Index of Species Information

SPECIES:  Kalmia angustifolia


SPECIES: Kalmia angustifolia
AUTHORSHIP AND CITATION : Van Deelen, Timothy R. 1991. Kalmia angustifolia. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: [].
ABBREVIATION : KALANG SYNONYMS : Kalmia carolina (Small) Fernald SCS PLANT CODE : KAAN COMMON NAMES : sheep-laurel lambkill sheepkill calfkill dwarf-laurel wicky TAXONOMY : The currently accepted scientific name of sheep-laurel is Kalmia angustifolia L. (Ericaceae). There are no recognized subspecies. Recognized varieties [22] and form [43] include: K. a. var. angustifolia K. a. var. carolina (Small) Fernald K. a. forma candida Fernald Sheep-laurel does not hybridize with other North American Kalmia species [43]. LIFE FORM : Shrub FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


SPECIES: Kalmia angustifolia
GENERAL DISTRIBUTION : Sheep-laurel is found in northeastern North America from Newfoundland and Labrador west through Ontario, south through Michigan, and occasionally as far south as Georgia. It is most common in the eastern Great Lakes region, the St. Lawrence River region, northern New England, and the Maritime Provinces. Sheep-laurel is occasional in the Appalachian Mountains, on the Piedmont Plateau, and on the United States' upper Atlantic Coastal Plain [36,41]. ECOSYSTEMS : FRES10 White - red - jack pine FRES11 Spruce - fir FRES13 Loblolly - shortleaf pine FRES19 Aspen - birch STATES : CT GA ME MD MA MI MN NH NJ NY PA RI VT WI LB NB NF NS ON PE PQ BLM PHYSIOGRAPHIC REGIONS : NO-ENTRY KUCHLER PLANT ASSOCIATIONS : K093 Great Lakes spruce - fir forest K094 Conifer bog K095 Great Lakes pine forest K096 Northeastern spruce - fir forest K106 Northern hardwoods K107 Northern hardwoods - fir forest K108 Northern hardwoods - spruce forest K110 Northeastern oak - pine forest (Quercus-Pinus) SAF COVER TYPES : 1 Jack pine 5 Balsam fir 12 Black spruce 13 Black spruce - tamarack 18 Paper birch 21 Eastern white pine 32 Red spruce 33 Red spruce - balsam fir 35 Paper birch - red spruce - balsam fir 37 Northern white cedar 45 Pitch pine 107 White spruce SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : Sheep-laurel is a common understory shrub in eastern lowland forests. It is characteristically found in coniferous, mixed, and hardwood stands in eastern Canada and the northeastern United States [28,38]. On peatlands, it often occurs in extensive, nearly pure stands known as "heaths" [6]. Sheep-laurel is a common dominant of bog communities in the lower St. Lawrence lowlands [10] and grows in the New Jersey Pine Barrens [11]. Common overstory associates include red spruce (Picea rubens) [2], black spruce (Picea mariana) [8,42], jack pine (Pinus banksiana) [28], quaking aspen (Populus tremuloides), and paper birch (Betula papyrifera) [37]. Understory associates include bog Labrador tea (Ledum groenlandicum), low sweet blueberry (Vaccinium angustifolium), wintergreen (Gaultheria procumbens), sweet fern (Comptonia peregrina) [43], Sphagnum spp., and Cladonia spp. [8,37] Published classification schemes listing sheep-laurel as a dominant or codominant member of a plant associations or community types include: Geographical changes in the vegetation of raised bogs in the bay of Fundy region of Maine and New Brunswick [7] The principal plant associations of the St. Lawrence Valley [9].


