FIRE EFFECTS
SPECIES: Arctostaphylos uva-ursi | Bearberry 



IMMEDIATE FIRE EFFECT ON PLANT : 
Fire effects vary with the season, severity and intensity of the fire,
site and surface soil characteristics, and the age, location, and vigor
of the plants.  When bearberry is rooted in mineral soil, it can survive
moderate fire [114].  However, when bearberry is rooted in organic soil
horizons, a fire that removes those horizons will kill bearberry
[6,14,39].  If the duff and soil are moist and not completely consumed
by fire, some bearberry root crowns may survive [23].  Rooted stolons
under rocks, moist logs, or in other protected microsites may also
survive [22].  Bearberry plants are sufficiently resistant to ignition
to inhibit fire spread in light, flashy fuels [46,68].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
In a controlled experiment, five bearberry plants were burned at
different temperatures.  Heat treatments lasted about 2 minutes apiece.
Bearberry response was strongest at the middle temperature of 1112
degrees F (600 degrees C).  The number of postfire sprouts after 3
months, and the amount of cover, height of the sprouts, and oven-dry
biomass after 17 months were recorded [86]:

                        Temperature in degrees F (degrees C)
                   752 (400)           1112 (600)          1472 (800)

                  mean  S.E.          mean  S.E.          mean  S.E. 
Sprout numbers     44    20            48    13            26     7
Percent cover      42    15            78    19            45    19
Height (in)         2.4   3.5           2.4   0.4           1.6   0.4
       (cm)         6     9             6     1             4     1
Biomass (oz)        1.1   0.4           1.9   0.5           0.9   0.4
        (g)        30    11            54    15            26    10


PLANT RESPONSE TO FIRE : 
Bearberry sprouts from the root crown and establishes from
seedbank-stored seed after fire [85,114,115,129].  Bearberry seeds have
been reported to survive fire in the upper soil and be stimulated to
germinate by heat from the fire [114].  Rowe [114] suggests that
bearberry may be a shade-intolerant species that stores seed in the
soil.

After fire in heathland, bearberry sprouts vigorously and expands
rapidly [85].  Bearberry reinvades burned sites from adjacent, unburned
vegetation and/or from seed [6,23,39,81,148].  

In boreal forest, bearberry has regenerated from surviving basal sprouts
following fire [115,129].  Full recovery in many areas has been slow
[17,32,120].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Bearberry's response is variable and dependent upon survival of shallow
regenerative organs and seed sources.  Several studies seem to indicate
a slow postfire response with a definite increase in early succession.
Immediate postfire results of a study in Scotland heath were variable.
In one set of plots, seedling establishment during the first 3 years
after a March fire was good [87].  A second set of plots monitored
following the same fire had good vegetative recovery but no seedlings
[88].  Results of a northwestern Montana study showed the following
average percent cover of bearberry 3 years after fire on plots burned at
different intensities [130]:

    Unburned       Light burn     Medium burn     Hot burn
      3.27            1.80            0.89          none

Following spring burning in a Montana shrubfield created 35 years
previously by wildfire, bearberry volume decreased the first two
seasons, but bearberry appeared to be recovering well [101].  Bearberry
had an average of 0.6 percent frequency in samples from sites where
slash pile fires occurred 2 to 15 years previously and was considered to
be a retreater on hotly burned sites [144].  Following fire in Colorado
lodgepole pine forest stands, bearberry was one of the major shrub
dominants during the first century of succession [17].  However, data
from this study do not show any bearberry in the first few years after
fire [17].  Ten or 11 years after fire on the Tillamook Burn in Oregon,
bearberry had 11 percent frequency on burned areas and was not present
in or near plots in adjacent unburned forest [98].  Following fire in
British Columbia, bearberry cover is weakly correlated with
environmental factors.  Evidently, bearberry is able to grow on a
variety of sites under postfire conditions [41].  Twenty-nine years
after an alpine wildfire in British Columbia, bearberry cover and
frequency were slightly higher in burned areas of both krummholz and
heath than in unburned areas [32].

During the first 3 years after prescribed fire on jack pine clearcuts in
Michigan, bearberry cover and frequency were very low when compared to
similar clearcuts that were not burned or undisturbed forest [1].
Another Michigan study found the highest postfire frequency of bearberry
occured 31 years after fire [120].  Results of a paired plot study in
the northern Wisconsin pine barrens indicated that bearberry frequency
decreases after a single fire or repeated fires [143].


FIRE MANAGEMENT CONSIDERATIONS : 
Equations have been developed for estimating the fuel loading of
bearberry from cover and plant height values in the northern and central
Rocky Mountains [4,16].

Related categories for Species: Arctostaphylos uva-ursi | Bearberry