and/or the burial of seed still attached to the inflorescence may have created the clumped distribution [10].

Greenhouse and field experiments using field sagewort seed from southern Ontario indicate that seed may remain viable in the soil for at least 16 months. Researchers collected seed from native populations from June 1996 to June 1997. Seed was stored in a freezer for up to 1 year. In late spring, known quantities of seed were buried in pots in old fields. Pots were treated with fungicide, made inaccessible to invertebrates, or left unprotected. After 4 months, 11 months, and 16 months of burial, pots were removed, and seedling emergence was monitored in a greenhouse. After 4 months, germination was about 20%, regardless of treatment. After 11 and 16 months, germination was again around 20% for control pots, but was about 40% in pots treated to keep out fungi and invertebrates [15].

Germination: Beyond a requirement of adequate moisture, information on the natural conditions facilitating field sagewort germination is lacking. Waterman [117] reports that A. c. subsp. caudata "germinates freely" on open dunes and along forest edges. In the available literature (2007), 40% germination was the maximum reported for field sagewort [14]. Studies of A. c. subsp. caudata populations in Pinery Provincial Park revealed emergence flushes with periods of heavy spring and fall rainfall. Seedlings emerged in clumps, again indicating poor seed dispersal by this species [102].

Field sagewort seed collected in southeastern Canada germinated rapidly, and the maximum germination rate was 33%. Researchers monitored the germination of 100 field sagewort seeds for 30 days. Seeds, collected in September or October, were kept at 40 °F (4 °C) for 9 months before being encouraged to germinate in greenhouse conditions. It was 3 days before the first seed germinated, and a maximum of 23 seeds germinated in a single day [99].

Cold temperatures were apparently not required for A. c. subsp. caudata seed germination in western North Dakota. Seed collected through October was evaluated after dry-room temperature, dry-cold, and moist-cold storage. Germination tests occurred monthly after at least 1 month of storage. Seeds stored at room temperature under dry conditions had a maximum average monthly germination rate of 40% following 3 months of storage and a minimum rate of 8% after 6 months. Under dry-cold conditions, where temperatures mimicked western North Dakota's normal outdoor temperature fluctuations, germination reached 25% after 2 months of storage with a minimum of 12% after 6 months. In moist-cold conditions, the highest germination rate was 36% after 4 months of storage, and lowest was 11% after 5 months [14].

Seedling establishment/growth: Optimal conditions for field sagewort seedling establishment and growth likely include adequate or above-average precipitation. Information on safe sites and substrate preferences is lacking.

Growth: In the first year after cattle were removed from the mixed-grass Arapaho Prairie in Arthur County, Nebraska, field sagewort was abundant, and vegetative growth and flowering were described as "massive"; but in the next year field sagewort was rare. Growing season precipitation levels were much above average when field sagewort was abundant and were at their lowest in 4 years when field sagewort was rare [87].

In Pinery Provincial Park, Ontario, a researcher found that increased A. c. subsp. caudata rosette size (based on diameter measurements) was correlated with a decreased probability of over-wintering mortality and mortality in the next year. Desiccation was considered the primary cause of plant mortality. Survival probability also decreased with increased A. c. subsp. caudata age [102].

Vegetative regeneration: As of this writing (2007), sprouting from the caudex after top-kill has not been described. Populations of A. c. subsp. caudata observed in Pinery Provincial Park, however, did produce new stems following tissue damage. There were a greater number of single-stemmed plants on sites where plants received the least amount of aboveground damage [102].

Aspect: In the badlands of North Dakota, A. c. subsp. caudata occurred on south- but not north-facing slopes. Southern aspects were drier and had shallower soils with less organic matter than north slopes. Herbaceous vegetation dominated southern aspects. Northern aspects were dominated by trees and shrubs. The study did not determine which, if any, factors most affected A. c. subsp. caudata presence [23].

