FIRE EFFECTS
SPECIES: Cornus florida | Flowering Dogwood 



IMMEDIATE FIRE EFFECT ON PLANT : 
Flowering dogwood has been variously described as a fire-tolerant [53]
and fire-intolerant species [34].  Its bark is among the thinnest of all
eastern trees [40], and mature individuals are readily damaged by fire
[65].  Approximately 50 percent of all flowering dogwood stems were
top-killed by fire in south-central New York [89] and 58 percent
mortality was reported after a prescribed burn in a 22-year old loblolly
pine plantation in Tennessee [101].  All aboveground portions of the
plants died within 1 year of a fire in the Northeast [31].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
Hodgkins [43] observed that fire-caused mortality in small hardwoods is
related to diameter, season of burn, weather, frequency of fire, and the
amount of heat received at the ground line.  In relatively hot, dry
portions of eastern Texas, flowering dogwood was killed by winter,
spring, and fall burns repeated after 2 years [43].  Hot annual summer
fires may be necessary to kill small hardwoods in moist areas of the
Southeast.  Gill and Healy [31] reported that flowering dogwood can
survive infrequent low severity winter fires when plants are at least 10
to 15 feet (3-5 m) in height.

Fire-caused mortality of flowering dogwood is correlated with the amount
of heat received at the cambium.  The mean time required for the cambium
to reach lethal temperatures (approximately 140 degrees F [60 degrees
C]) has been reported as follows [39]:

      bark thickness                      seconds required for cambium
      (in inches)                               to reach 140 degrees F

      0.20                                      30.4
      0.30                                      59.4
      0.40                                     126.2


PLANT RESPONSE TO FIRE : 
Flowering dogwood usually sprouts profusely from the stump or root crown
after plants are top-killed or damaged by fire [31,65].  Specific
postfire response is related to fire severity and intensity, season of
burn, site factors, and fire frequency.  Postfire recovery is generally
more rapid after surface fires than after crown fires [70] [see
Qualification and Discussion of Plant Response to Fire].

In south-central New York, Swan [89] reported an average of 7.2 sprouts
per top-killed stem.  Postfire increases in sprout numbers have been
reported in oak-hickory stands of Missouri and in upland hardwood stands
of northern Alabama [45,59,65].  Prefire frequency of flowering dogwood
was measured at 1, with stem densities of 153 per acre (378/ha).  Ten
years after fire, frequency had climbed to 9, with stem densities of 267
per acre (660/ha) [59].  Increases in stem density were recorded after 2
burns in an oak-pine stand of Kentucky [98].  However, frequent fires at
short intervals can reduce the relative number of flowering dogwood
stems.  Comparisons of flowering dogwood on an annually burned plot and
on an adjacent plot left undisturbed for 15 years are as follows [23]:

         # stems/acre        rel. dom. %       rel. dens. %    freq. %

15 yr.        115               2                      73       5
annual burn     8               < 1                    13       7



DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
Cover:  The cover of flowering dogwood was estimated at 33.7 percent of
the total basal area on unburned plots in a loblolly pine community of
North Carolina [70].  After a surface fire, crown cover was reduced to
14.6 percent of the total basal area and accounted for only 10.2 percent
after a crown fire.  Specific results are as follows [70]:

                  density %         freq. %           basal area

unburned          13.1              100               4.47
surface fire       7.3               80               0.80
crown fire        10.6               90               0.70 

Fruit/seed production:  Landers [53] reported that fruit production may
be greater during the first year after fire.  Average fruit yields were
as follows after a winter prescribed burn in the Southeast [88]:

                1973            1975
                (preburn)       (1 yr. after burn)

burn            0.86            30.75
control         1.12             9.21

Cushwa and others [17] reported postfire decreases in seed production in
Georgia.


FIRE MANAGEMENT CONSIDERATIONS : 
NO-ENTRY

Related categories for Species: Cornus florida | Flowering Dogwood