FIRE EFFECTS
SPECIES: Vaccinium myrtillus | Dwarf Bilberry 



IMMEDIATE FIRE EFFECT ON PLANT : 
Portions of stem bases occasionally survive light fires.  Underground
regenerative structures of dwarf bilberry generally survive all but
extremely hot fires [90].  Rhizomes, which occur at depths of 0.24 to
1.2 inches (6-30 mm) [41,90], can survive fires in which soil surface
temperatures reach 820 degrees F (438 degrees C) [90].  However,
rhizomes are sometimes destroyed on severely burned sites [90].

Seeds of most Vacciniums are of short viability and are readily killed
by heat [64].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Vegetative response:  Dwarf bilberry commonly sprouts from underground
rhizomes or, when damage is less severe, from axillary buds located at
the stem base [62,90].  Sprouting ability appears closely related to
fire intensity and severity [62].  Dwarf bilberry generally sprouts
following all but hot fires [90].  A Colorado study suggests that
although postfire canopy cover is typically high on lightly burned
sites, this shrub may be virtually eliminated on severely burned areas
[109].  Postfire response is generally best in protected microsites or
on lightly burned areas [78,90].

Clonal vigor is often enhanced by fire.  Old, large, decadent clones are
often broken up by fire [38].  Surviving portions serve as isolated
centers of regeneration which give rise to the development of vigorous
daughter clones [81].  

Seed:  Seedlings are rarely observed on burned sites [90].  Although
some researchers consider dwarf bilberry to be a seed banker, adequate
documentation is lacking [See Regeneration].  Birds and mammals may
carry some seed to burned sites.

Postfire response:  Vegetative expansion of dwarf bilberry may be rapid
after fire, particularly where competition is light [81].  Sprouting may
be evident within a few months after fires in which surface soil
temperatures reached as high as 820 degrees F (438 degrees C).  In
forests of northern Sweden, preburn cover can be reached within a few
years.  However, where underground rhizomes are destroyed by fire,
recovery may take a "very long time" [90].  On burned and clearcut old
growth forests of west-central Montana, dwarf bilberry had not attained
preburned biomass within 10 to 14 years after disturbance [78].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Fire temperature:  The effect of temperature on the sprouting ability of
dwarf bilberry in Scotland was documented as follows after 17 months of
regrowth [62]:

                        aboveground temperatures
                        (degrees C for 2 minutes)
                       
                        400          600           800

mean # sprouts/plant    180           51            22
mean % cover            133           68            16
mean height (cm)         22           17            14
mean biomass (g)         85           30             3


FIRE MANAGEMENT CONSIDERATIONS : 
Wildlife:  Evidence suggests that fire suppression may be having an
adverse impact on bear habitat in some areas [102,110].  Once-productive
berry fields are being invaded by conifers.  Since plants beneath a
forest canopy generally produce few berries, fruit production has been
steadily declining in many areas [65].  Berry fields can be treated with
fire if maintenance or enhancement of berry crops is a prime management
objective.  Logging treatments which include severe soil scarification
or slash burns may also reduce berry production.  Even where timber
harvest favors berry production, lack of cover in early years can limit
bear use.  Wildfires often create diverse habitat mosaics which
incorporate elements of hiding cover and favor bear use [102].

Prescribed fire:  Flower buds tend to be more numerous on new shoots,
and periodic removal of old shoots can increase flower production in
Vacciniums.  Prescribed fire has long been used to rejuvenate commercial
low sweet blueberry (V. angustifolium) fields and to increase overall
fruit production [64].  Prescribed fires, particularly those conducted
during the spring when soil moisture is high, may increase berry
production for wildlife species.  Little research has been conducted on
dwarf bilberry, although the use of prescribed fire has been evaluated
with respect to blue and globe huckleberries [64,65] [see the VACMEM
write-up].
 
Fuels:  A dwarf bilberry understory partially supports fine fuels such
as needle litter and small twigs and produces a more optimally aerated
fuel bed.  Estimated fuel loading of dwarf bilberry has been established
for lodgepole pine forests of the southern Rocky Mountains [2].

Timber harvest:  In spruce-fir forests of the southern Rocky Mountains
of New Mexico, forest regeneration after fire may be most rapid in cover
types dominated by Vacciniums such as dwarf bilberry [27].

Related categories for Species: Vaccinium myrtillus | Dwarf Bilberry