Climate: Field sagewort's wide distribution implies wide climatic tolerances. Temperatures average 10 °F (-4 °C) in field sagewort habitat in alpine vegetation in Quebec's Gaspe Provincial Park, and annual precipitation averages 65.4 inches (1,660 mm). Snow accounts for 33% of the annual precipitation [100]. In Lesser Slave Lake Provincial Park, Alberta, field sagewort habitats experience a humid continental climate with short, cool summers and long, cold winters. Frost-free days average average 80/year [70]. A continental climate with wide annual and diurnal temperature fluctuations is described for field sagewort habitats in North Dakota. Temperatures average 12 °F (-11 °C) in January and 70 °F (21 °C) in July. Annual precipitation averages 15 inches (380 mm), and 110 to 119 frost-free days are typical in field sagewort habitats in North Dakota [23]. A semiarid to desert-like climate prevails in western Texas field sagewort habitats. In Bailey County, January and July temperatures average 36 °F (2.4 °C) and 77.2 °F (25.1 °C), respectively, and in Winkler County temperatures average 44 °F (6.9 °C) in January and 84 °F (28.9 °C) in July. Precipitation averages 11 inches (282 mm)/year in Winkler County and 17 inches (442 mm)/year in Bailey County [106].

Elevation:

Researchers report that A. c. subsp. borealis var. borealis occurs in subalpine and alpine sites in Montana, Colorado, and Wyoming [34,56]. Artemisia campestris subsp. borealis var. scouleriana commonly occupies lower elevation sites than A. c. subsp. borealis var. borealis [56].

Soils: Sandy soils are most often described for field sagewort habitats. Salty and serpentine soils are also tolerated. In southern Saskatchewan, A. c. subsp. caudata occurs in semi-halophytic vegetation types with saline and calcareous soils. Vegetation is likely affected by salts only during times of high soil moisture [32]. Artemisia campestris subsp. borealis var. borealis occurs in arctic coastal tundra on Alaska's North Slope that is inundated with salt water when winds are strong. Soils in this area are sandy loams and have a pH of 7.3 [21]. On Mount Albert in Quebec's Gaspe Provincial Park, A. c. subsp. borealis is most frequent in alpine vegetation occupying serpentine-rich soils [100].

Old fields: Artemisia campestris subsp. caudata occurred in old fields abandoned for 1 to 22 years in Colorado's Black Forest. Frequency was 10% on 1-year-old fields dominated by annual weeds. On 4-year-old fields with perennial grasses and weeds, the frequency of A. c. subsp. caudata was 80%. Its frequency was 100% in perennial weed-ponderosa pine (Pinus ponderosa) vegetation dominating 9-year-old fields and 90% in 22-year-old fields characterized as ponderosa pine-grasslands [72].

Stream banks: Along eastern Colorado's Plum Creek, A. c. subsp. caudata occurred on stable bars but not on "recently reworked channel sediments". Stable bars, adjacent to the channel bed, were inundated for a few days in the spring. Whether or not inundation period alone restricts A. c. subsp. caudata from the earliest formed sand substrates could not be determined from this study [41].

Sand dunes/lake shores: Field sagewort is an early colonizer [35,82,130] and often persists in mid- and late-seral sand dunes and lake shore communities. In southern Saskatchewan, field sagewort occurs on both active and stabilized dunes. Active dunes experience current erosion and/or deposition, and stabilized dunes lack evidence of recent erosion [58]. In the Point Beach State Forest in Two Rivers, Wisconsin, field sagewort is "fairly common" from interdune troughs to forest margins [111]. In Great Lake sand dune systems, A. c. subsp. caudata occurs in communities characterized as being in early, mid, late, and advanced stages of succession [18]. Artemisia campestris subsp. caudata occurs as a pioneer in sand succession of the Platte Plains region of Benzie County, Michigan, and occupies sites at mixed pine-oak forest edges nearest the lake [116]. On the east shore of Lake Ontario, A. c. subsp. caudata occurs in communities receiving high and low levels of recreation use [16].