SPECIES: Kalmia angustifolia
IMPORTANCE TO LIVESTOCK AND WILDLIFE : Sheep-laurel is poisonous to livestock; hence the common names sheepkill, lambkill, and calfkill [24,36,41]. Toxicity levels, defined as the percent body weight of foliage needed to induce toxic symptoms, are 0.15 percent for sheep, 0.20 percent for cattle, and 0.25 percent for goats [24]. Sheep-laurel also poisons horses. Poisoning typically occurs during the winter when persistent sheep-laurel leaves are the only available vegetation above light snow cover. Poisoning symptoms include salivation, watery eyes, running nose, vomiting with convulsions, and paralysis [43]. Sheep-laurel is not eaten by moose in Newfoundland [39] although it is eaten by grouse [41], and is important winter food for caribou in Ontario [1]. PALATABILITY : Sheep-laurel leaves are tough. Animals that eat them do so only when other forage is unavailable [43]. NUTRITIONAL VALUE : NO-ENTRY COVER VALUE : Sheep-laurel provides nesting sites for willow ptarmigans [43]. VALUE FOR REHABILITATION OF DISTURBED SITES : Although used to reclaim mined peatlands [13], sheep-laurel is little used for reclamation of other sites, so its value on other sites remains unknown. It responds to transplanting by sprouting [17]. It returns very little leaf litter to the soil. Sheep-laurel builds up the raw humus layer through root die-off which may include 20 percent of the root mass greater than 0.33 inch (1 cm) in diameter and account for 9.2 tons of additional humus per acre (907 kg/ha) annually. It returns 19 pounds of nitrogen per acre (28 kg/ha) yearly [6]. Sheep-laurel has a class IV gypsy-moth susceptibility: unfavored or rarely fed upon [20]. OTHER USES AND VALUES : NO-ENTRY OTHER MANAGEMENT CONSIDERATIONS : Sheep-laurel is a serious pest in blueberry fields. Control by fire is usually ineffective [34]. Sheep-laurel has stronger rhizomes and sprout growth than blueberry and requires repeated control [21]. Ten percent of all the low sweet blueberry acreage in the Maritime Provinces requires sheep-laurel herbicide control treatment each year [43]. In addition to outcompeting conifer seedlings for nutrients, light, and space [29], sheep-laurel has an allelopathic effect on conifer seedlings [5,29,39]. The establishment of sheep-laurel-dominated heaths after disturbance may produce soil conditions that prevent conifer seedling establishment [5,6]. Several herbicide treatments have been tested for control of sheep-laurel. Most were difficult to use and ineffective [43].


SPECIES: Kalmia angustifolia
GENERAL BOTANICAL CHARACTERISTICS : Sheep-laurel is a small, branchy, evergreen shrub which reaches 1 to 3 feet (30-90 cm) in height. It has pink, showy, five-part flowers on stalked clusters. The fruit is a small capsule containing many seeds. Capsules may persist on the branches for several years [4,36]. Sheep-laurel forms a well-developed and closely interlacing network of rhizomes. The root system consists of a taproot which may extend to a depth of 3 feet (1 m) [43]. It also has fine roots nearer to the soil surface [6]. Fine root depths vary from 3.5 inches (9 cm) in mineral soil to 12 inches (31 cm) in bogs [14,39]. RAUNKIAER LIFE FORM : Phanerophyte REGENERATION PROCESSES : Reproduction is primarily vegetative. Sheep-laurel plants are clonal and expand laterally. Sprouts grow from dormant buds on rhizomes. Very little is known about sexual reproduction and seedling establishment. Individual stems produce an estimated 7,100 seeds per year. Clones are self-compatible, but seedlings from selfing are less vigorous than seedlings from crossing [43]. SITE CHARACTERISTICS : Sheep-laurel grows on a variety of sites ranging from wet sphagnum bogs to dry jack pine forests. It is frequently found on sites that are very dry during the summer but saturated or flooded during the spring [34]. On peatland, it grows under both oligotrophic and ombrotrophic conditions [3,8]. In the Northeast, sheep-laurel grows in moist conifer woods, pastures, barrens, roadsides, and open thickets [34]. Sheep-laurel typically grows on podzols which have developed under a cold to temperate climate on acidic parent material [43]. On peatland it grows on well-drained peat and peaty podzols. On forested sites sheep-laurel grows on dry, acid, run-out soils; rocky, gravelly soils; sandy loams; and iron-rich, lithosolic, or Ortstein podzols [7,34,36]. Its western range may be limited by high soil pH and lack of moisture [43]. On peatlands in Newfoundland, sheep-laurel grows independent of the mineral soil, taking all of its nutrients from the organic layer. On forested sites it roots in mineral soil [6]. Sheep-laurel grows under a climate regime that is cold and wet for much of the year. Minimum temperatures at the northern limits of its range are -40 degrees Fahrenheit (-40 deg C) [43]. SUCCESSIONAL STATUS : Sheep-laurel is somewhat shade intolerant. Under low light conditions it persists but does not grow appreciably. Overstory removal and increased light trigger release, causing sheep-laurel cover to quickly increase [3]. It is considered early successional in the bog formation sequence, although it may become dominant and arrest succession following bog disturbance by fire or drainage [6]. On frequently disturbed forest sites, most logging practices favor sheep-laurel establishment. Clones may expand and persist for several decades, reducing tree establishment and creating heaths or "Kalmia barrens" [5,6,32]. On undisturbed sites sheep-laurel is replaced by trees such as balsam fir and black spruce [5]. SEASONAL DEVELOPMENT : Sheep-laurel flowers during June and early July. Its fruit ripens between late July and mid-September [23,36,43]. The seeds disperse in early October. New shoot growth begins during late May and early June [43].


