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Species
Ulex europaeus L.
IUCN
NCBI
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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
More info for the term: shrub
KUCHLER [47] PLANT ASSOCIATIONS:
K002 Cedar-hemlock-Douglas-fir forest
K005 Mixed conifer forest
K006 Redwood forest
K010 Ponderosa shrub forest
K012 Douglas-fir forest
K026 Oregon oakwoods
K028 Mosaic of K002 and K026
K029 California mixed evergreen forest
K030 California oakwoods
K033 Chaparral
K034 Montane chaparral
K035 Coastal sagebrush
K036 Mosaic of K030 and K035
K048 California steppe
Barcode of Life Data Systems (BOLDS) Stats
Public Records: 9
Specimens with Barcodes: 9
Species With Barcodes: 1
Gorse is native to central and western Europe and the British Isles, where it is an important component of native heathland vegetation (see Habitat Types and Plant Communities) ([37,45,70] and references therein). Gorse also occurs on abandoned farm land and disturbed forests in parts of its native range ([70] and references therein).
Introduced to the eastern U.S. as an ornamental and hedge plant in the early 1800s, gorse established outside cultivation by 1900 [49,50]. It now occurs along the Atlantic coast from Virginia to Massachusetts. Gorse was introduced as an ornamental in Oregon in the late 19th century, and has since spread widely in coastal areas from California to British Columbia and on 2 Hawaiian islands ([15,26,32,37,70] and references therein). It has been reported in the northern Sierra Nevada foothills and in every coastal county in California, from Santa Cruz to Del Norte, although sparingly in southern California [33,37]. Plants database provides a state distribution map of gorse.
Gorse was introduced to Australia and New Zealand in the mid-19th century for domestic sheep forage and hedges, and by 1900 was declared a noxious weed in those countries. It now occurs in most temperate areas of the world, and is considered a weed in Chile, Iran, Italy, Poland, northwest Spain, and Tasmania ([32,37,45,70] and references therein). Much of the literature on the biology, ecology, and management of gorse comes from New Zealand.
The following lists include vegetation types in which gorse is known or thought to be potentially invasive, based on reported occurrence and biological tolerances to site conditions. Precise distribution information is limited, especially in eastern North America; therefore, these lists are not exhaustive.
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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):
ECOSYSTEMS [27]:
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES27 Redwood
FRES28 Western hardwoods
FRES34 Chaparral-mountain shrub
FRES42 Annual grasslands
Red List Criteria
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | © International Union for Conservation of Nature and Natural Resources |
Source | http://www.iucnredlist.org/apps/redlist/details/19891755 |
"Notes: Western Ghats, High Altitude, Native of Europe"
In Great Britain and/or Ireland:
Foodplant / saprobe
effuse, superficial colony of Acrodontium dematiaceous anamorph of Acrodontium echinulatum is saprobic on dead branch of Ulex europaeus
Foodplant / miner
larva of Agromyza johannae mines leaf? of Ulex europaeus
Other: unusual host/prey
Foodplant / gall
larva of Apion atratulum causes gall of young stem of Ulex europaeus
Foodplant / gall
larva of Apion scutellare causes gall of stem of Ulex europaeus
Foodplant / internal feeder
communal larva of Apion ulicis feeds within pod of Ulex europaeus
Foodplant / sap sucker
nymph of Asciodema obsoleta sucks sap of Ulex europaeus
Foodplant / saprobe
gregarious, immersed, black pycnidium of Ascochyta coelomycetous anamorph of Ascochyta ulicis is saprobic on dead branchlet of Ulex europaeus
Remarks: season: 5-6
Foodplant / saprobe
fruitbody of Auricularia mesenterica is saprobic on dead, decayed wood of Ulex europaeus
Foodplant / saprobe
