FIRE EFFECTS
SPECIES: Quercus agrifolia | Coast Live Oak 



IMMEDIATE FIRE EFFECT ON PLANT : 
Coast live oak seedlings and saplings less than 2 inches (5 cm) in
d.b.h. are top-killed by moderate-severity fire, and severe fire may
kill trees of this size [24,66].  Saplings between 2 to 6 inches (5-15
cm) in d.b.h. are top-killed by severe fire.  Larger trees are usually
not top-killed by severe fire.  The Soboba Fire on the San Bernadino
National Forest, classified as an extremely hot crown fire, killed only
4 percent of burned coast live oak.  Ninety percent of the oaks less
than 3 inches (7.6 cm) in d.b.h. were top-killed, and 2 percent were
killed.  Of trees greater than 6 inches (15.2 cm) in d.b.h., the trunks
and crowns of all but 5 percent survived the fire.  Of this 5 percent, 3
percent were top-killed, and 2 percent suffered complete kill [66].

Roots are protected by an outer corky layer and the soil itself.  Coast
live oak roots generally suffer little direct heat damage except feeder
roots near the soil surface [66].

Acorns on the soil surface are killed by low-severity fire, while
animal-buried acorns usually survive moderate-severity fire.  Severe
fire, however, may kill even buried acorns.  Following a severe fire in
Ventura County, burned sites supported no coast live oak germinants
supported no germinants the following spring, while adjacent unburned
areas produced new seedlings [21].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
Mortality  of coast live oak is greater when there is a considerable
shrub understory or when trees are adjacent to chaparral.  Coast live
oak in the Santa Monica Mountains were killed in large numbers when a
hot chaparral fire burned into the oak woodland [78].


PLANT RESPONSE TO FIRE : 
Coast live oak generally recovers well from fire, although severely
burned crowns, trunks, and root crowns may require several years to
sprout.  Oaks are more likely to be damaged by fall fire than earlier
fires.  The most common fire damage to the trunk is a basal wound
resulting in cambium death.  Small wounds less than a few inches may
eventually heal with no accompanying heart rot, but larger wounds are
subject to fungal disease and insect attack [76].  Winter fire causes
the least damage [67].  Recovery of trees on the Soboba Burn was as
follows [66]:

                                           Tree condition, May 1979
                                              
                   Number of               Basal     Basal and     Crown   
Tree diameter    charred trees,   Dead    sprouts      crown      sprouts 
(d.b.h., in.)      Aug. 1974               only       sprouts      only
                                  ________________Percent________________
    0- 3              90            2       88           1           9
    3- 6              54           11       26          28          35
    6-12              65            1        5          52          42
   12-18              24            0        0          62          38
   18+                22            4        5          50          41 

Crown density typically reaches 80 percent of preburn level in 10 years
on favorable sites [39].

Low-severity fire apparently favors regeneration.  Coast live oak
populations were increased from preburn levels following a low-severity
fire in Cuyamaca State Park [45,48].


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 



FIRE MANAGEMENT CONSIDERATIONS : 
Use of fire is recommended for managing coast live oak [66].  The
outstanding fire resistance of this species ensures that few large trees
will be killed by moderate-severity prescribed fire.  Natural
regeneration has improved following prescribed burning [48].  Fire will
eliminate competing conifers from areas where they are invading oak
woodland [39].  Regeneration is also favored because scrub jays prefer
burns as acorn-caching sites [59].

Large trees do not always sprout at the first postfire growing season,
and Plumb and Gomez [67] recommend waiting at least one growing season,
possibly up to three, before cutting large trees with uncertain
potential for crown survival.  The following guide suggests when to
harvest coast live oak, based upon tree size and degree of trunk char*
[66]:

Less than 6 in. d.b.h.         6-12 in. d.b.h.       More than 12 in. d.b.h.
______________________     ______________________    _______________________
Light   Medium   Heavy     Light   Medium   Heavy    Light   Medium   Heavy
char     char    char      char     char    char     char     char    char
 Lv       Lv      Cut       Lv       Lv      Lv       Lv       Lv      Lv
____________________________________________________________________________
*Assumes that 100% of trunk circumference is affected, as follows:
Light=spotty char or scorch, scattered pitting; Medium=continuous
charring, areas of minor reduction in bark thickness; Heavy=continuous
charring and pronounced reduction in bark thickness with wood sometimes
exposed.  Lv means the tree should be left uncut for 3 yrs; Cut means
the tree can be cut immediately. 

Fire managers in southern California have made fire control lines in
coast live oak woodland when planning broadcast burning of adjacent
chaparral.  Potential control line sites are selected from nearby
riparian woodland areas, where the understory is burned in order to
make a fuelbreak [24].

Related categories for Species: Quercus agrifolia | Coast Live Oak