FIRE EFFECTS
SPECIES: Chrysolepis chrysophylla | Giant Chinquapin 



IMMEDIATE FIRE EFFECT ON PLANT : 
Giant chinquapin is a fire-sensitive species; aboveground portions are
extremely susceptible to fire mortality [2,10].  Thin bark provides
little insulation from radiant heat, which usually kills the cambium
around the base of the stem [48].  As a result, low-intensity ground
fires readily top-kill giant chinquapin seedlings and saplings [36].
Larger trees with thicker bark frequently survive light underburning on
favorable growth sites within redwood and mixed-evergreen forests
[40,63].  Although bole injuries usually result following initial
burning, fire scars tend to heal over rapidly in young, vigorous trees
[2,40].  Occasionally, large diameter trees survive repeated burning;
these trees commonly exhibit catface-scars and rotten cores [40].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
Limited information on the fire ecology of giant chinquapin on mixed
evergreen sites indicates that trees greater than 14 inches (35 cm)
d.b.h. are generally more tolerant of ground fires than similarly sized
hardwoods such as bigtooth maple (Acer macrophyllum) and tanoak [40].
On sites where the last major fire occurred 75 to 80 years prior to
observation, almost all giant chinquapins over 18 inches (45 cm) d.b.h.
exhibited fully or partially healed fire scars.  Only the largest
diameter trees, those ranging between 36 and 49 inches (91 and 122 cm)
d.b.h., showed evidence of repeated burning.  Fire-scarred giant
chinquapins occupying more mesic situations were usually single stemmed
[40].

Giant chinquapin appears more susceptible to fire mortality when it
occurs beneath a mature conifer overstory [46].  Plants suffering
competition are under increased stress and are less able to survive
fires than when they grow in a more open environment.  Although all
giant chinquapins resprouted following an initial, light-intensity
underburn on a mixed-conifer site in central Oregon, 50 percent died
after a reburn which consumed a high percentage of duff [46].  (See Fire
Case Study for more details.)


PLANT RESPONSE TO FIRE : 
Giant chinquapin initiates a rapid postburn recovery by sprouting from
adventitious buds located on a burl at the soil surface [22,54].  Since
burls are aggregations of buds, newly resprouted giant chinquapin
individuals occur as "sprout clumps" and are characterized by large
numbers of sprouts [38,48].  Sprouts are quite tolerant of direct
sunlight and develop well in the newly opened postburn environment
[18,49,58].  Fifty years following fire on a xeric mixed-evergreen site,
giant chinquapin individuals averaged two to three stems per clump with
an average d.b.h. of 11.2 inches (28 cm); largest stems of sprout origin
measured nearly 80 feet (24 m) tall and 18.4 inches (46 cm) d.b.h. [40].

Although abundance is initially reduced following burning, giant
chinquapin is a residual species which rapidly regains preburn levels if
fires are not too severe [13,26].  Preburn canopy coverage and density
are usually regained within 2 to 5 years on mixed-conifer sites in the
southern Oregon Cascades [36,65].  Recovery potential does not appear
significantly affected by early spring versus fall burning [65].
Sprouting vigor can, however, be greatly reduced when plants are
subjected to high duff consumption underburns [46]. (See Fire Case Study
for more information.)


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Western hemlock communities:  Giant chinquapin grows as a small tree or
aborescent shrub on undisturbed western hemlock sites in western Oregon
[36].  As a result, few stems survive fire to provide seed for postburn
seedling establishment.  Off-site seed may be transported by animals
[66].

Studies of early secondary succession on western hemlock sites in the
central western Cascades of Oregon indicate that giant chinquapin
exhibits only minor long-term changes in abundance following clearcut
logging and burning [12,13,26].  Whereas patterns of giant chinquapin
abundance varied between sampled watersheds, trends over a 20 year
period showed a gradual, continuous increase in cover once preburn
levels were regained (usually within 4 years).  Constancy remained
relatively stable or increased slightly.  Giant chinquapin was a
relatively minor component of the predisturbance vegetation on both
sites.

Trends in giant chinquapin cover at various intervals following
clearcutting, broadcast burning (medium intensity, fall burn), and
planting with Douglas-fir are presented below [57].  Sites support the
western hemlock/Pacific rhododendron/salal habitat type which is
associated with warm and moderately dry environments at low to mid
elevations in the western Cascades of Oregon.

                                      Mean cover (%)
    undisturbed old-growth              1.40
    interval since disturbance
     2 years                            0.09
     5 years                            0.05
    10 years                            0.22
    15 years                            2.52
    20 years                            0.63
    30 years                            0.56
    40 years                            3.85


FIRE MANAGEMENT CONSIDERATIONS : 
Broadcast burning:  Where conifer regeneration is a primary management
concern, broadcast burning is generally an ineffective site preparation
tool following clearcutting in conifer-hardwood stands.  Even though
burning delays the recovery of giant chinquapin for approximately one
growing season, removal of logging debris promotes sprouting by exposing
basal buds to solar heating and permits sprouts to grow unimpeded [47].
Following logging and burning of mixed-evergreen sites in the Siskiyou
Mountains and the southern Cascades, giant chinquapin is often a
component of seral brushfields.  Sites especially prone to the rapid
development of a dense giant chinquapin cover are drier sites within
mixed-conifer communities where predisturbance giant chinquapin
densities are relatively high.  Densities are likely to be increased on
dry, nutrient-poor soils where giant chinquapin seedlings become
increasingly competitive [47].

On mixed-conifer sites where depauperate plants are able to persist
beneath dense conifer overstories, giant chinquapin is frequently an
inconspicuous component of the preburn vegetation.  Large initial
increases in postburn cover can be expected from residual plants
[36,64].

Preharvest burning:  Giant chinquapin sprouting may be more effectively
controlled by preharvest underburning [46].  Although all top-killed
plants sprouted following an intial underburn, 50 percent of these
plants were killed by a second burn, and the sprouting vigor of
surviving plants was severely reduced [46].

Related categories for Species: Chrysolepis chrysophylla | Giant Chinquapin