fruitbody of Basidiodendron radians is saprobic on dead woody stem of Ulex europaeus
Foodplant / feeds on
adult of Bruchidius varius feeds on pollen? of Ulex europaeus
Remarks: season: (late 7-early 10, late 4)5-6
Plant / resting place / on
adult of Bruchus atomarius may be found on Ulex europaeus
Plant / associate
adult of Bruchus rufipes is associated with Ulex europaeus
Remarks: season: (late 3-)5-6(-11)
Foodplant / saprobe
fruitbody of Byssomerulius corium is saprobic on fallen, decayed wood of Ulex europaeus
Plant / associate
Cardiastethus fasciiventris is associated with Ulex europaeus
Foodplant / mycorrhiza
fruitbody of Coltricia perennis is mycorrhizal with live root of Ulex europaeus
Foodplant / feeds on
erumpent pycnidium of Coniothyrium coelomycetous anamorph of Coniothyrium sphaerospermum feeds on spine of Ulex europaeus
Remarks: season: 6-11
Foodplant / saprobe
apothecium of Crocicreas complicatum is saprobic on wood of Ulex europaeus
Remarks: season: 1-3
Foodplant / saprobe
effuse, superficial colony of Dactylaria anamorph of Dactylaria scolecospora is saprobic on dead branch of Ulex europaeus
Foodplant / saprobe
pulvinate, erumpent or superficial stroma of Daldinia fissa is saprobic on burnt branch of Ulex europaeus
Foodplant / saprobe
fruitbody of Dendrothele commixta is saprobic on dead, attached twig of Ulex europaeus
Foodplant / sap sucker
nymph of Dictyonota strichnocera sucks sap of Ulex europaeus
Foodplant / saprobe
effuse colony of Diplocladiella dematiaceous anamorph of Diplocladiella scalaroides is saprobic on dead wood of Ulex europaeus
Plant / associate
apothecium of Discinella menziesii is associated with burnt root of Ulex europaeus
Foodplant / parasite
conidial anamorph of Erysiphe trifolii parasitises live Ulex europaeus
Foodplant / saprobe
fruitbody of Flagelloscypha orthospora is saprobic on dead stem (woody) of Ulex europaeus
Other: major host/prey
Foodplant / saprobe
fruitbody of Flammulina velutipes var. velutipes is saprobic on dead wood of Ulex europaeus
Remarks: season: mainly winter
Foodplant / saprobe
fruitbody of Ganoderma australe is saprobic on dead trunk of Ulex europaeus
Foodplant / parasite
fruitbody of Ganoderma lucidum parasitises live stump of Ulex europaeus
Other: unusual host/prey
Foodplant / saprobe
fruitbody of Gloeoporus taxicola is saprobic on dead, decayed wood of Ulex europaeus
Other: unusual host/prey
Foodplant / saprobe
fruitbody of Gymnopilus junonius is saprobic on decayed wood of Ulex europaeus
Other: major host/prey
Foodplant / saprobe
effuse colony of Hansfordia dematiaceous anamorph of Hansfordia pulvinata is saprobic on dead branch of Ulex europaeus
Foodplant / saprobe
fruitbody of Hymenochaete carpatica is saprobic on dead, attached branch of Ulex europaeus
Foodplant / saprobe
fruitbody of Hyphodermella corrugata is saprobic on dead stem of Ulex europaeus
Foodplant / saprobe
fruitbody of Hypochnicium erikssonii is saprobic on dead, fallen, decayed wood of Ulex europaeus
Foodplant / saprobe
fruitbody of Inonotus radiatus is saprobic on dead, standing trunk of Ulex europaeus
Other: unusual host/prey
Foodplant / saprobe
fruitbody of Megalocystidium leucoxanthum is saprobic on dead stem of Ulex europaeus
Other: minor host/prey
Foodplant / saprobe
cyphelloid basidiocarp of Merismodes bresadolae is saprobic on dead, fallen, decayed twig of Ulex europaeus
Foodplant / saprobe
thyriothecium of Microthyrium cytisi var. ulicis is saprobic on dead, bleached, often attached spine of Ulex europaeus
Remarks: season: 2-9
Foodplant / saprobe
apothecium of Mollisiopsis dennisii is saprobic on dry, dead branchlet of Ulex europaeus
Remarks: season: 5-11
Foodplant / feeds on
female of Odontothrips ulicis feeds on live Ulex europaeus
Remarks: season: 1-12
Foodplant / saprobe
fruitbody of Pellidiscus pallidus is saprobic on dead, decayed branch of Ulex europaeus
Foodplant / saprobe
fruitbody of Peniophora incarnata is saprobic on dead, attached branch (small) of Ulex europaeus
Other: major host/prey
Foodplant / saprobe
