Broom Crowberry & Black Crowberry

Scientific Lit on Broom Crowberry and Black Crowberry especially as related to fire.

On distinguishing Nova Scotia’s 3 spcies of “Crowberry”

There are 3 “crowberries”  in Nova Scotia: Broom Crowberry (Coerma conradii), Black Crowberry (Empetrum nigrum) and Pink Crowberry (Emptrum eamessi). The 3 species require careful observation to distinguish between them when flowers or fruit are not present. The links above are to descriptions of these species by myself (aka JackPine) with many photos, all at NS sites including coastal sites where the three species co-occur.
Alternatively, view these PDFs:
Coerma conradii
Empetrum nigrum
Emptrum eamessi


Rare plants in coastal heathlands: observations on Corema conradii (Empetraceae) and Helianthemum dumosum (Cistaceae) (PDF on ResearchGate)
P.W. Dunwiddie in Rhodora, 92 (1990), pp. 22-26  “The effects of prescribed burning experiments on two rare coastal heathland species are described. Fire killed adult Corema conradii Torr., but resulted in abundant seedling regeneration. Ants may be important vectors in the dispersal of Corema fruits. Following a spring burn, both cover and flowering of Helianthemum dumosum (Bickn.) Fern. increased. Seedlings of this species also were more common, especially where cover of Cladonia lichens was reduced. Occasional fire may be necessary to maintain healthy, reproductive populations of these species.”

The Biology of Corema conradii: Natural History, Reproduction, and Observations of a Post- Fire Seedling Recruitment (PDF available)
Author(s): Christopher T. Martine, David Lubertazzi, Andrew DuBrul
Source: Northeastern Naturalist, Vol. 12, No. 3 (2005), pp. 267-286
Published by: Humboldt Field Research Institute  “Corema conradii (broom-crowberry, Ericaceae) is a rare dioecious shrub that reaches the southern extent of its range in New Jersey. A hot fire burned through one of the most extensive New Jersey populations of this state-endangered species during the summer of 2001, resulting in mortality of nearly all plants in the burned areas. Significant seedling recruitment occurred in the fall of 2002, followed by an even greater seedling emergence the following year. Fire is known to be an important stimulus for seed germination in this species, and fire events are an important component of the life cycle. We report data on seedling emergence as well as present ecological and biological observations of Corema conradii in the unusual coremal habitat of the New Jersey Pine Barrens, and suggest a life cycle model for this understudied species.”

Vulnerable broom crowberry (Corema conradii) benefits from ant seed dispersal in coastal US heathlands (PDF available)
E Hilley, R Thiet – Plant ecology, 2015 – Springer “Relatively little research has been conducted on ant seed dispersal of Corema conradii (broom crowberry), a key constituent of globally threatened coastal heathland ecosystems where fire is part of the disturbance regime. We conducted field studies at Cape Cod National Seashore, MA, USA to better understand the fruiting biology of C. conradii and to explore the benefits of ant seed dispersal. We identified how C. conradii fruit is displayed to foraging ants, determined the ant species that disperse C. conradii fruit, and quantified the distance that ants disperse fruit. We hypothesized that ants would disperse fruit away from C. conradii parent plants that become burn footprints following fire, to ensure seed dispersal to suitable germination sites, where we expected to find higher seedling establishment. We recorded eight ant species dispersing the fruit of C. conradii an average distance of 136 cm (±10.45) (range: 7­641 cm). Two ant species, Aphaenogaster treatae and Formica dolosa, dispersed 60 % of fruit in fruit-baiting experiments, suggesting they may function as primary dispersers in this system. Ants dispersed fruit outside the burn footprints 82 % of the time, and seedlings occurred outside the burn footprints 90 % of the time. Our results suggest that ant seed dispersal confers important reproductive benefits to C. conradii by directing seed dispersal sufficient distances away from parent plants onto suitable substrates for germination after intense, episodic fires.”

