FIRE EFFECTS
SPECIES: Sequoia sempervirens | Redwood 



IMMEDIATE FIRE EFFECT ON PLANT : 
The effect of fire on redwood varies depending on the size of the tree.
The bark of young trees (less than 8 inches [20 cm] d.b.h.) is generally
too thin to protect the cambium from damage, and trees of this size are
usually top-killed by cool to hot fires [16].  The thick bark of mature
redwood insulates the cambium from the heat of the fire [15], and in
many cases, fire may only reduce bark thickness [40].  Under more severe
circumstances, such as stand-replacing fires, basal wounding and
top-kill occurs [40].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
Young trees originating from stump sprouts have a higher rate of
top-kill after fire than those originating from seedlings (see fire case
study) [16].

Basal wounding provides a vector for heart rot to enter the tree.  Once
this has occurred, recurring fires and basal decay produce large basal
cavities, called goosepens, that weaken the tree [40].


PLANT RESPONSE TO FIRE : 
After fires that destroy all aboveground portions, both mature and young
redwoods will sprout from the root crown [40]; even seedlings have the
ability to sprout after top-kill [30].  After fires that destroy the
crown, redwoods greater than 8 inches (20 cm) will sprout from numerous
dormant buds along the bole and produce new foliage (see fire case
study) [14,16,40].

Redwood can also reestablish after fire via on-site and off-site seed
[43].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
After crown-kill redwood sprouts new foliage from dormant buds along the
bole.  The bole is covered with fine feathery foliage extending 2 to 3
feet (0.6-0.9 m) out from the bole.  This manifestation is called a
fire-column.  Over time the narrowed crown will again develop into a
typical crown.  During the first 4 postfire years the tree will produce
very few strobili [40].

After top-kill, the number of sprouts per root crown depends on the
severity of the fire.  Severe heat influx to the root crown kills more
of the dormant buds, thus reducing the number of sprouts; however, this
allocates more of the carbohydrate reserves to fewer sprouts, which
results in larger and taller sprouts [14].


FIRE MANAGEMENT CONSIDERATIONS : 
A fire regime where prescribed fire substitutes for lightning and
now-absent aboriginal ingitions may have to be implemented to maintain
or reestablish presettlement conditions in old-growth or cutover redwood
forests [15].  McBride and others [34] recommend that both frequency
distributions of fire intervals and an analysis of the pattern of fire
intervals be used as a basis for determining reburn intervals for
prescribed fire.  They evaluated the fire history of redwood forest
stands in Muir Woods National Monument and, because of the highly skewed
frequency distribution observed in this type, suggested that the average
fire interval would be inappropriate to use as a reburn interval.
Instead a combination of shorter than the average and longer than the
average natural fire interval was recommended.  In areas where fire has
been excluded for many decades, a prescribed fire program should start
with two short-interval fires (less than average interval) to reduce
high fuel accumulations.  Once the fuel load has been reduced, a burning
pattern of two short fire intervals followed by a long interval should
be implemented [34].

Person and Hallin [43] reported that regeneration was 5 to 10 times
greater on cuts with moderate to hot slash fires than on those with cool
or no slash fires.  Hallin [23] proposed the following guidelines for
slash fires:

       (1)  burn at night
       (2)  do not burn during the dry season (June thru September)
       (3)  light winds
       (4)  keep the area small (less than 40 acreas [16 ha])
       (5)  slash loads pulled away from advance regeneration

If sprouts are to be used as part of stand regeneration, the stumps
should not be debarked or severely burned during slash disposal, as
these actions will result in lowered sprout stocking [10].

Finney [14] has developed equations to estimate the fuel loading of the
forest floor in redwood stands based on forest floor depth.

Related categories for Species: Sequoia sempervirens | Redwood