fruitbody of Peniophora lycii is saprobic on dead, fallen stick of Ulex europaeus
Other: minor host/prey
Foodplant / saprobe
fruitbody of Peniophora violaceolivida is saprobic on dead bark of Ulex europaeus
Foodplant / visitor
adult of Phaedon cochleariae visits for nectar and/or pollen flower (pollen?) of Ulex europaeus
Remarks: season: 5-9
Other: minor host/prey
Foodplant / saprobe
fruitbody of Phanerochaete jose-ferreirae is saprobic on dead, decayed wood of Ulex europaeus
Foodplant / saprobe
fruitbody of Phanerochaete sordida is saprobic on dead stem of Ulex europaeus
Foodplant / saprobe
effuse colony of Phialocephala dematiaceous anamorph of Phialocephala fusca is saprobic on wood of Ulex europaeus
Foodplant / saprobe
pycnidium of Phomopsis coelomycetous anamorph of Phomopsis ligulata is saprobic on dead stem of Ulex europaeus
Remarks: season: 3-6
Foodplant / feeds on
Platycranus bicolor feeds on Ulex europaeus
Foodplant / saprobe
fruitbody of Polyporus tuberaster is saprobic on dead, fallen branch of Ulex europaeus
Foodplant / saprobe
fruitbody of Resupinatus applicatus is saprobic on dead, decayed wood of Ulex europaeus
Other: minor host/prey
Foodplant / saprobe
fruitbody of Resupinatus trichotis is saprobic on dead, attached branch (small) of Ulex europaeus
Other: minor host/prey
Foodplant / saprobe
fruitbody of Schizopora flavipora is saprobic on dead, decayed stem of Ulex europaeus
Foodplant / saprobe
fruitbody of Scopuloides hydnoides is saprobic on dead, wet, decayed stem of Ulex europaeus
Other: unusual host/prey
Foodplant / saprobe
pycnidium of Septoria coelomycetous anamorph of Septoria slaptoniensis is saprobic on dead leaf of Ulex europaeus
Remarks: season: 6
Foodplant / feeds on
larva of Sericothrips staphylinus feeds on live flower of Ulex europaeus
Foodplant / feeds on
larva of Sitona regensteinensis feeds on Ulex europaeus
Foodplant / feeds on
larva of Sitona striatellus feeds on Ulex europaeus
Other: major host/prey
Foodplant / saprobe
fruitbody of Skeletocutis nivea is saprobic on dead, fallen, decayed stick of Ulex europaeus
Other: minor host/prey
Foodplant / saprobe
effuse colony of Sporidesmiella dematiaceous anamorph of Sporidesmiella claviformis is saprobic on dead twig of Ulex europaeus
Foodplant / saprobe
effuse colony of Sporidesmium dematiaceous anamorph of Sporidesmium cambrense is saprobic on dead branch of Ulex europaeus
Remarks: season: 3
Foodplant / saprobe
effuse colony of Sporidesmium dematiaceous anamorph of Sporidesmium cymbispermum is saprobic on dead branch of Ulex europaeus
Foodplant / saprobe
fruitbody of Steccherinum ochraceum is saprobic on dead, fallen, decayed Ulex europaeus
Other: minor host/prey
Foodplant / saprobe
fruitbody of Stereum rameale is saprobic on dead, fallen, decayed stick of Ulex europaeus
Other: minor host/prey
Foodplant / saprobe
fruitbody of Terana caerulea is saprobic on dead, decayed wood of Ulex europaeus
Other: minor host/prey
Foodplant / feeds on
female of Thrips flavus feeds on live flower of Ulex europaeus
Remarks: season: 3-10
Foodplant / saprobe
fruitbody of Trametes hirsuta is saprobic on dead stem of Ulex europaeus
Other: unusual host/prey
Foodplant / saprobe
fruitbody of Trametes pubescens is saprobic on burnt stem of Ulex europaeus
Other: minor host/prey
Plant / associate
basidiocarp of Tremella exigua is associated with dying stem of Ulex europaeus
Other: major host/prey
Plant / associate
basidiocarp of Tremella mesenterica is associated with dead, attached stick of Ulex europaeus
Other: major host/prey
Foodplant / saprobe
apothecium of Venturiocistella ulicicola is saprobic on burnt branch of Ulex europaeus
Remarks: season: 11
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | BioImages, BioImages - the Virtual Fieldguide (UK) |
Source | http://www.bioimages.org.uk/html/Ulex_europaeus.htm |
Canada
Rounded National Status Rank: NNA - Not Applicable
United States
Rounded National Status Rank: NNA - Not Applicable
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | NatureServe |