In 1993, increasing water levels facilitated sand accumulation on newly exposed dunes on Lake Huron shores in Cheboygan County, Michigan. Sand accumulation varied from 1.6 to 13 inches (4-32 cm). Field sagewort stem density increased 166% from 1992 to 1996 [8]. When a 2,375-year-old dune chronosequence was sampled in Wilderness State Park on northern Lake Michigan, field sagewort occurred only on young dunes (25-175 years old). Young dune environments were characterized by strong winds, sand burial and erosion, high insolation, high evaporation, and low nitrogen and phosphorus availability. Conditions were less harsh with increased distance from the lake. Establishment of forest species began on 145-year-old dunes [71].

Forests: In boreal forests of western Canada, A. c. subsp. borealis var. borealis occurs, although not abundantly, as a pioneer on open sites with sandy soils [1].

Prairies: Climax and disturbed prairies provide field sagewort habitat. Artemisia campestris subsp. borealis var. scouleriana occurs in mixed-prairie climax communities [49]. In south-central South Dakota, A. c. subsp. caudata is considered a "chief" forb in climax grasslands dominated by needle-and-thread grass (Hesperostipa comata), threadleaf sedge (Carex filifolia), and blue grama (Bouteloua gracilis) [109]. Field sagewort occurred in relatively high-quality prairie remnants dominated primarily by native species and in prairies with a history of disturbance which may have included tilling, herbicide treatment, and/or season-long grazing [55]. In Alberta's Wood Buffalo National Park, field sagewort was more common and had a greater abundance on disturbed than undisturbed shortbristle needle-and-thread (H. curtiseta)-dominated dry grasslands. Compaction and erosion were characteristic of disturbed sites [91].

Alpine communities: While field sagewort is considered a colonizer of disturbed alpine sites [20], severity of disturbance can affect its presence. On the Beartooth Plateau in south-central Montana, field sagewort occurred in a late-seral alpine community disturbed only by pocket gophers but was absent from an early-seral gravel pit. Top and subsoil were removed from the gravel pit 35 years earlier [24].

FIRE ECOLOGY

• FIRE ECOLOGY OR ADAPTATIONS
• POSTFIRE REGENERATION STRATEGY

Fire regimes: Field sagewort occupies a variety of habitats in a wide range of environments making it impossible to describe a single fire regime for this species. Field sagewort likely experiences and tolerates a wide range of fire regimes. Field sagewort's intolerance of shade and tolerance of disturbance suggests that it may be favored by recurrent fire. In Wisconsin, dry prairies and oak barrens providing field sagewort habitat are maintained by recurrent fire [28,29].

Researchers found increases in sagebrush (assumed to be field sagewort in dry areas) pollen after each fire recorded in a 580-year fossil pollen and charcoal record from Fariya Lake in northern Alberta. Sixteen fires were detected in 580 years, and the estimated fire-return interval was 34 years. This estimate closely matched the fire cycle estimated from dendrochronology studies done in jack pine (Pinus banksiana) forests in the adjacent Wood Buffalo National Park. Current vegetation surrounding the lake includes jack pine on the benches and slopes, paper birch (Betula papyrifera) between ridges, and black spruce (Picea mariana) in moist depressions. For more on this study, see Discussion and Qualification of Plant Response to Fire [68].

The following table provides fire-return intervals for plant communities and ecosystems where field sagewort may be 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".

FIRE EFFECTS

• IMMEDIATE FIRE EFFECT ON PLANT
• DISCUSSION AND QUALIFICATION OF FIRE EFFECT
• PLANT RESPONSE TO FIRE
• DISCUSSION AND QUALIFICATION OF PLANT RESPONSE
• FIRE MANAGEMENT CONSIDERATIONS

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
Although field sagewort occurs in many habitats, very few studies describe field sagewort's response to fire, and of the few fire studies mentioning field sagewort, all lack specifics. All that can be concluded from these studies is that field sagewort appears in early postfire communities and persists on repeatedly burned sites.

Researchers noted that A. c. subsp. b. var. scouleriana was important in the first year following an early fall fire in shrub live oak (Quercus turbinella)-dominated chaparral in central Arizona's Sierra Ancha Experimental Forest. Herbaceous vegetation was reportedly "almost nonexistent" before and increased "greatly" after the fire. Forbs were present for the first 5 postfire sampling years. Abundance values were not reported [83].

