BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Calluna vulgaris | Heather 



GENERAL BOTANICAL CHARACTERISTICS : 
Heather is an evergreen ascending shrub, usually reaching 3.3 feet (1 m)
in height [7,11,41].  Growth form varies from low and sparse to dense
and bushy [22].  The opposite leaves are 0.08 to 0.16 inches (0.2-0.4
cm) long, and flowers are in axillary or terminal racemes [7,11,41].
The root system is lateral and mostly buried within the top 4 inches (10
cm) of soil [13,34].  On poorly drained sites, roots may extend to 8
inches (20 cm) below ground [34].  Young plants have a taproot that is
later obscured by increased growth and branching of lateral roots.  A
surface mat is formed by adventitious roots and fine branches of the
main root system [13].




RAUNKIAER LIFE FORM : 
   Phanerophyte
   Chamaephyte


REGENERATION PROCESSES : 
Heather reproduces from both seed and vegetative growth from stem bases
[6,10,44].

Heather seeds are small and are dispersed by wind or animals [6,25,45].
Seeds rarely germinate without exposure to light [6,25].  They show poor
germination on moss or lichen mats, possibly due to light deprivation
from the moss or lichen cover.  However, a moss carpet has a positive
effect on seedling performance.  Seedlings established on moss grow
faster and reproduce earlier than seedlings growing on bare ground.
Heather seed germination is better on mineral than organic soil and on
consolidated than loose substrates.  Seeds do not germinate under
waterlogged conditions [6].  Germination increases when seeds are
heat-treated at temperatures of 104 to 176 degrees Fahrenheit (40-80 deg
C) for 1 minute.  Exposure to temperatures above 248 degrees Fahrenheit
(120 deg C) for more than 30 seconds decreases germination rates, and
temperatures exceeding 392 degrees Fahrenheit (200 deg C) kill heather
seeds [21].  Heather establishes large soil seedbanks [8].  Seeds are
usually evenly distributed in the top 2 inches (5 cm) of soil [27].
They may remain viable for over 100 years [25].
 
Sprouting from the stem bases most often occurs in stands between 6 and
10 years of age and decreases in stands over 15 years old [8].  Old
degenerate stands of heather may reproduce by layering [26].

On dry heaths or moors, heather generally has a life span of about 30 to
40 years and communities are usually even-aged.  In these habitats, the
life cycle occurs in four distinct phases.  In the pioneer stage (0-6
years), heather establishes and grows vertically from the apex.  During
the building stage (6-14 years), the plant grows laterally and forms a
dense, intertwining canopy with little light penetration.  In the mature
stage (14-25 years), lateral growth slows and the plant thins out in the
center.  In the degenerate stage (25 or more years), central branches
collapse and die, leaving a gap in the middle of the plant.  The pioneer
stage is characterized by low overall biomass and high productivity; the
building stage by high biomass and high productivity; and the mature and
degenerate stages by high biomass and declining productivity [10].

In wet bog communities, heather does not undergo a phasic life cycle.
An uneven-age structure of aboveground stems develops due to the
constant burial of stems by sphagnum mosses (Sphagnum spp.) [16].
Sphagnum grows over the decumbent heather stems, leaving only young
shoots above ground.  The older parts of the stem are increasingly
filled with heartwood and eventually become nonfunctional.  The
uneven-aged "stem population" is constantly rejuvenated so that the mean
age of aboveground shoots is about 12 years and the maximum age rarely
exceeds 22 years [17].  A degenerate stage does not occur [16].


SITE CHARACTERISTICS : 
Heather is found on nutrient-poor, acidic soils in open areas [20].  It
occurs in dry fields [41], wet bogs [16,24,43], dry heathlands or moors
[10,18,35], clearings in pine (Pinus spp.)-birch forests [10,43], oak
(Quercus spp.) woodlands [10], and above treeline [10,12].




SUCCESSIONAL STATUS : 
Facultative Seral Species

Heather is a slow-growing, early successional shrub [20].  It is present
after logging in Scotch pine and Norway spruce stands in Sweden [2] and
Finland [37].  Heather is highly intolerant of shade [15,20].

In the absence of fire, heather-dominated heaths or moors are replaced
by birch and Scotch pine woodland [15,20], and in some areas by bracken
fern [32].  In wet bogs, heather maintains a "steady state" without
disturbance [16,17].


SEASONAL DEVELOPMENT : 
In North America heather flowers from July to November [7].

Related categories for Species: Calluna vulgaris | Heather