Source | http://explorer.natureserve.org/servlet/NatureServe?searchName=Ulex+europaeus |
Ulex europaeus is native to Europe (Corsica, France, Germany, Great Britain, Ireland, Italy, Netherlands, Portugal, Spain and Switzerland), and it has been introduced in other countries in Europe, north and south America, Africa, New Zealand and Australia.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | © International Union for Conservation of Nature and Natural Resources |
Source | http://www.iucnredlist.org/apps/redlist/details/19891755 |
More info for the terms: cover, extreme fire behavior, fern, fire management, fire severity, fuel, heath, litter, low-severity fire, phenology, prescribed fire, severity, shrub, shrubs, tree, wildfire
Fire as a control agent: Fire alone will not likely control gorse populations, as it typically results in regeneration of gorse by sprouting and by seedling establishment ( see Plant Response to Fire). Additionally, a review and simulation model presented by Rees and Hill [69] suggests that it takes several years for gorse stands to develop enough litter and dry stems to allow a fire to burn; and a single fire can allow the establishment of a stand that can persist for 30 years and develop a substantial seed bank that could persist for even longer (see Seed banking). However, burning has been used to manage gorse in many areas for decades. A review by King and others [45] suggests that, if correctly timed, burning will reduce gorse biomass, reduce the soil seed bank, destroy seeds still on the plants, kill seedlings, and reduce the number of years subsequent treatments will be needed to exhaust the seed bank.
Fire is often used to remove gorse biomass. However, burning gorse is potentially dangerous, as a stand of gorse can present a serious fire hazard under some conditions (Amme 1983, unpublished report cited by [37]) (see Fire hazard potential). Air quality regulations and issues of public safety on nearby rights-of-way may also limit the use of prescribed fire for gorse control. For effective and safe burning treatments, plan the burn to coincide with times of low fire risk. Consult with local fire department officials to plan the logistical details of the burn including appropriate weather conditions and safety precautions. Because of the potential hazards, King and others [45] recommend using fire for gorse management only in areas too large for manual or mechanical means. Gorse root crowns that are not destroyed in the burn will sprout unless physically removed or killed. Resprouts will not produce seed for at least a year [97], and may be dug out or removed with a weed wrench or killed with herbicides applied within about 6 months after the burn. Moist soil facilitates removal of burned gorse [45].
Fire has been used to reduce numbers of gorse seed in the soil, primarily through the flush of germination that occurs following burning (see Plant Response to Fire). Gorse seedlings that emerge after fire must also be controlled with repeated burns or other follow-up treatment annually until the seed bank is depleted. With reduced seedling survival, burning gorse-infested sites about every 5 years may reduce gorse abundance ([37,69], and references therein). This approach is probably only effective in plant communities adapted to frequent fires. Native shrubs and trees should be planted after burning if native vegetation is not vigorous enough for reestablishment. Native vegetation may be able to outcompete the gorse with continued monitoring and eradication of newly established seedlings ([12,45], and references therein).
The use of fire in conjunction with biological control is complicated because fire is likely to kill biological control agents ([45,69], and references therein). Grazing by goats for 2 to 3 years after fire has been shown to reduce gorse populations to negligible levels in pastures (Radcliffe 1985, as cited by [12]). Gorse regrowth was grazed extensively after fire in heathlands in England (Tubbs 1974, as cited by [70]).