Field sagewort abundance increased in the first postfire year on little bluestem (Schizachyrium scoparium)-dominated plots in south-central Minnesota's Cedar Creek Natural History Area that was spring burned at 4-year intervals (5 fires in 17 years). Field sagewort abundance was not reported on similar plots that were spring burned annually or every other year, but the researcher reported that fire frequency differences produced only minor changes in species composition and did not affect aboveground productivity [64].

Fossil pollen and charcoal records from Fariya Lake within jack pine forests of northern Alberta indicate that field sagewort is likely abundant following fire. Researchers found significant (P<0.05) positive correlations of Artemisia spp. (likely field sagewort on dry sites) within 5 years after peaks in the macroscopic charcoal accumulation rate. For information on the fire regime in this area, see Fire regimes [68].

MANAGEMENT CONSIDERATIONS

• IMPORTANCE TO LIVESTOCK AND WILDLIFE
• VALUE FOR REHABILITATION OF DISTURBED SITES
• OTHER USES
• OTHER MANAGEMENT CONSIDERATIONS

In the winter in the Bridger Mountains of Montana's Gallatin County, Rocky Mountain mule deer fed on A. c. subsp. borealis var. borealis. Observations of feeding on A. c. subsp. borealis var. borealis constituted 4% of the total 505, year-long feeding observations [127].

Artemisia campestris ssp. borealis var. borealis was common in arctic coastal tundra sites used by caribou and migratory Canada geese on Alaska's North Slope. Consumption of seeds or herbaceous growth was not noted [21]. Artemisia caudata subsp. caudata was abundant in eastern cottontail winter habitats in Allegan County, Michigan, but was not frequently consumed [51].

In the Gateway National Recreation Area in the New York and New Jersey harbors, researchers monitored a protected diamond-backed terrapin nest. Seven of nine eggs were penetrated by roots. The nearest plants were A. c. subsp. caudata and bayberry (Myrica pennsylvanica), but roots that penetrated the eggs were not identified [38].

Palatability/nutritional value: Field sagewort is considered highly unpalatable to livestock, and its use can indicate overgrazing [49].

Cover value: No information is available on this topic.

OTHER MANAGEMENT CONSIDERATIONS:
Allelopathy: Artemisia campestris subsp. caudata litter may indirectly inhibit the growth of other species. In a greenhouse, plants native to the sand dunes of Lake Huron, Ontario, were sown in soil with A. c. subsp. caudata leaf litter. Seeds and seedlings in litter soil had reduced germination or growth when compared to seeds and seedlings in soils without A. c. subsp. caudata leaf litter. Allelopathic compounds were identified as metabolites formed during leaf litter decomposition by microorganisms. Researchers noted several reasons that the allelopathic impact A. c. subsp. caudata on neighboring species is likely to be low in sand dune habitats. The unstable and well-draining nature of sand facilitates a continuous decrease in released metabolites through rapid leaching and dissipation; and sand dunes lack organic matter, support a weak microfauna, and have slow litter decomposition. Also, A. c. subsp. caudata is a monocarpic perennial that loses inhibitory compounds soon after death [132].

Health: Field sagewort is a common allergen [49,105].

Host: Artemisia campestris subsp. caudata is the only known host to clustered broomrape (Orobanche fasciculata), an herbaceous, obligate, root parasite [92]. Clustered broomrape is threatened or endangered in several Great Lakes states [110]. In Sheboygan County, Wisconsin, larger A. c. subsp. caudata plants supported larger, clustered broomrape plants [92].

Nonnative species: Field sagewort growth and/or recruitment may be restricted by leafy spurge (Euphorbia esula). In "heavily infested" mixed-grass prairie in south-central Manitoba, field sagewort occurred only where biocontrol agents, flea beetles (Aphthona nigriscutis), had been released 6 years earlier. Field sagewort did not occur in 2- or 4-year-old release sites or in nearby nonrelease areas. Average leafy spurge cover around 6-year-old release sites was 98% lower than nearby nonrelease sites. At 2- year-old and 4-year-old release sites, leafy spurge cover was 20% and ~38% lower than nonrelease sites [77].

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