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Species
Hieracium aurantiacum L.
IUCN
NCBI
EOL Text
Foodplant / parasite
uredium of Puccinia hieracii var. piloselloidarum parasitises live leaf of Pilosella aurantiaca
More info for the terms: fire suppression, prescribed fire, presence, restoration, wildfire
Potential for postfire establishment and spread: Orange hawkweed possesses several traits that make it adapted to surviving and establishing after fire (see Fire adaptations). The available literature suggests that orange hawkweed may establish after fire; it was documented in areas following both wildfire [43,80,107] and prescribed fire [1,29,30,70,90], and in some of these cases, it was not detected prior to fire [29,30,90] (see Plant response to fire).
Preventing postfire establishment and spread: Because of its potential for long-distance seed dispersal and the suggestion that orange hawkweed established on burned sites via wind-dispersed seed [29], monitoring areas in close proximity to known populations of orange hawkweed for potential establishment is advised. Orange hawkweed establishment may occur soon after fire (e.g., 1 year after wildfire in British Columbia [80], 2 years after prescribed fire in Ontario [90] and New Brunswick [29], 2 and 4 growing seasons after prescribed fire in Michigan [70], and 4 years after wildfire in Australia [105]), or may be delayed (e.g., 10 years after wildfire in British Columbia [30]). These observations, combined with orange hawkweed's persistence in the seed bank, suggest that long-term monitoring may be necessary to limit orange hawkweed's establishment in burned areas.
Preventing invasive plants from establishing in weed-free burned areas is the most effective and least costly management method. This may be accomplished through early detection and eradication, careful monitoring and follow-up, and limiting dispersal of invasive plant seed into burned areas. General recommendations for preventing postfire establishment and spread of invasive plants include:
- Incorporate cost of weed prevention and management into fire rehabilitation plans
- Acquire restoration funding
- Include weed prevention education in fire training
- Minimize soil disturbance and vegetation removal during fire suppression and rehabilitation activities
- Minimize the use of retardants that may alter soil nutrient availability, such as those containing nitrogen and phosphorus
- Avoid areas dominated by high priority invasive plants when locating firelines, monitoring camps, staging areas, and helibases
- Clean equipment and vehicles prior to entering burned areas
- Regulate or prevent human and livestock entry into burned areas until desirable site vegetation has recovered sufficiently to resist invasion by undesirable vegetation
- Monitor burned areas and areas of significant disturbance or traffic from management activity
- Detect weeds early and eradicate before vegetative spread and/or seed dispersal
- Eradicate small patches and contain or control large infestations within or adjacent to the burned area
- Reestablish vegetation on bare ground as soon as possible
- Avoid use of fertilizers in postfire rehabilitation and restoration
- Use only certified weed-free seed mixes when revegetation is necessary
For more detailed information on these topics, see the following publications: [2,6,27,94].
Use of prescribed fire as a control agent: Prescribed fire does not appear to be an effective method for controlling orange hawkweed. Though no studies have used prescribed fire specifically to control orange hawkweed, its establishment following prescribed fire in New Brunswick [29], Ontario [90], and British Columbia [30], and its presence in burned but not unburned sites in Michigan [70], suggest that prescribed fire may encourage orange hawkweed establishment.
Orange hawkweed is mostly apomictic. In New Zealand, most (93.8%) orange hawkweed seed was produced without fertilization [48]. It occasionally produces seed through pollination [12]. Orange hawkweed is pollinated by wind [33] and is visited by insects. On the Upper Peninsula of Michigan, orange hawkweed was an important source of pollen for bees (Megachile relativa and M. inermis) [86]. In Maine, orange hawkweed was visited by bumblebees (Bombus spp.), though the author noted that orange hawkweed offered minute quantities of nectar [34]. It was visited by nectar-collecting yellowbanded bumble bees (B. terricola) in old fields in eastern Ontario [71]. Orange hawkweed was visited by several butterfly species in Michigan [101], and was identified as a nectar species for the Karner blue butterfly in Wisconsin [47].
More info for the term: fire regime
Fuels: As of this writing (2010) there was no information available regarding the fuels characteristics of orange hawkweed.
FIRE REGIMES: It is not known what fire regime orange hawkweed is best adapted to. In North America, orange hawkweed occurs in a wide variety of plant communities, and consequently, a range of FIRE REGIMES. See the Fire Regime Table for further information on FIRE REGIMES of vegetation communities in which orange hawkweed may occur.
Orange hawkweed seedlings establish in the spring [12]. On the Upper Peninsula of Michigan, orange hawkweed flowering was influenced by precipitation [86]. Flowering dates range from May to October in different parts of its North American range.