The majority of literature on the use of fire to control gorse comes from New Zealand, where gorse thickets are cleared to make way for planting trees. These approaches usually include an intensive herbicide regime in combination with prescribed burning. Burning alone rarely kills established gorse plants, and burned branches are often left standing, obstructing planters. Herbicides and/or mechanical crushing may be used several months before burning to desiccate gorse biomass or increase surface fuel loads to increase gorse consumption, fire severity, and subsequent mortality of gorse ([3,11,45,98] and references therein). Observations indicate that effective herbicide treatment can also minimize, and ideally eliminate, postfire sprouting in gorse. To achieve this it is necessary to optimize the timing of spray applications, as well as to choose an appropriate chemical and spray formulation. Herbicide is most effective when applied after flowering is complete and the new season's growth averages about 1 inch (2.5 cm) in length [3]. The earlier practice was to spray gorse 3 to 4 months before burning, which tended to result in charred gorse stems rather than complete consumption and also resulted in greater postfire coppicing. Better results are achieved if the desiccant spray is applied 15 months before burning to give a longer period for drying out of the gorse stem ([3,98], and references therein). Ideally, gorse stem moisture content should be reduced below 40% to ensure a burn that will leave the area clear enough for respraying or planting [70]. Rolston and Talbot [74] examined the possibility of reduced basal sprouting in gorse by using preburn spray treatments that kill the whole plant rather than only desiccating foliage. Herbicide treatments desiccated the gorse, some more than others, and some plants were sprouting after herbicide treatment. The degree of stem destruction was positively related to the degree of desiccation before burning (r=0.76). Preburn herbicide treatment reduced postfire sprouting in gorse by 32% to 90%, depending on type and rate of herbicide used [74].
Sometimes gorse can be eradicated with repeated herbicide treatments following burning to kill gorse sprouts and seedlings [11]. Spraying gorse after wildfires in New Zealand resulted in 9% mortality of sprouts, 22% yellow-green sprouts showing no signs of new growth, and 69% of sprouts exhibiting new growth 6 months after spraying. The main effect of postfire spraying was to reduce the average height of postfire sprouts to 6 to 8 inches (15-20 cm) compared with unsprayed areas where sprouts averaged 21 inches (54 cm) [3]. Herbicides may be applied to coincide with the postfire seedling flush and the "natural" seedling flush to be most efficient. After 2 applications of selected herbicides, residual soil seed numbers were reduced to as few as 5% of prefire levels, and 17 months after burning, gorse ground cover was reduced to 3% to 5% (Zabkeiwicz unpublished, as cited by [98]). Studies on developing gorse seedlings have shown that as its physical character changes (i.e. leaves are replaced by spines), its susceptibility to herbicides decreases. Zabkiewicz [97] recommends spraying soon after fire, killing gorse and grass seedlings to maintain bare soil. This may induce further germination of gorse, and those seedlings can then be sprayed. A problem with postburn spraying of gorse in gorse/bracken mixtures is that postfire fern growth intercepts the chemicals intended for gorse [3].
Fire hazard potential: It is commonly reported in the literature that gorse has high concentration of volatile oils in its foliage and branches [15,64] and produces considerable biomass with abundant dead material in the plant's center [13,45,64], such that gorse stands are highly flammable [15,33,45,51,64], burn rapidly and with high intensity [12,24,38,45], and pose a serious fire hazard [13,32,36,64]. Relatively little research is available, however, that examines gorse fuel characteristics, and none from North America.
Gorse occurs in fire-maintained heathland in its native range, where elements of fire risk, fuel biomass, and fuel structure have been studied. As heathlands age, combustible material accumulates and increases fire risk [75]. Fire risk in tall heath, as judged by accumulated biomass, was appreciable 5 to 7 years after low-severity fire and 10 to 15 years after higher severity fire. In tall heath "critical fire-risk threshold" was represented by a biomass of about 50 t/ha and continuous horizontal structure [25]. Hely and Forgeard [31] studied the structure and seasonal moisture characteristics of aboveground biomass in gorse in tall heathland in France for 15 months to assess its fuel characteristics for fire propagation models. Aboveground biomass had a spatially heterogeneous distribution due to the layered pattern of the branches. This pattern creates an internal moisture gradient that decreases from the apex to the base of the plant, and varies according to plant phenology. New, green branches with a high moisture content occur at the top of the plant (upper strata), whereas woody branches with a lower moisture content occur near the ground (lower strata). Dry branches and spines, which produce most of the litter, are homogeneously distributed throughout the pant. Temporally, the layered pattern is homogeneous through the year and thus creates a constant fire risk. Soil organic horizons under gorse are temporally, spatially, and compositionally heterogeneous, and the distance form a plant has a significant influence on the depth distribution of the soil organic horizons [31]. Total phytomass of dead wood increases substantially with plant height, but does not show a seasonal trend [65].