SPECIES: Kalmia angustifolia
FIRE ECOLOGY OR ADAPTATIONS : Sheep-laurel sprouts soon after fire [35]. Persistent rhizomes in the soil are protected from all but the most severe fires and allow it to regenerate quickly [15,35]. FIRE REGIMES : 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". POSTFIRE REGENERATION STRATEGY : Small shrub, adventitious-bud root crown


SPECIES: Kalmia angustifolia
IMMEDIATE FIRE EFFECT ON PLANT : Fire kills aerial portions of sheep-laurel stems. Light fires that do not harm the buried rhizomes do not kill the plant. Severe fires that consume the organic layer or sufficiently heat the soil surrounding the rhizomes do kill sheep-laurel [30]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : Sheep-laurel's ability to survive a fire depends on the survival of its rhizomes. Sheep-laurel rhizomes growing in forest mineral soils are relatively shallowly buried and depend on the insulating value of the soil and soil moisture for protection against lethal soil temperatures [16]. On bogs or peatlands, sheep-laurel rhizomes are generally deeper. When wet, these soils offer both insulation and protection from fire. When dry, these organic soils themselves may be consumed, killing the sheep laurel rhizomes [15]. On peatlands, sheep-laurel survives only where the humus layer is not destroyed [30]. PLANT RESPONSE TO FIRE : The immediate postfire response of sheep-laurel is a decrease in frequency and abundance [18]. However, it quickly responds to fire (and cutting) with vigorous sprouting [29]. Fire stimulates the growth of adventitious roots from the burned root stubs and rhizomes near the soil surface [29,35]. Sprouts can be seen soon afterward. In an Ontario study, new shoots were 2 inches (5 cm) tall 2 weeks after a fire, and 6 inches tall (15 cm) 6 weeks after the fire [35]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : Although visible on a site within 2 weeks of a fire, sheep-laurel shows the greatest increase in frequency between postfire year 1 and 2. Its frequency may increase 500 percent and then remain relatively constant for the next 40 years [31]. Regrowth after summer fires is slower than regrowth after spring or fall fires, which shows a strong increase in sprout density. Summer fires coincide with a period of low photosynthate reserves that follows the spring growth spurt [14,17]. Light spring or fall fires encourage prolific growth [31]. In a greenhouse experiment, Mallik [29] compared sheep-laurel shrubs that had been cut or cut and burned with control plants. There was no significant difference between the number and density of new sprouts for the treatments and for the control. Treatment sprouts were more robust, but treatment rhizomes were smaller. Sheep-laurel directs photosynthates to aboveground growth at the expense of belowground growth following disturbance. FIRE MANAGEMENT CONSIDERATIONS : All but the most severe fires enhance the growth of sheep-laurel stands. Permanent control of sheep laurel require fires severe enough to kill the rhizomes; such fires often consume the organic layer of the soil [31]. Managers should note that most sheep-laurel-dominated communities in Nova Scotia are associated with frequent fires. Logging and fire promote heath formation [5]. The high stem density in heaths causes severe fires when they eventually burn. Frequent fires reduce fuel accumulation and, consequently, are less severe [26].


SPECIES: Kalmia angustifolia
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