Month of flowering for orange hawkweed in different parts of its North American range | |
Location | Month |
Alaska | mid-July to October [35] |
Connecticut | June [4] |
Illinois | June to July [66] |
Maine | August to mid-September [33] |
Michigan | June [86] |
Minnesota | May to August; peak in June [37] |
New England | June to August [60] |
North and South Carolina | May to July [72] |
Virginia | May to July [110] |
West Virginia | June to July [85] |
Nova Scotia | June to July [76] |
A weed management guide reports that orange hawkweed seeds lack an after-ripening period and may germinate as soon as they are released from the parent plant [108] (see Germination). Stolons elongate through the summer, forming daughter rosettes at their tips. The stolons die as roots anchor daughter rosettes, and the young plants become independent of the mother plant [12]. After flowering, the supporting rosette dies [82]. New plants sprout each year from rhizomes [12].
More info for the terms: cover, forbs, prescribed fire, severity, wildfire
Fire adaptations: Orange hawkweed exhibits some characteristics that make it adapted to surviving and establishing after fire. It is rhizomatous [16,26,51,107,108], and it is likely that rhizomes below the soil surface survive fire. It reportedly sprouts from stolons and rhizomes after mechanical disturbance [105], and sprouted following herbicide application in Japan [88]. Orange hawkweed seeds have the potential for long-distance seed dispersal, and seeds reportedly persist in the seed bank for at least 7 years. Seedling establishment and plant growth seem to be favored by disturbance and high-light conditions (see Successional Status).
Plant response to fire: Several studies document orange hawkweed occurring in areas burned by wildfire [43,80,107] or prescribed fire [1,29,30,70,90], but to date (2010), a lack of details about fire characteristics, pre- and postfire vegetation, and orange hawkweed response limit the inferences that can be made from these studies. The limited information available suggests that fire may facilitate orange hawkweed establishment and spread.
It is not clear whether fire increases the abundance of orange hawkweed. An Australian government publication reports that existing orange hawkweed populations spread following a January wildfire [105]. Two years after prescribed fire in logged jack pine-red pine forest in northern Lower Michigan, orange hawkweed was one of several forbs commonly found in the understory [1], but its abundance prior to the fire was not reported.
Some studies have documented orange hawkweed establishing after fire in sites where it was not found previously. In eastern Ontario, orange hawkweed was found in a jack pine clearcut within 2 years of prescribed burning. It was not detected in the stands prior to fire [90]. In New Brunswick, a mixed deciduous-coniferous woodlot was clearcut, left untreated for a year, then burned in April for 2 consecutive years to encourage low sweet blueberry (Vaccinium angustifolium) and velvetleaf blueberry (V. myrtilloides) production. June vegetation surveys showed that orange hawkweed was not present prior to treatments, in the year between clearcutting and burning, or in the 1st year after fire. Four orange hawkweed stems were detected 2 months after the 2nd fire. The author suggested that orange hawkweed established via wind-dispersed seed [29].
Orange hawkweed was detected in surveys of 3 managed coniferous forest stands in British Columbia. Prior to treatment, the forests largely contained hybrid spruce (P. engelmannii × P. glauca). Stands were clearcut in the winter and burned the following autumn. Fire was of moderate severity and generally consumed all fine fuels but exposed little mineral soil. Stands were planted with lodgepole pine and/or hybrid spruce the year after fire. Vegetation was sampled prior to treatments and for 10 years afterward. Orange hawkweed was not detected prior to burning or in surveys 1, 2, 3, and 5 years after fire, but it was detected at low levels (0.02% mean cover) 10 years after fire on all 3 sites [30].
One study documented orange hawkweed in burned areas but not in unburned plots. It was detected after both single and multiple low-severity spring prescribed fires in a red pine and eastern white pine plantation in Michigan's southwestern Lower Peninsula. Fire conditions are available in the Research Project Summary of this study. In study plots burned once, the average cover of orange hawkweed 4 growing seasons after fire was 0.33%. In study plots burned biennially, its average cover 2 growing seasons after the 2nd fire was 0.07%, and it did not occur the first growing season after the 3rd fire. It was not present in unburned plots [70].
The combination of fire and other disturbances may increase the potential for orange hawkweed establishment. In northwestern Montana, orange hawkweed was studied in mountain meadows and 3 types of successional lodgepole pine forests: 1) logged, 2) burned by wildfire [43] 12 years previously, and 3) burned by wildfire 12 years previously [42] and then salvage-logged. Descriptions of the wildfire or logging treatments were not reported. Orange hawkweed had the highest probability of detection on burned and salvage-logged sites (P=0.002), which the authors attributed to relatively low levels of "competitive" interactions with other plants and high levels of sunlight and disturbance. However, it was not clear that disturbance was the only factor influencing orange hawkweed establishment, because orange hawkweed had a higher likelihood of establishment in mountain meadows than the 2 other disturbed cover types [43].
More info for the terms: geophyte, ground residual colonizer, initial off-site colonizer, rhizome, root crown, secondary colonizer
POSTFIRE REGENERATION STRATEGY [83]:
Surface rhizome and/or a chamaephytic root crown in organic soil or on soil surface
Rhizomatous herb, rhizome in soil
Geophyte, growing points deep in soil
Ground residual colonizer (on site, initial community)
Initial off-site colonizer (off site, initial community)
Secondary colonizer (on- or off-site seed sources)
Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 15
Species With Barcodes: 1