Nunez-Regueira and others [58] measured calorific values (high heating value (HHV) and low heating value (LHV)) and determined flammability of gorse and other vegetation samples taken from shrubland in Spain during different seasons. Heating values (energy released per unit of combustible mass) of gorse were as follows:
Season | HHV (kJ/kg) | LHV (kJ/kg) |
Spring | 20,182.38±64.15 (0.32%) | 5,724.55±24.81 (0.43%) |
Summer | 20,680.74±73.71 (0.36%) | 6,327.94±29.86 (0.47%) |
Fall | 20,950.41±87.82 (0.42%) | 6,901.35±37.33 (0.42%) |
Winter | 20,472.57±81.33 (0.40%) | 5,720.51±30.90 (0.54%) |
Flammability values (according to a model proposed by Valette 1988) were highest in summer and fall, and gorse had the lowest flammability of the species tested [58].
Egunjobi [22] measured biomass distribution in green shoot, dead shoot, stem, and roots of gorse over 3 years, beginning 6 years after fire in New Zealand. Prefire vegetation was dominated by a closed canopy of gorse, 6 feet (2 m) tall, with little light reaching the ground. Average rate of dry matter accumulation in the standing crop (all species included, with gorse dominant at >80% cover) was 11,780 kg/ha in 1966, and 9,790 kg/ha in 1967. Mean annual litter fall in these communities over these 2 years was 8,880 kg/ha. Biomass distribution and energy content in a 7 year old stand (burned in December 1959) were as follows [22]:
Biomass (kg/ha) |
Calorific value (cal/g dry wt) |
Energy content (108 cal/ha) |
|||
Dec-65 | Jun-66 | May-67 | |||
Green shoot | 10,020 | 12,200 | 17,000 | 5,070 | 862 |
Dead shoot | 2,260 | 2,550 | 3,330 | 5,260 | 175 |
Stem | 14,760 | 41,500 | 35,600 | 4,770 | 1,698 |
Root | 4,830 | 9,040 | 9,000 | 4,840 | 436 |
Total | 31,870 | 65,290 | 64,930 | --- | 3,171 |
Maximum frequencies (%) of different plant fractions in each of 3 height classes of gorse (I = 0-30 cm, II = 31-90 cm, III = 91-150 cm) were compared by season in gorse shrubland in northwest Spain [65]:
Spring | Summer | Fall | Winter | |||||||||
Height class | I | II | III | I | II | III | I | II | III | I | II | III |
Plant fractions | ||||||||||||
Green | 76.7 | 62.5 | 78.3 | 86.0 | 81.7 | 36.7 | 69.2 | 49.2 | 57.5 | 76.7 | 41.7 | 44.2 |
Wood | 10.7 | 45.0 | 42.5 | 20.0 | 64.2 | 40.8 | 23.3 | 40.0 | 42.5 | 18.7 | 45.0 | 42.5 |
Reproductive | 30.0 | 42.5 | 50.8 | 0.0 | 1.7 | 1.7 | 0.0 | 0.0 | 0.0 | 0.7 | 5.8 | 8.3 |
Dead | 16.0 | 65.8 | 69.2 | 11.3 | 81.7 | 61.7 | 45.0 | 50.0 | 75.0 | 18.0 | 74.2 | 61.7 |
The only reference to fire behavior in gorse in North America suggests that gorse fueled the wildfire, and was one of the obstacles to control, that burned down the town of Bandon, Oregon, in 1936, killing 13 people [38,52]. Fogarty [24] describes 2 wildfires in New Zealand, where the predominant fuel type was gorse. Both occurred during conditions of "High" forest fire danger, and on steep slopes (30-35 degrees), during strong winds (20-25 km/h). The gorse at both sites was dense enough to restrict firefighter access. The McEwans Fire (6 February, 1994) was on steep slopes and exhibited extreme fire behavior with a head fire spread rate of 4,440 m/h (+ 360 m/h) and a fire line intensity of 60,000 kW/m. This fire burned in 7- to 8-foot (2-2.5 m) tall gorse under 7-year-old pine that had been partially thinned and pruned. Samples from gorse of similar height and cover suggest that available fuel loads were at least 30 t/ha (G. Pearce and L. Fogarty, unpublished data, as cited by [24]). The Montgomery Crescent Fire (1 March 1994) had a rate of spread of 3,400 m/h (+ 550 m/h), and a fire line intensity of greater than 25,000 kW/m. Gorse plants were shorter at the Montgomery fire, and the pre- and postburn fuel measurements indicated that approximately 17 t/ha was consumed by the fire [24].
