FIRE ECOLOGY
SPECIES: Populus grandidentata | Bigtooth Aspen 



FIRE ECOLOGY OR ADAPTATIONS : 
Although bigtooth aspen is easily top-killed by fire, extensive
vegetative reproduction, prolific off-site seed production, and the
tenacity and lateral extent of its roots enable bigtooth aspen to
perpetuate after fire [44,56].  Removal of the overstory and heating of
the soil stimulate the sprouting of aspen roots [43,44,48].  Fire also
creates a suitable seedbed and reduces competition [56].

Aspen almost always retains or extends its range following fire [15].
The extensive aspen root system allows it to dominate the postfire
forest, even if aspen was only a minor component of the prefire stand
[13,44].  Aspen roots persist an undetermined length of time in the
absence of canopy aspen, making it possible for aspen to regenerate in a
stand in which aspen was not even represented in the prefire overstory
[44].

Aspen-dominated forests do not readily burn, especially when young and
healthy [15,27,44].  Slow burning, low-severity surface fires are
typical [15,25,27,48].  Decadent aspen stands contain more fuel and are
more likely to burn than younger stands [15,44].  An understory of
conifer species increases the flammability of aspen stands [24].
However, aspen is generally incapable of supporting a severe fire [25].
Crown fires in the surrounding forest generally drop into surface and
ground fuels when they enter aspen stands [15].

Fire every 150 years may be necessary to maintain aspen [56].
Presettlement fires in aspen stands probably occurred most often in the
fall when fuels are dry and leaf litter is deep [31].  The presettlement
fire interval of aspen-birch-fir forests in the Great Lakes Region is
estimated to have been about 80 years for very large [greater than
10,000 acre (4,000 ha)] fires [24].

Aspen-birch forests may have burned at intervals of 50 years or less
[23].  Fahey and Reiners [71] estimated that aspen-birch forests in
Maine had a 100-year fire interval during the 50-year period from 1909
to 1959.  However, this estimate may be high because fires were
declining during this time period due to fire suppression.

Heinselman [24] suggested that aspen parklands had fire intervals of 10
years for large [1,001 to 10,000 acre (400-4,000 ha)] fires.
Although quaking aspen is the principal tree in aspen parklands [24],
bigtooth aspen occurs in the prairie-forest edge in Minnesota [19].

Historically, bigtooth aspen frequently occurred in vegetational
patterns that are associated with fire.  For instance, bigtooth aspen
occurred with oak and quaking aspen along the west side of the Big Woods
in Minnesota.  These fire-tolerant species served as a firebreak between
the frequently burned prairie and the fire-sensitive climax forest of
the Big Woods.  Aspen served as a fire break because grassland fires
normally did not travel far into aspen stands due to low flammability.
However, fuel would build up in the aging aspen stands and eventually an
intense fire would destroy the aboveground biomass, rejuvenate the
aspen, and eliminate the less fire-tolerant species.  At the same time,
frequent fire in the prairie prevented aspen expansion [19].

Another example of a fire-influenced vegetational pattern is in the
Boundary Waters Canoe Area in Minnesota.  Aspen commonly occurs in areas
that frequently burn, such as large uplands areas distant from water and
upwind of natural fire breaks such as lakes [23].



POSTFIRE REGENERATION STRATEGY : 
   Tree with adventitious-bud root crown/soboliferous species root sucker
   Initial-offsite colonizer (off-site, initial community)

Related categories for Species: Populus grandidentata | Bigtooth Aspen