FIRE EFFECTS
SPECIES: Calluna vulgaris | Heather 



IMMEDIATE FIRE EFFECT ON PLANT : 
Exposure to temperatures greater than 932 degrees Fahrenheit (500 deg C)
for more than 1 minute is lethal to heather whatever its age [8].
Severe fires may kill seeds [30].  Light to moderately severe fires may
top-kill heather but usually do not damage stem bases or destroy seeds [25].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
The response of heather to fire is highly variable and is dependent on
(1) the habitat that is burned (wet bog or dry heath), (2) the phase the
heather is in (pioneer, building, mature, degenerate), and (3) the
temperature and duration of the fire.  The severity of grazing on young
heather shoots after fire may also affect their response [36].

Most fires that occur in pioneer or building phase stands in dry heaths
are light to moderately severe.  Regeneration after these fires is by
sprouting from stem bases protected from the heat by litter and organic
soil horizons, and from germination of seeds stored in seedbanks [25].
  
Severe fires which occur due to accumulation of fuel in old or very dry
stands may kill stem bases.  In such cases, regeneration is from seeds
alone, and is much slower than vegetative growth [10,25,28].  If seeds
are killed by severe fire, establishment depends on seed dispersal from
adjacent unburned areas [30].  Severely burned areas may remain bare for
70 years or more [30], or a moss or lichen mat may form which will
inhibit germination of heather seeds [3,30].
 


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
Most heaths dominated by heather are a product of interference by humans
and were historically preceded by forest [30].  In western Europe,
burning at regular intervals has been the principle land management
practice for heaths for over 200 years and has resulted in the
development of pure heather stands over vast tracts of land [17,29,31].
Heaths have been maintained for sheep and red grouse, both of which are
economically important.  When managing red grouse habitat, heather is
burned to provide a mosaic of stands with diverse ages, heights, and
densities [31,35].  Heaths are not burned after March due to breeding
and nesting [47].

In dry heaths of western Europe, fire is used to prevent tree invasion
[36], maintain a balance between young and old heather shoots, and
maintain heather in the building phase at the expense of other species
[17].  Dominance of heather on these heaths is important because it is
often the most productive and nutritious species found on dry, infertile
heath soils [10].  Heather production greatly exceeds heather
consumption by herbivores, resulting in a large accumulation of wood and
litter.  Decomposition is slow in the cool, wet climate and acid soils
of dry heaths, so a deep layer of plant litter and humus forms.  Fire
removes the dead wood and litter.  If burning takes place when the
vegetation is too dry or in old stands with large accumulations of dead
woody material, stem bases may be killed.  Temperatures above 1,112
degress Fahrenheit (600 deg C) increase the loss of nutrients,
especially nitrogen and phosphorous, which are often already deficient
in the nutrient-poor soils that heather grows in [17].

A fire interval of approximately 15 years has been suggested for the
management of heather in heathlands at low to middle altitudes.  This
interval maintains heather in its competitive building phase, allowing
it to outcompete other species [10,35].  If intervals are longer than 15
years, the heather may be too old to sprout from stem bases or fires may
be too severe.  This may lead to an extended period where the
competitive vigor of heather is low, allowing the invasion of bracken
fern or other undesirable species [10].  Since height is an indicator of
stand phase, it can also be used as a factor in determining appropriate
fire intervals.  It has been suggested that heather be burned before it
reaches 12 inches (30 cm) [19]; heather more than 16 inches (40 cm) tall
often burns very severely and is thus seldom targeted for prescribed
fire [30].  A well-managed fire removes most of the aerial vegetation
while still permitting vigorous vegetative regeneration [10,30].
Temperatures of about 752 degrees Fahrenheit (400 deg C) in the canopy
and less than 392 degrees Fahrenheit (200 deg C) at the soil surface are
optimal [10].  Moderate heat may stimulate germination of seeds [31].
 
Fire management of heather in wet bogs produces inconsistent results
[10,16].  Frequent burning of wet bogs in Ireland has in some cases led
to the replacement of heather by deciduous species.  This in turn has
resulted in an increased amount of litter produced yearly and a lower
stocking capacity for sheep in winter.  To maintain heather, areas can
be burned in long rotations [24].  Longer intervals between fires (about
20 years) are also suggested for the management of wet bogs in Great
Britain.  Frequent burning of heather there temporarily increases the
availability of young shoots, but the resulting community is dominated
by sheathed cottonsedge or moor-grass rather than heather.  Burning may
not be required at all since heather remains in a "steady state" in wet
bog habitats [16].

Related categories for Species: Calluna vulgaris | Heather