These fires occurred at the rural/urban interface, and issues of suppression, safety of residents, and firefighters, and other fire management issues are discussed in this report. "While no adequate Fire Behaviour Prediction (FBP) System (Forestry Canada Fire Danger Group 1992) exists for fires burning in gorse, it is apparent from numerous observations and some limited experimental burning (G. Pearce and L. Fogarty, unpublished data, as cited by [24]) that these fuels are exceptionally flammable and capable of sustaining extreme fire behavior at Low to High forest fire danger conditions" in New Zealand [24]. In a survey of firefighter fatalities, injuries, and near misses in New Zealand, at least 20 out of the 34 cases reported involve fire fighters being trapped in dangerous situations because of a fire run or wind change. Over 50% of these fires were in gorse. The author suggests clearing fuels to create at least 130 feet (40 m) of defensible space in the most likely direction of fire spread to increase the probability of house survival on home sites characterized by steep slopes and gorse (Millman 1993, as cited by [24]).
Similarly, in Australia high fire danger occurs in areas where nonnative shrubs form dense, tall, flammable undergrowth below sclerophyll forests. Gorse is a major fire hazard, because of its dense, dry growth from the previous season. When this shrub layer burns it ignites the sclerophyll tree canopy. Fire in these communities in summer may be impossible to control and is likely to result in a dense sward of seedlings [13].
Effects of gorse fire on other ecosystem properties: In its native range in Spain, researchers have examined the effects of burning heathland dominated by gorse on various ecosystem properties including nutrient inputs and losses, and moisture availability [80,81,82].
Availability of nutrients in ash is governed by temperatures reached during combustion, and by characteristics of vegetation and elements. Elemental analysis of gorse ashes gave the following results [81]:
C(%) | N(%) | Na (mg/g) | K (mg/g) | Ca (mg/g) | Mg (mg/g) | P (mg/g) | pH (1:1000) |
7.35 | 1.11 | 157.66 | 92.15 | 27.52 | 45.12 | 29.20 | 11.10 |
Leaching of nutrients increased with increasing soil-exposure temperature, up to 860 °F (460 °C), then dropped at higher temperatures [81].
In some ecosystems there is concern regarding nutrient losses resulting from frequent fire. Nutrients lost from gorse scrub during burning and subsequent effects on nutrient input and output, through surface and subsurface runoff and soil erosion, were examined. Between 50% and 75% of nutrients contained in plant tissues were lost through combustion, and small amounts (3%) were deposited on the soil surface as ash. During the first rains after burning, nitrogen (N), phosphorus (P), and potassium (K) losses were largely due to sediment transport in surface runoff, while calcium (Ca) and magnesium (Mg) losses were due to both sediment and soluble-form losses (surface and subsurface flow). Nitrogen losses were largely in soluble form. Postfire nutrient inputs to the soil in throughfall were lower than in the control plots for N and K, while the remaining elements differed little between burn and control plots. In general, burning led to clear net losses of nutrients, whereas inputs and outputs were approximately equal in control plots [80].
Soil moisture distribution is modified by fire due to an increase in throughfall with removal of vegetation, an increase in evaporation in the surface soil, and a decrease of transpiration from deep soil layers. Effects of fire on throughfall and soil moisture were evaluated in gorse-dominated heathland in Spain. Throughfall in mature gorse shrubland is about 35% to 50% of gross rainfall. Water volume reaching the soil was significantly increased in burned plots during the first 2 years, where throughfall was 50% higher in burned plots than in control plots. Throughfall then declined gradually until it was similar in both burned and unburned plots by the 4th postfire year. Increased vegetation cover beyond the 4th postfire year did not create further reductions in throughfall. Removal of vegetation cover in gorse scrub by fire mainly affected subsurface water flows. Surface runoff increased after fire but did not entirely account for the increase in throughfall. Overall, soil moisture was higher in burned plots than in unburned plots. Water extraction from deep layers of soil in burned plots was mainly due to gorse sprouting from the root system. Use of the old root system by sprouting vegetation leads to a soil water profile in which 20 months after the fire the soil water is similar in burned and unburned areas [82].