Distribution Trends of Rare Plants at the Warren Grove Gunnery Range
Author(s): Walter F. Bien, James R. Spotila and Ted Gordon
Source: Bartonia , 2009, No. 64 (2009), pp. 1-18 “ABSTRACT. We conducted a comprehensive rare plant survey at the Warren Grove Gunnery Range (WGR), Burlington County, New Jersey from July 2004 through August 2006. Although areas outside the Range boundary have a long history of botanical exploration, little information on rare plant occurrences, habitats and distribution exists for WGR. The landscape at WGR is a mosaic of upland and lowland habitats that include sections of the East Pine Plains and the Oswego River Lowlands (ORL)….Natural resource management at WGR appears to successfully protect, promote and conserve habitat for rare plants concurrent with the military mission.” Includes review of fire effects on Corema conradii.

Related to NS

Twenty years of ecological research in Nova Scotia wilderness areas and nature reserves: A review of studies, 2002 to 2022
RP Cameron – Proceedings of the Nova Scotian Institute of Science, 2022 PDF

Species richness, abundance, rarity and environmental gradients in coastal barren vegetation
EC Oberndorfer, JT Lundholm – Biodiversity and Conservation, 2009. PDF




U.S. Fire Effects Information System (FEIS): Empetrum Nigrum

Black crowberry is distributed throughout Alaska, across the Yukon
Territory and Canada to Labrador, Newfoundland, and Greenland.  It
occurs south through New England and the Great Lakes states, as well as
along the Pacific Coast to northern California.  Black crowberry also
has a wide distribution throughout Europe [38,42,47].
Black crowberry is a dominant or codominant in a variety of different
habitats.  It may occur as an understory dominant in open conifer
woodlands with black spruce (Picea mariana), white spruce (P. glauca),
or shore pine (Pinus contorta var. contorta).  Black crowberry can
dominate shrub-types with dwarf birch (Betula nana), willow (Salix
spp.), and ericaceous shrubs in bogs or muskegs and on open, moist
tundra [1,8,33,37,46].

Other commonly associated species include:  paper birch (Betula
papyrifera), quaking aspen (Populus tremuloides), Alaska cedar
(Chamaecyparis nootkatensis), bog birch (Betula glandulosa), Labrador
tea (Ledum glandulosum and L. groenlandicum), various Vaccinium and
Carex species, feathermosses (Hylocomium spp. and Pleurozium spp.),
lichens (Cladonia spp. and Cladina spp.), and sphagnum mosses.

FIRE ECOLOGY OR ADAPTATIONS : Black crowberry generally occurs in communities with long fire intervals or in communities that lack the dry fuel to sustain a fire [7,24,45]. Low growth form and small stems make black crowberry liable to top-kill by fire. Belowground parts are also very susceptible to fire damage because most of them are located near the soil surface [14,35]. Postfire seedlings may arise from seed banks but are not a regular occurrence [24]. Black crowberry can regenerate vegetatively following fire [5,20,39], but this process is slow. Normal or prefire densities may not be reached for 20 to 30 years [24].

PLANT RESPONSE TO FIRE : Black crowberry is slow to recover following fire [5,48,50]. In Labrador, black crowberry decreased significantly in frequency and abundance following fire. Preburn frequency was 61 percent, while postburn frequency was 0 percent after 5 years [14]. It also showed little or no recovery in 2- or 7 year-old burns in the Seward Peninsula, Alaska [35]. In the Wickersham Dome Fire near Fairbanks, Alaska, black crowberry in black spruce stands responded differently in lightly and heavily burned areas. In the lightly burned sites, percent cover was 1.4, 1.1, 0.9, and 1.25 in postfire years 1, 2, 3, and 4, respectively. However, in the heavily burned sites, black crowberry cover was 0 percent in the 4 years immediately following the fire [46].

Page created Nov 2, 2023 by David Patriquin Updates, corrections to follow.